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2023, 44(1):219-227.
DOI: 10.19663/j.issn2095-9869.20211013001
Abstract:
At present, local and foreign research reports on Thunnus thynnus have focused on fishery biology, fishing, and genetic diversity, among others. There are few reports on nutrition and flavor related to the different muscles of T. thynnus. To scientifically evaluate the nutritional quality and major flavor of different muscle parts of T. thynnus, the basic nutritional components, amino acid composition, fatty acid composition, and volatile flavor substances of dorsal and abdominal muscles were compared. Except for ash, the moisture, crude protein, and fat contents varied significantly between the dorsal and abdominal muscles (P<0.05). The moisture contents of the dorsal and abdominal muscles were 57.79 g/100 g and 50.16 g/100 g, respectively. The protein content was 24.70 g/100 g and 18.61 g/100 g, respectively. The protein content of dorsal muscles was 24.70 g/100 g, which was 1.33 times that of the abdomen. The crude fat content of the dorsal muscles was 19.34 g/100 g, and in the abdomen was 30.29 g/100 g, which was 1.57 times that in the dorsal muscles. The crude ash content of dorsal and abdominal muscles was 1.01 g/100 g and 1.08 g/100 g, respectively. Seventeen amino acids were detected in different parts of T. thynnus. The total amino acid content differed significantly between the dorsal (22.07±0.74) g/100 gand abdominal muscles (16.57±0.47) g/100 g. The essential amino acid content of dorsal and abdominal muscles was (8.61±0.29) g/100 g and (6.28±0.17) g/100 g, respectively. The content of glutamate was the highest among the amino acids, followed by aspartic acid, and the content of cystine was the lowest. The ratio of essential amino acids to total amino acids of different muscle parts of T. thynnus was 40%, and the ratio of essential amino acids to nonessential amino acids was >60%, which was close to the ideal protein nutrition evaluation model recommended by the Food and Agriculture Organization of the United Nations/World Health Organization (FAO/WHO). Thus, the dorsal and abdominal muscles are high-quality proteins. The umami taste of aquatic products is closely related to the content of umami amino acids. Four types of umami amino acids showed the highest content levels, namely glutamic acid, aspartic acid, alanine, and glycine (in descending order of content level). The proportion of umami amino acids in dorsal and abdominal muscles was 34.93% and 35.91%, respectively, both exceeding 30%, which indicated that the dorsal and abdominal muscles of T. thynnus have a delicious quality. In the dorsal and abdominal muscles, 24 and 29 kinds of fatty acids were detected, including 8 and 12 kinds of saturated fatty acids, 6 kinds of monounsaturated fatty acids, and 10 and 11 kinds of polyunsaturated fatty acids, respectively, and there was a significant difference among the contents of different types of fatty acids. The contents of myristic acid, palmitic acid, and stearic acid were higher than those of other saturated fatty acids. The contents of oleic acid and eicosanoic acid were higher in monounsaturated fatty acids. The total content of eicosapentaenoic acid and docosahexaenoic acid in the dorsal and abdominal muscles accounted for 88.55% and 75.13% of polyunsaturated fatty acids, respectively. Therefore, the dorsal and abdominal muscles have good functional properties. The FAO/WHO recommends that the intake ratio of n-6 to n-3 polyunsaturated fatty acids in the diet should be 4:6, and the ratio of dorsal and abdominal muscles ranged from 0.41 to 0.44, which is much smaller than the standard. These results indicate that T. thynnus is rich in n-3 polyunsaturated fatty acids. A total of 39 volatile substances were detected in the dorsal and abdominal muscles of T. thynnus, including aldehydes, ketones, alcohols, esters, acids, alkenes, and compounds containing nitrogen and sulfur. PCA analysis showed that there was a significant difference between the odors of the dorsal and abdominal muscles of T. thynnus. Gas chromatography–ion mobility spectrometry can effectively be used to distinguish the different volatiles associated with the muscles. The relative contents of 2-methylthiophene, (E)-2-hexen-1-ol, pentanoic acid, alpha-pinene, propanoic acid, butyl butanoate, 2-pentylfuran, pentyl butanoate, dipropyl disulfide, diallyl disulfide, ethylheptanoate, alpha-terpineol, methylisobutylketone, 2-methylbutanal-D, and 2-methylbutanal-M were higher in the abdomen; the relative contents of (E)-2-pentenal, N-nitromethylethylamine, methylpyrazine, 3-methylbutanol, 1-2-dimethylbenzene, triethylamine, E-3-hexene-1-ol, 4-methyl-2-pentanol, ethyl 2-methylpropanoate, 2-butanone, ethyl acetate, 3-butenonitrile, and 2,4,5-trimethylthiazole were higher in abdominal muscle. The difference in composition and content caused the dorsal and abdominal muscles to form their own flavor characteristics, which were mainly related to the amino acid and fatty acid composition of the two parts. In general, the dorsal muscles mainly presented a fatty fragrance, whereas the abdominal muscles mainly presented a clear fragrance. The dorsal and abdominal muscles of T. thynnus are rich in nutrients and n-3 polyunsaturated fatty acids. Both muscles have a delicious taste, though they vary in flavor characteristics. This study provides a scientific basis for the deep processing and utilization of T. thynnus.
At present, local and foreign research reports on Thunnus thynnus have focused on fishery biology, fishing, and genetic diversity, among others. There are few reports on nutrition and flavor related to the different muscles of T. thynnus. To scientifically evaluate the nutritional quality and major flavor of different muscle parts of T. thynnus, the basic nutritional components, amino acid composition, fatty acid composition, and volatile flavor substances of dorsal and abdominal muscles were compared. Except for ash, the moisture, crude protein, and fat contents varied significantly between the dorsal and abdominal muscles (P<0.05). The moisture contents of the dorsal and abdominal muscles were 57.79 g/100 g and 50.16 g/100 g, respectively. The protein content was 24.70 g/100 g and 18.61 g/100 g, respectively. The protein content of dorsal muscles was 24.70 g/100 g, which was 1.33 times that of the abdomen. The crude fat content of the dorsal muscles was 19.34 g/100 g, and in the abdomen was 30.29 g/100 g, which was 1.57 times that in the dorsal muscles. The crude ash content of dorsal and abdominal muscles was 1.01 g/100 g and 1.08 g/100 g, respectively. Seventeen amino acids were detected in different parts of T. thynnus. The total amino acid content differed significantly between the dorsal (22.07±0.74) g/100 gand abdominal muscles (16.57±0.47) g/100 g. The essential amino acid content of dorsal and abdominal muscles was (8.61±0.29) g/100 g and (6.28±0.17) g/100 g, respectively. The content of glutamate was the highest among the amino acids, followed by aspartic acid, and the content of cystine was the lowest. The ratio of essential amino acids to total amino acids of different muscle parts of T. thynnus was 40%, and the ratio of essential amino acids to nonessential amino acids was >60%, which was close to the ideal protein nutrition evaluation model recommended by the Food and Agriculture Organization of the United Nations/World Health Organization (FAO/WHO). Thus, the dorsal and abdominal muscles are high-quality proteins. The umami taste of aquatic products is closely related to the content of umami amino acids. Four types of umami amino acids showed the highest content levels, namely glutamic acid, aspartic acid, alanine, and glycine (in descending order of content level). The proportion of umami amino acids in dorsal and abdominal muscles was 34.93% and 35.91%, respectively, both exceeding 30%, which indicated that the dorsal and abdominal muscles of T. thynnus have a delicious quality. In the dorsal and abdominal muscles, 24 and 29 kinds of fatty acids were detected, including 8 and 12 kinds of saturated fatty acids, 6 kinds of monounsaturated fatty acids, and 10 and 11 kinds of polyunsaturated fatty acids, respectively, and there was a significant difference among the contents of different types of fatty acids. The contents of myristic acid, palmitic acid, and stearic acid were higher than those of other saturated fatty acids. The contents of oleic acid and eicosanoic acid were higher in monounsaturated fatty acids. The total content of eicosapentaenoic acid and docosahexaenoic acid in the dorsal and abdominal muscles accounted for 88.55% and 75.13% of polyunsaturated fatty acids, respectively. Therefore, the dorsal and abdominal muscles have good functional properties. The FAO/WHO recommends that the intake ratio of n-6 to n-3 polyunsaturated fatty acids in the diet should be 4:6, and the ratio of dorsal and abdominal muscles ranged from 0.41 to 0.44, which is much smaller than the standard. These results indicate that T. thynnus is rich in n-3 polyunsaturated fatty acids. A total of 39 volatile substances were detected in the dorsal and abdominal muscles of T. thynnus, including aldehydes, ketones, alcohols, esters, acids, alkenes, and compounds containing nitrogen and sulfur. PCA analysis showed that there was a significant difference between the odors of the dorsal and abdominal muscles of T. thynnus. Gas chromatography–ion mobility spectrometry can effectively be used to distinguish the different volatiles associated with the muscles. The relative contents of 2-methylthiophene, (E)-2-hexen-1-ol, pentanoic acid, alpha-pinene, propanoic acid, butyl butanoate, 2-pentylfuran, pentyl butanoate, dipropyl disulfide, diallyl disulfide, ethylheptanoate, alpha-terpineol, methylisobutylketone, 2-methylbutanal-D, and 2-methylbutanal-M were higher in the abdomen; the relative contents of (E)-2-pentenal, N-nitromethylethylamine, methylpyrazine, 3-methylbutanol, 1-2-dimethylbenzene, triethylamine, E-3-hexene-1-ol, 4-methyl-2-pentanol, ethyl 2-methylpropanoate, 2-butanone, ethyl acetate, 3-butenonitrile, and 2,4,5-trimethylthiazole were higher in abdominal muscle. The difference in composition and content caused the dorsal and abdominal muscles to form their own flavor characteristics, which were mainly related to the amino acid and fatty acid composition of the two parts. In general, the dorsal muscles mainly presented a fatty fragrance, whereas the abdominal muscles mainly presented a clear fragrance. The dorsal and abdominal muscles of T. thynnus are rich in nutrients and n-3 polyunsaturated fatty acids. Both muscles have a delicious taste, though they vary in flavor characteristics. This study provides a scientific basis for the deep processing and utilization of T. thynnus.
2024, 45(3):268-277.
DOI: 10.19663/j.issn2095-9869.20230303001
Abstract:
Flavor is an important characteristic of seafood products, and drying can produce unique pleasant flavors. Drying is among the most common methods for processing seafood products. It can improve quality and shelf-life of seafood products and produce unique flavors. Oxidative hydrolysis of lipids during dry fish processing in the presence of light, photosensitizers, heat, oxygen, transition metal ions, and microorganisms produces volatile small molecules, including alcohols, ketones, aldehydes, and acids, which contribute to the flavor profile of dried fish. Volatile compounds are important components of seafood flavor. Flavor analyses are usually performed using gas chromatography-ion mobility spectrometry (GC-IMS) and gas chromatography-mass spectrometry (GC-MS) in combination with electronic nose/tongue techniques, which not only characterizes the molecular composition of volatile components in the sample, but also yields macroscopic results via the electronic nose/tongue, ultimately combining instrumental analysis with quantitative sensory data for a comprehensive evaluation of sample flavor. Currently, the market sales model of Cololabis saira is mainly based on a single frozen whole C. saira, and excludes most types of deep-processed products. There is an urgent need to enrich research into processing effects on C. saira quality and flavor, and further develop markets for deep-processed C. saira products. To explore the effects of different drying methods on C. saira flavor, we assessed flavor molecule profiles using GC-MS and electronic tongue techniques. This study aimed to provide a theoretical basis for improving C. saira product flavor, thereby enhancing the economic impact of the C. saira industry. In this study, C. saira was thawed in low-temperature air, and the giblets were removed and diagonally cut. Pre-treated fish were then soaked in 15% salt water for 1 h, drained naturally, and subjected to natural drying (natural air-drying on a sunny day in autumn for 3 days, environmental temperature 10~20 ℃, humidity 25%~42%), cold air-drying (continuous cold air-drying for 3 days, setting temperature (15±2) ℃, relative humidity 38%~40%), and UV with cold air-drying (continuous UV with cold air-drying for 3 days, ultraviolet lamp irradiation, setting temperature (15±2) ℃, relative humidity 38%~40%). The flavor profiles of fresh fish (CK), cured fish (0 d), naturally dried fish (N), cold air-dried fish (C), and UV treated cold air-dried fish (U) were compared. Significant differences were observed in the odor and taste of dried C. saira among products of the different drying methods. GC-MS results showed that a total of 58 volatile flavor substances were detected, including aldehydes, alcohols, ketones, acids, hydrocarbons, and nitrogenous compounds. Increased alcohols, aldehydes, and ketones enriched the fatty aroma of the three dried C. saira samples to varying degrees. Among them, the contents of cis-2-heptenal, octylaldehyde, 2-ethylfuran and other substances in U group increased significantly, increasing to 64.96, 569.48 and 189.27 μg/kg, respectively, so that the U group had richer fat flavor. Hexanal, heptanal, Z-4-heptenal, octanal, nonanal, (E,E)-2,4-heptadienal, (E,E)-2,6-nonandialdehyde, 1-octen-3-ol, heptanol, 2,3-pentanedione, 3,5-octadien-2-one, and trimethylamine were the odor-active substances common to the five C. saira samples and were used as flavor compounds to characterize the oily and fishy taste of C. saira. E-2-nonenal, 2-ethylfuran, E-2-octenal, 2-nonanone, 2-undecanone, and 1-nonanol are three odor-active substances specific to dried C. saira, with E-2-octenal, 1-nonanol and 2-undecanone, which have an oily smell, and 2-ethylfuran, which has a burnt smell, having the highest odor aroma-active in the U group. Salty taste, richness, bitterness, astringency, and sourness of the fish increased after the drying process, especially salty taste and richness. Only fresh taste was significantly reduced relative to fresh fish. Saltiness, freshness, and richness of dried fish are important taste indicators. Salty taste and richness increased significantly after the three drying processes, whereas freshness decreased. Group U exhibited the highest salty taste and richness. In conclusion, the volatile odor and profile of C. saira changed significantly with each of three drying processes (natural drying, cold air drying, and UV with cold air drying), all of which increased the fatty flavor and considerably reduced the fishy flavor. Moderate oxidation positively contributes to C. saira flavor. Increased fatty flavor reduces the proportion of fishy substances, thus improving C. saira flavor. UV irradiation with cold air drying promoted lipid oxidation to some extent, producing more fatty substances, as well as cis-2-heptenal and 2-ethylfuran, which enriched the roasted, charred flavor of dried C. saira. Salinity, freshness, and richness are important taste indicators of dried C. saira. All three drying methods enhanced the salinity and richness of C. saira, and UV irradiation with cold air-drying significantly improved the salinity and richness of the fish and enriched its taste and aftertaste. Therefore, among the three drying methods, the method involving UV with cold air drying significantly enriched the flavor of C. saira to the greatest extent.
Flavor is an important characteristic of seafood products, and drying can produce unique pleasant flavors. Drying is among the most common methods for processing seafood products. It can improve quality and shelf-life of seafood products and produce unique flavors. Oxidative hydrolysis of lipids during dry fish processing in the presence of light, photosensitizers, heat, oxygen, transition metal ions, and microorganisms produces volatile small molecules, including alcohols, ketones, aldehydes, and acids, which contribute to the flavor profile of dried fish. Volatile compounds are important components of seafood flavor. Flavor analyses are usually performed using gas chromatography-ion mobility spectrometry (GC-IMS) and gas chromatography-mass spectrometry (GC-MS) in combination with electronic nose/tongue techniques, which not only characterizes the molecular composition of volatile components in the sample, but also yields macroscopic results via the electronic nose/tongue, ultimately combining instrumental analysis with quantitative sensory data for a comprehensive evaluation of sample flavor. Currently, the market sales model of Cololabis saira is mainly based on a single frozen whole C. saira, and excludes most types of deep-processed products. There is an urgent need to enrich research into processing effects on C. saira quality and flavor, and further develop markets for deep-processed C. saira products. To explore the effects of different drying methods on C. saira flavor, we assessed flavor molecule profiles using GC-MS and electronic tongue techniques. This study aimed to provide a theoretical basis for improving C. saira product flavor, thereby enhancing the economic impact of the C. saira industry. In this study, C. saira was thawed in low-temperature air, and the giblets were removed and diagonally cut. Pre-treated fish were then soaked in 15% salt water for 1 h, drained naturally, and subjected to natural drying (natural air-drying on a sunny day in autumn for 3 days, environmental temperature 10~20 ℃, humidity 25%~42%), cold air-drying (continuous cold air-drying for 3 days, setting temperature (15±2) ℃, relative humidity 38%~40%), and UV with cold air-drying (continuous UV with cold air-drying for 3 days, ultraviolet lamp irradiation, setting temperature (15±2) ℃, relative humidity 38%~40%). The flavor profiles of fresh fish (CK), cured fish (0 d), naturally dried fish (N), cold air-dried fish (C), and UV treated cold air-dried fish (U) were compared. Significant differences were observed in the odor and taste of dried C. saira among products of the different drying methods. GC-MS results showed that a total of 58 volatile flavor substances were detected, including aldehydes, alcohols, ketones, acids, hydrocarbons, and nitrogenous compounds. Increased alcohols, aldehydes, and ketones enriched the fatty aroma of the three dried C. saira samples to varying degrees. Among them, the contents of cis-2-heptenal, octylaldehyde, 2-ethylfuran and other substances in U group increased significantly, increasing to 64.96, 569.48 and 189.27 μg/kg, respectively, so that the U group had richer fat flavor. Hexanal, heptanal, Z-4-heptenal, octanal, nonanal, (E,E)-2,4-heptadienal, (E,E)-2,6-nonandialdehyde, 1-octen-3-ol, heptanol, 2,3-pentanedione, 3,5-octadien-2-one, and trimethylamine were the odor-active substances common to the five C. saira samples and were used as flavor compounds to characterize the oily and fishy taste of C. saira. E-2-nonenal, 2-ethylfuran, E-2-octenal, 2-nonanone, 2-undecanone, and 1-nonanol are three odor-active substances specific to dried C. saira, with E-2-octenal, 1-nonanol and 2-undecanone, which have an oily smell, and 2-ethylfuran, which has a burnt smell, having the highest odor aroma-active in the U group. Salty taste, richness, bitterness, astringency, and sourness of the fish increased after the drying process, especially salty taste and richness. Only fresh taste was significantly reduced relative to fresh fish. Saltiness, freshness, and richness of dried fish are important taste indicators. Salty taste and richness increased significantly after the three drying processes, whereas freshness decreased. Group U exhibited the highest salty taste and richness. In conclusion, the volatile odor and profile of C. saira changed significantly with each of three drying processes (natural drying, cold air drying, and UV with cold air drying), all of which increased the fatty flavor and considerably reduced the fishy flavor. Moderate oxidation positively contributes to C. saira flavor. Increased fatty flavor reduces the proportion of fishy substances, thus improving C. saira flavor. UV irradiation with cold air drying promoted lipid oxidation to some extent, producing more fatty substances, as well as cis-2-heptenal and 2-ethylfuran, which enriched the roasted, charred flavor of dried C. saira. Salinity, freshness, and richness are important taste indicators of dried C. saira. All three drying methods enhanced the salinity and richness of C. saira, and UV irradiation with cold air-drying significantly improved the salinity and richness of the fish and enriched its taste and aftertaste. Therefore, among the three drying methods, the method involving UV with cold air drying significantly enriched the flavor of C. saira to the greatest extent.
CHEN Shengjun
,
GAO Fangfang
,
WANG Di
,
FENG Yang
,
DENG Jianchao
,
PAN Chuang
,
ZHAO Yongqiang
,
LI Chunsheng
2023, 44(4):244-253.
DOI: 10.19663/j.issn2095-9869.20220321002
Abstract:
Nitrofurazone is a synthetic antimicrobial drug developed by the Eaton Institute in the United States in the 1950s. Nitrofurazone can play an inhibitory or bactericidal role by interfering with the glucose metabolism process and oxidase system in bacteria. Due to its strong bactericidal ability, wide antibacterial spectrum, and low price, it was widely used in animal husbandry and aquaculture. Nitrofurazone is detected in animals because it is rapidly metabolized, with a half-life of only a few hours. Semicarbazide (a typical metabolite of nitrofurazone) is detected in food-borne products in a linear proportion to the amount of nitrofurazone added to the animal. Semicarbazide binds to animal proteins to generate stable residues and is difficult to metabolize completely. The United States, European Union, China, and other countries detect and monitor semicarbazide as a marker of nitrofurazone drugs. Nitrofurazone (and its metabolite semicarbazide) have teratogenic and carcinogenic effects on the human body. Any residues in animal-derived foods can be transmitted to humans through the food chain. Long-term intake of semicarbazide in humans will cause anemia, liver necrosis, neuritis, and damages the eyeball and DNA. Therefore, the United States, the European Union, and other countries have explicitly banned its use in the food industry. China has listed nitrofurazone as a banned drug and specified that nitrofurazone and its metabolites should not be detected in animal-derived foods. Over the years, the detection of semicarbazide has been limited by the detection methods and instruments. The Ministry of Agriculture has stated the residual limit of semicarbazide as 1.0 μg/kg and assigned a supervision and sampling inspection program. Existing studies have identified the semicarbazide detected in crustacean aquatic products combines the residue caused by nitrofurazone metabolism and other obvious sources of semicarbazide, which include: 1) the presence of endogenous sources in crustacean aquatic animals; 2) the growth environment and feed intake; and 3) aquatic product processing. Previously, semicarbazide residues were generally considered to be the result of excessive nitrofurazone drug use by farmers. In recent years, the farmers state they have not used nitrofurazone during aquaculture. However, semicarbazide has been present in seafood. In 2004, Saari et al. detected semicarbazide in Procambarus clarkii that did not consume nitrofurazone and provided the first report that crustaceans may naturally produce semicarbazide, which is causing the detection of semicarbazide in many cultured crustacean aquatic animals that have not been fed nitrofurazone drugs (represented by shrimp and crab). This research confirms the presence of endogenous semicarbazones in crustacean aquatic products. In addition, the natural living environment of crustacean aquatic animals is polluted with semicarbazide due to economic human activities. Many scientists have detected the presence of semicarbazide in the waters and sediments in various regions. Concurrently, semicarbazides also contaminate aquatic plants. Semicarbazide is a new water pollutant that exists in water bodies and plants, which is continuously enriched and enters organisms. Nitrofurazone is a commonly used antibiotic for aquaculture products and is often detected when the amino residues exceed the standard levels due to illegal addition by farmers. Studies have shown that semicarbazide is also introduced through processing aquatic products, such as sodium hypochlorite disinfection resulting in an increase in the levels of semicarbazide, by azodicarboxamide through thermal decomposition producing semicarbazide and so on. The biological toxicity of semicarbazide and the food chain transfer effect have ensured semicarbazide is now an important environmental and food pollutant. In the current aquatic trade in China, the presence of endogenous semicarbazide in crustacean aquatic products has serious impacts and interferes in the detection of nitrofurazone drugs, resulting in an inability to accurately determine semicarbazide sources. It is of great importance to thoroughly analyze and understand the main sources and formation mechanism of SEM in crustacean aquatic products to ensure the healthy development of the aquaculture industry in China. At present, there are two statements on the formation mechanism of endogenous semicarbazide: arginine is involved in the urea cycle of crustacean aquatic animals and semicarbazide is produced through the oxadine intermediate. An analysis of content changes in the main substances of the urea cycle revealed the formation of endogenous semicarbazide is closely related to the guanidinyl and amide groups of arginine, citrulline, and the amide structure of urea. Arginine is a potentially important factor in the formation of endogenous semicarbazide; secondly, SEM is derived from a single cell epidermis that produces chitin. There is a single cell epidermal layer secreting chitin between the shrimp shell and shrimp meat, and the detection level of semicarbazide in the shrimp meat close to this epidermal layer was more than three times higher than the inner shrimp meat. Therefore, the semicarbazide in shrimp meat mainly originates from the epidermal layer cells producing chitin. Two inferences on the formation mechanism of exogenous semicarbazide are: the carbamate ions in hypochlorite solution may react with ammonia or acid amide in aquatic products to generate hydrazine, and hydrazine reacts with urea and other compounds through the urea cycle to generate semicarbazide, increasing the production of semicarbazide; the azodicarbonamide added in processing is degraded to biurea at high temperatures, and biurea is then converted to semicarbazide by the hydrolysis reaction. Considering the different molecular structures between nitrofurazone and biurea, the speculation that nitrofurazone is metabolized to produce biurea can be ruled out. From existing studies, azodicarbonamide is the only biological source of biurea, so biurea can be used as the corresponding target detector of azodicarbonamide. To solve the problem that endogenous and exogenous semicarbazide cannot be distinguished in aquatic products in China, the endogenous and exogenous pathways of semicarbazide and the corresponding possible formation mechanisms are reviewed in this paper. The formation pathways of endogenous semicarbazide are speculated to help solve the formation mechanism of semicarbazide in crustacean aquatic products and provide scientific data for the standardization of semicarbazide residue limits in China.
Nitrofurazone is a synthetic antimicrobial drug developed by the Eaton Institute in the United States in the 1950s. Nitrofurazone can play an inhibitory or bactericidal role by interfering with the glucose metabolism process and oxidase system in bacteria. Due to its strong bactericidal ability, wide antibacterial spectrum, and low price, it was widely used in animal husbandry and aquaculture. Nitrofurazone is detected in animals because it is rapidly metabolized, with a half-life of only a few hours. Semicarbazide (a typical metabolite of nitrofurazone) is detected in food-borne products in a linear proportion to the amount of nitrofurazone added to the animal. Semicarbazide binds to animal proteins to generate stable residues and is difficult to metabolize completely. The United States, European Union, China, and other countries detect and monitor semicarbazide as a marker of nitrofurazone drugs. Nitrofurazone (and its metabolite semicarbazide) have teratogenic and carcinogenic effects on the human body. Any residues in animal-derived foods can be transmitted to humans through the food chain. Long-term intake of semicarbazide in humans will cause anemia, liver necrosis, neuritis, and damages the eyeball and DNA. Therefore, the United States, the European Union, and other countries have explicitly banned its use in the food industry. China has listed nitrofurazone as a banned drug and specified that nitrofurazone and its metabolites should not be detected in animal-derived foods. Over the years, the detection of semicarbazide has been limited by the detection methods and instruments. The Ministry of Agriculture has stated the residual limit of semicarbazide as 1.0 μg/kg and assigned a supervision and sampling inspection program. Existing studies have identified the semicarbazide detected in crustacean aquatic products combines the residue caused by nitrofurazone metabolism and other obvious sources of semicarbazide, which include: 1) the presence of endogenous sources in crustacean aquatic animals; 2) the growth environment and feed intake; and 3) aquatic product processing. Previously, semicarbazide residues were generally considered to be the result of excessive nitrofurazone drug use by farmers. In recent years, the farmers state they have not used nitrofurazone during aquaculture. However, semicarbazide has been present in seafood. In 2004, Saari et al. detected semicarbazide in Procambarus clarkii that did not consume nitrofurazone and provided the first report that crustaceans may naturally produce semicarbazide, which is causing the detection of semicarbazide in many cultured crustacean aquatic animals that have not been fed nitrofurazone drugs (represented by shrimp and crab). This research confirms the presence of endogenous semicarbazones in crustacean aquatic products. In addition, the natural living environment of crustacean aquatic animals is polluted with semicarbazide due to economic human activities. Many scientists have detected the presence of semicarbazide in the waters and sediments in various regions. Concurrently, semicarbazides also contaminate aquatic plants. Semicarbazide is a new water pollutant that exists in water bodies and plants, which is continuously enriched and enters organisms. Nitrofurazone is a commonly used antibiotic for aquaculture products and is often detected when the amino residues exceed the standard levels due to illegal addition by farmers. Studies have shown that semicarbazide is also introduced through processing aquatic products, such as sodium hypochlorite disinfection resulting in an increase in the levels of semicarbazide, by azodicarboxamide through thermal decomposition producing semicarbazide and so on. The biological toxicity of semicarbazide and the food chain transfer effect have ensured semicarbazide is now an important environmental and food pollutant. In the current aquatic trade in China, the presence of endogenous semicarbazide in crustacean aquatic products has serious impacts and interferes in the detection of nitrofurazone drugs, resulting in an inability to accurately determine semicarbazide sources. It is of great importance to thoroughly analyze and understand the main sources and formation mechanism of SEM in crustacean aquatic products to ensure the healthy development of the aquaculture industry in China. At present, there are two statements on the formation mechanism of endogenous semicarbazide: arginine is involved in the urea cycle of crustacean aquatic animals and semicarbazide is produced through the oxadine intermediate. An analysis of content changes in the main substances of the urea cycle revealed the formation of endogenous semicarbazide is closely related to the guanidinyl and amide groups of arginine, citrulline, and the amide structure of urea. Arginine is a potentially important factor in the formation of endogenous semicarbazide; secondly, SEM is derived from a single cell epidermis that produces chitin. There is a single cell epidermal layer secreting chitin between the shrimp shell and shrimp meat, and the detection level of semicarbazide in the shrimp meat close to this epidermal layer was more than three times higher than the inner shrimp meat. Therefore, the semicarbazide in shrimp meat mainly originates from the epidermal layer cells producing chitin. Two inferences on the formation mechanism of exogenous semicarbazide are: the carbamate ions in hypochlorite solution may react with ammonia or acid amide in aquatic products to generate hydrazine, and hydrazine reacts with urea and other compounds through the urea cycle to generate semicarbazide, increasing the production of semicarbazide; the azodicarbonamide added in processing is degraded to biurea at high temperatures, and biurea is then converted to semicarbazide by the hydrolysis reaction. Considering the different molecular structures between nitrofurazone and biurea, the speculation that nitrofurazone is metabolized to produce biurea can be ruled out. From existing studies, azodicarbonamide is the only biological source of biurea, so biurea can be used as the corresponding target detector of azodicarbonamide. To solve the problem that endogenous and exogenous semicarbazide cannot be distinguished in aquatic products in China, the endogenous and exogenous pathways of semicarbazide and the corresponding possible formation mechanisms are reviewed in this paper. The formation pathways of endogenous semicarbazide are speculated to help solve the formation mechanism of semicarbazide in crustacean aquatic products and provide scientific data for the standardization of semicarbazide residue limits in China.
2025, 46(1):222-230.
DOI: 10.19663/j.issn2095-9869.20240105001
Abstract:
Scomberomorus niphonius, an important marine economic fish in China, is widely distributed in the Bohai, Yellow, and East China Seas. In 2022, the total catch of Scomberomorus niphonius in China was 356,100 tons, representing 3.75% of China's overall marine fish catch. Shandong Province accounted for a significant portion, with a catch of 175,300 tons, constituting 49.22% of the national total. The annual catch of S. niphonius in Shandong ranks first in the country. S. niphonius is rich in protein, unsaturated fatty acids, essential amino acids, minerals, and other nutrients. It has a delicious flavor and is popular with consumers. S. niphonius, during processing and storage, is susceptible to microorganisms, temperature, and other external environmental influences of corruption deterioration and loss of commodity value; therefore, its storage quality must be improved. Among various fish products, vacuum-packed ready-to-eat soft canned products are popular and widely used with high commercial value due to their short sterilization time, low nutritional loss, and easy portability. Sterilization is an important way of ensuring product quality and extending shelf-life. However, the irrationality of the sterilization process, which focuses mainly on the effect of a single sterilization temperature and time on these quality indicators, often results in a reduction in the quality of the product in terms of flavor, texture, and nutritional value. Lipids are important components of seafood and essential biomolecules. They are also involved in organismal processes essential in the nutritional value, texture, and overall organoleptic properties of seafood. For flavor modification, they act as solvents and precursors of volatile compounds. In addition, seafood contains essential nutritional lipids, including phospholipids, triglycerides, and essential fatty acids, which is an important feature distinguishing it from other species. In addition, most of the volatile flavor compounds in meat are produced by the Melad reaction and the thermal degradation of lipids (oxidation) and thiamine. Oxidative degradation of lipids is the main pathway for forming the characteristic flavor of aquatic products. S. niphonius, due to its high content of unsaturated fatty acids, releases unsaturated fatty acids from the lipids during sterilization to further oxidize them into volatile compounds such as aldehydes, ketones, and alcohols, which have a low threshold value and can significantly impact the flavor quality of the product. Currently, the processing of S. niphonius is focused on dry-cured products, and relatively few studies have been conducted on the quality changes during the processing and sterilization of its soft canning. Based on this, the present study took the S. niphonius as a research object and used conventional physicochemical tests combined with the electronic nose, gas chromatography-ion mobility spectrometry (GC-IMS), and other technical means to compare the effects of different sterilization conditions on the physicochemical indices and volatile substances of S. niphonius, to extend its shelf life while reducing the effects of sterilization on its flavor, sensory, and nutritional qualities. This will provide a reference for quality control in the processing of prepared fish dishes and enrich the basic theory of flavor formation in thermally sterilized aquatic products. The results showed that the sensory scores of texture, taste, and odor of S. niphonius changed significantly after sterilization. The total lipid, triglyceride, and phospholipid contents in the samples were significantly decreased after sterilization (P<0.05), and the free fatty acid content was significantly increased (P<0.05). Differences were observed in lipid composition between different sterilization groups, with the highest degree of lipid loss in Group C samples. The degree of lipid oxidation was significantly affected by sterilization conditions (P<0.05), peroxidevalue (POV) content was significantly increased, and thiobarbituric acid reactive substances (TBARS) content was significantly decreased (P<0.05). The results of electronic nose analysis showed that the odor characteristics of fish meat after different sterilization conditions were significantly different. Twenty-two volatile compounds were identified from the four groups of samples using GC-IMS, including seven aldehydes, five ketones, four alcohols, three esters, two acids, and one furan. Among these compounds, heptyl aldehyde, hexaldehyde, 3-hydroxybutane-2-ketone, acetic acid, and 1-octene-3-alcohol were identified as the primary volatile substances in the control group. The signal intensity of valeraldehyde, isovaleraldehyde, butyraldehyde, 3-hydroxy-butanone, and ethyl propionate significantly increased after the fish underwent various sterilization conditions. This observation suggests that sterilization promotes lipid oxidation and decomposition in fish while leading to significant variations in volatile substance profiles among different sterilization processes. Hexanal, pentanal, 2-methylbutanal, 3-pentanone, cyclohexanone, 3-hydroxybutan-2-one, and ethyl acetate were the major aroma compounds in the fish, and the highest levels were found in the samples from Group B. In conclusion, the organoleptic and flavor qualities of the samples at 115 ℃ for 14.7 min (Group B) were significantly better than those of the other sterilization conditions, and the degree of lipid oxidation was lower, which provides technical support for the fine processing of S. niphonius products.
Scomberomorus niphonius, an important marine economic fish in China, is widely distributed in the Bohai, Yellow, and East China Seas. In 2022, the total catch of Scomberomorus niphonius in China was 356,100 tons, representing 3.75% of China's overall marine fish catch. Shandong Province accounted for a significant portion, with a catch of 175,300 tons, constituting 49.22% of the national total. The annual catch of S. niphonius in Shandong ranks first in the country. S. niphonius is rich in protein, unsaturated fatty acids, essential amino acids, minerals, and other nutrients. It has a delicious flavor and is popular with consumers. S. niphonius, during processing and storage, is susceptible to microorganisms, temperature, and other external environmental influences of corruption deterioration and loss of commodity value; therefore, its storage quality must be improved. Among various fish products, vacuum-packed ready-to-eat soft canned products are popular and widely used with high commercial value due to their short sterilization time, low nutritional loss, and easy portability. Sterilization is an important way of ensuring product quality and extending shelf-life. However, the irrationality of the sterilization process, which focuses mainly on the effect of a single sterilization temperature and time on these quality indicators, often results in a reduction in the quality of the product in terms of flavor, texture, and nutritional value. Lipids are important components of seafood and essential biomolecules. They are also involved in organismal processes essential in the nutritional value, texture, and overall organoleptic properties of seafood. For flavor modification, they act as solvents and precursors of volatile compounds. In addition, seafood contains essential nutritional lipids, including phospholipids, triglycerides, and essential fatty acids, which is an important feature distinguishing it from other species. In addition, most of the volatile flavor compounds in meat are produced by the Melad reaction and the thermal degradation of lipids (oxidation) and thiamine. Oxidative degradation of lipids is the main pathway for forming the characteristic flavor of aquatic products. S. niphonius, due to its high content of unsaturated fatty acids, releases unsaturated fatty acids from the lipids during sterilization to further oxidize them into volatile compounds such as aldehydes, ketones, and alcohols, which have a low threshold value and can significantly impact the flavor quality of the product. Currently, the processing of S. niphonius is focused on dry-cured products, and relatively few studies have been conducted on the quality changes during the processing and sterilization of its soft canning. Based on this, the present study took the S. niphonius as a research object and used conventional physicochemical tests combined with the electronic nose, gas chromatography-ion mobility spectrometry (GC-IMS), and other technical means to compare the effects of different sterilization conditions on the physicochemical indices and volatile substances of S. niphonius, to extend its shelf life while reducing the effects of sterilization on its flavor, sensory, and nutritional qualities. This will provide a reference for quality control in the processing of prepared fish dishes and enrich the basic theory of flavor formation in thermally sterilized aquatic products. The results showed that the sensory scores of texture, taste, and odor of S. niphonius changed significantly after sterilization. The total lipid, triglyceride, and phospholipid contents in the samples were significantly decreased after sterilization (P<0.05), and the free fatty acid content was significantly increased (P<0.05). Differences were observed in lipid composition between different sterilization groups, with the highest degree of lipid loss in Group C samples. The degree of lipid oxidation was significantly affected by sterilization conditions (P<0.05), peroxidevalue (POV) content was significantly increased, and thiobarbituric acid reactive substances (TBARS) content was significantly decreased (P<0.05). The results of electronic nose analysis showed that the odor characteristics of fish meat after different sterilization conditions were significantly different. Twenty-two volatile compounds were identified from the four groups of samples using GC-IMS, including seven aldehydes, five ketones, four alcohols, three esters, two acids, and one furan. Among these compounds, heptyl aldehyde, hexaldehyde, 3-hydroxybutane-2-ketone, acetic acid, and 1-octene-3-alcohol were identified as the primary volatile substances in the control group. The signal intensity of valeraldehyde, isovaleraldehyde, butyraldehyde, 3-hydroxy-butanone, and ethyl propionate significantly increased after the fish underwent various sterilization conditions. This observation suggests that sterilization promotes lipid oxidation and decomposition in fish while leading to significant variations in volatile substance profiles among different sterilization processes. Hexanal, pentanal, 2-methylbutanal, 3-pentanone, cyclohexanone, 3-hydroxybutan-2-one, and ethyl acetate were the major aroma compounds in the fish, and the highest levels were found in the samples from Group B. In conclusion, the organoleptic and flavor qualities of the samples at 115 ℃ for 14.7 min (Group B) were significantly better than those of the other sterilization conditions, and the degree of lipid oxidation was lower, which provides technical support for the fine processing of S. niphonius products.
JIANG Xiaodong
,
WANG Ying
,
HOU Fusheng
,
LI Hongyan
,
ZHANG Shuaizhong
,
SUN Yuanqin
,
LIU Tianhong
2024, 45(5):234-244.
DOI: 10.19663/j.issn2095-9869.20240527002
Abstract:
Oncorhynchus mykiss is a high-quality, edible fish with high nutritional and economic value. Its tender meat, full elasticity, delicious flavor, and rich nutritional value make it favorite among consumers. However, owing to its high water and fat content and high enzymatic activity, O. mykiss is highly susceptible to spoilage during storage, transportation, and sale. To study the effects of different pretreatment methods on the quality of O. mykiss during storage and slow its decay rate, experiments were conducted with two pretreatment groups: Cold saltwater group (salt content 3%, temperature 4 ℃) and slightly acid electrolyzed water group (pH 6.35, ORP 900 mV, ACC 50 mg/L, room temperature). Different pretreatment times were set for each group: 20 min, 40 min, and 60 min of cold saltwater treatment and 5 min, 10 min, and 15 min of slightly acid electrolyzed water treatment. TVB-N value, total bacterial count, water holding capacity, cooking loss rate, pH value, chromaticity, and sensory evaluation were measured as indicators, and untreated O. mykiss meat was used as a control to compare the changes of the quality of O. mykiss meat during a 9-day storage experiment at 4 ℃. The results showed that the optimal pretreatment times were 60 min for the cold saltwater pretreatment and 10 min for the slightly acid electrolyzed water pretreatment. Both preprocessing methods can effectively maintain the freshness of O. mykiss and delay its spoilage. Compared with the cold saltwater pretreatment, the slightly acid electrolyzed water treatment better inhibited the total bacterial count and TVB-N generation of O. mykiss, maintaining its water-holding capacity and delaying the rate of change of pH, chromaticity, and sensory properties during storage. Cold saltwater pretreatment can extend the refrigerated shelf life of O. mykiss by 1 day, whereas slightly acid electrolyzed water pretreatment can extend the shelf life by 2 days. Overall, pretreatment with slightly acid electrolyzed water for 10 min can effectively improve the preservation quality of O. mykiss stored at 4 ℃. Slightly acid electrolyzed water has enormous potential for applications in the preservation of aquatic products. Its unique sterilization effect and safety make it preferred for aquatic product preservation. Slightly acid electrolyzed water can effectively inhibit the growth of microorganisms in aquatic products, extend shelf life, and maintain the freshness and taste of aquatic products. In the future, with advancements in technology and increasing awareness of food safety among consumers, slightly acid electrolyzed water will play an important role in the preservation of aquatic products, providing strong guarantees for the quality and safety of aquatic products.
Oncorhynchus mykiss is a high-quality, edible fish with high nutritional and economic value. Its tender meat, full elasticity, delicious flavor, and rich nutritional value make it favorite among consumers. However, owing to its high water and fat content and high enzymatic activity, O. mykiss is highly susceptible to spoilage during storage, transportation, and sale. To study the effects of different pretreatment methods on the quality of O. mykiss during storage and slow its decay rate, experiments were conducted with two pretreatment groups: Cold saltwater group (salt content 3%, temperature 4 ℃) and slightly acid electrolyzed water group (pH 6.35, ORP 900 mV, ACC 50 mg/L, room temperature). Different pretreatment times were set for each group: 20 min, 40 min, and 60 min of cold saltwater treatment and 5 min, 10 min, and 15 min of slightly acid electrolyzed water treatment. TVB-N value, total bacterial count, water holding capacity, cooking loss rate, pH value, chromaticity, and sensory evaluation were measured as indicators, and untreated O. mykiss meat was used as a control to compare the changes of the quality of O. mykiss meat during a 9-day storage experiment at 4 ℃. The results showed that the optimal pretreatment times were 60 min for the cold saltwater pretreatment and 10 min for the slightly acid electrolyzed water pretreatment. Both preprocessing methods can effectively maintain the freshness of O. mykiss and delay its spoilage. Compared with the cold saltwater pretreatment, the slightly acid electrolyzed water treatment better inhibited the total bacterial count and TVB-N generation of O. mykiss, maintaining its water-holding capacity and delaying the rate of change of pH, chromaticity, and sensory properties during storage. Cold saltwater pretreatment can extend the refrigerated shelf life of O. mykiss by 1 day, whereas slightly acid electrolyzed water pretreatment can extend the shelf life by 2 days. Overall, pretreatment with slightly acid electrolyzed water for 10 min can effectively improve the preservation quality of O. mykiss stored at 4 ℃. Slightly acid electrolyzed water has enormous potential for applications in the preservation of aquatic products. Its unique sterilization effect and safety make it preferred for aquatic product preservation. Slightly acid electrolyzed water can effectively inhibit the growth of microorganisms in aquatic products, extend shelf life, and maintain the freshness and taste of aquatic products. In the future, with advancements in technology and increasing awareness of food safety among consumers, slightly acid electrolyzed water will play an important role in the preservation of aquatic products, providing strong guarantees for the quality and safety of aquatic products.
2023, 44(2):205-213.
DOI: 10.19663/j.issn2095-9869.20210924002
Abstract:
Channa argus is a bottom-dwelling freshwater fish with high nutritional and economic value and, in China, is known as the "treasure of fish”. C. argus meat is mainly used to produce fish fillets; however, head and bone are occasionally utilized in food production. The head of C. argus is rich in mineral elements, amino acids, and unsaturated fatty acids and is commonly used in China for fish head soup. The preparation of fish head soup is particularly time-consuming and can take several hours. Therefore, a high demand exists for the research and development of instant fish head soup products. With the development of modern food colloid research technology, the formation of micro/nanoparticles (MNPs) in soups and the biological effects of the tissue units as active ingredients have attracted increasing attention. In terms of the cooking process of fish soup, in addition to the heating method and cooking time, the seasoning added during cooking is also an important factor. In particular, salt is a key determinant of soup flavor. Although the content is the same, the addition of salt affects the dissolution and migration of nutrients from the fish head during the cooking process. However, the effect of the addition time of salt on the nutritious flavor during the preparation of fish soup has not been studied clearly. Furthermore, the stability of fish soup has not been adequately evaluated. In this work, the C. argus head was chosen as the base material for the soup and the nutrient migration and particles in the C. argus head soup were studied. Water-soluble protein, total sugar, total minerals, solids, nucleotides, free amino acid content, and colloidal particle stability were chosen as indicators to evaluate the transfer of nutrients and flavor. In addition, the morphological structure and distribution of MNPs in the soup were observed using laser scanning confocal microscopy (LSCM). The results showed that the content of water-soluble proteins first increased and then decreased with the delay in salt addition time. The migration trend of total sugars was similar to that of the proteins. Meanwhile, the ash content in the soup generally increased and then decreased. The change in the content of soluble solids could represent changes in various nutrients. The migration of solids and the content of ash peaked when the salting time was at 90 min. The boiled samples with salt added at different times showed significant differences in the migration of nucleotides. It could be concluded that salting was ideal at 60 min or 90 min, based on the changes in the total amount of nucleotides. Furthermore, the contents of total free amino acids and umami-flavored amino acids were also the highest in the samples with salt added at 60 min or 90 min. When the addition time was 60 min, the stability of the MNP system in the fish head soup could effectively be improved by inhibiting the aggregation of macromolecules, which would promote the retention of various nutrients. The particle size and polydispersity (PDI) were lowest in the samples with salt added at 60 min. In addition, the zeta potential value of the sample with salt added at 60 min was higher than that at 90 min. Therefore, the system was relatively stable at 60 min, which was conducive to nutrient retention. This is consistent with the results of the microstructure analysis. The maximum dissolution of nutrients and flavor substances occurred when salt was added after boiling for 60 min. Meanwhile, MNPs in the soup were stable, uniform, double-layer, spherical particles. The results of LSCM showed that nonpolar triglycerides self-assembled into spherical particles, which were located in the center of the particles, and protein molecules dispersed around or were bound to the surface of the particles. The fish head soup system was the most stable under the conditions of particle size, potential, and polydispersion index. Therefore, adding salt after boiling for 60 min was the optimal procedure for making fish soup with high nutritional value, delicious taste, and stable content. This study provides a baseline procedure for C. argus head soup with high and stable nutritional content. The results provide technical support for preparing a convenient and delicious fish head soup. People can enjoy delicious food shortly after a hard day´s work. In addition, the results showed that the timing of adding salt had a significant impact on the nutrition of fish head soup, which suggests that attention should be paid to the timing of adding salt when preparing fish head soup at home. C. argus head, a by-product of processing, can increase in value and provide a solution for producers to decrease waste and increase profits.
Channa argus is a bottom-dwelling freshwater fish with high nutritional and economic value and, in China, is known as the "treasure of fish”. C. argus meat is mainly used to produce fish fillets; however, head and bone are occasionally utilized in food production. The head of C. argus is rich in mineral elements, amino acids, and unsaturated fatty acids and is commonly used in China for fish head soup. The preparation of fish head soup is particularly time-consuming and can take several hours. Therefore, a high demand exists for the research and development of instant fish head soup products. With the development of modern food colloid research technology, the formation of micro/nanoparticles (MNPs) in soups and the biological effects of the tissue units as active ingredients have attracted increasing attention. In terms of the cooking process of fish soup, in addition to the heating method and cooking time, the seasoning added during cooking is also an important factor. In particular, salt is a key determinant of soup flavor. Although the content is the same, the addition of salt affects the dissolution and migration of nutrients from the fish head during the cooking process. However, the effect of the addition time of salt on the nutritious flavor during the preparation of fish soup has not been studied clearly. Furthermore, the stability of fish soup has not been adequately evaluated. In this work, the C. argus head was chosen as the base material for the soup and the nutrient migration and particles in the C. argus head soup were studied. Water-soluble protein, total sugar, total minerals, solids, nucleotides, free amino acid content, and colloidal particle stability were chosen as indicators to evaluate the transfer of nutrients and flavor. In addition, the morphological structure and distribution of MNPs in the soup were observed using laser scanning confocal microscopy (LSCM). The results showed that the content of water-soluble proteins first increased and then decreased with the delay in salt addition time. The migration trend of total sugars was similar to that of the proteins. Meanwhile, the ash content in the soup generally increased and then decreased. The change in the content of soluble solids could represent changes in various nutrients. The migration of solids and the content of ash peaked when the salting time was at 90 min. The boiled samples with salt added at different times showed significant differences in the migration of nucleotides. It could be concluded that salting was ideal at 60 min or 90 min, based on the changes in the total amount of nucleotides. Furthermore, the contents of total free amino acids and umami-flavored amino acids were also the highest in the samples with salt added at 60 min or 90 min. When the addition time was 60 min, the stability of the MNP system in the fish head soup could effectively be improved by inhibiting the aggregation of macromolecules, which would promote the retention of various nutrients. The particle size and polydispersity (PDI) were lowest in the samples with salt added at 60 min. In addition, the zeta potential value of the sample with salt added at 60 min was higher than that at 90 min. Therefore, the system was relatively stable at 60 min, which was conducive to nutrient retention. This is consistent with the results of the microstructure analysis. The maximum dissolution of nutrients and flavor substances occurred when salt was added after boiling for 60 min. Meanwhile, MNPs in the soup were stable, uniform, double-layer, spherical particles. The results of LSCM showed that nonpolar triglycerides self-assembled into spherical particles, which were located in the center of the particles, and protein molecules dispersed around or were bound to the surface of the particles. The fish head soup system was the most stable under the conditions of particle size, potential, and polydispersion index. Therefore, adding salt after boiling for 60 min was the optimal procedure for making fish soup with high nutritional value, delicious taste, and stable content. This study provides a baseline procedure for C. argus head soup with high and stable nutritional content. The results provide technical support for preparing a convenient and delicious fish head soup. People can enjoy delicious food shortly after a hard day´s work. In addition, the results showed that the timing of adding salt had a significant impact on the nutrition of fish head soup, which suggests that attention should be paid to the timing of adding salt when preparing fish head soup at home. C. argus head, a by-product of processing, can increase in value and provide a solution for producers to decrease waste and increase profits.
2025, 46(1):210-221.
DOI: 10.19663/j.issn2095-9869.20240305002
Abstract:
The golden pomfret (Trachinotus ovatus) is distributed in tropical and subtropical waters such as those of the East China Sea, South China Sea, and the Chinese Yellow and Bohai Seas. The golden pomfret grows rapidly and is the most modernized and intensive marine aquaculture fish in China. Furthermore, the golden pomfret is also the preferred variety of fish for expanding sea aquaculture spaces. Presently, the market mainly includes three methods: Freezing, processing, and live sales. If fish can be processed in multiple ways while maintaining freshness, fresh fish is the best choice. However, the existing transportation of live fish suffers from various problems such as low survival rate, nutrient loss, and short transportation time due to stress, hypoxia, and water quality deterioration. T. ovatus is a warm temperature-loving, omnivorous migratory fish with high oxygen consumption and vigorous metabolism. Fishing exerts high stress on the organism, and they easily die in low temperature environments (<13 ℃). The difficulty of keeping the fish alive and transporting is also the main reason live fish are difficult to find in markets. To solve the above problems, chemical anesthesia, physical dormancy, and other methods are generally used to improve the survival rate of fish and maintain good nutritional quality in the process of keeping them alive and for transportation. Chemical anesthesia may pose risks of drug residue, and there are certain restrictions on the drug withdrawal period for the fish to be transported alive. Among the physical dormancy methods, the ecological ice temperature induced dormancy method is widely used, but it needs low temperature acclimation before treatment, which consumes long time periods. Therefore, an efficient, green and safe way of keeping alive transportation technology is particularly urgent, and corona dormancy presents an environment friendly, safe, new, and efficient way of physical dormancy that meets consumer needs, with broad application prospects. Chemical anesthesia and low temperature-induced dormancy are mostly used in the pretreatment technology of survival and transportation of marine fish, while the research on corona dormancy technology is less, and the research and application of corona dormant T. ovatus have not been reported locally or abroad. In this study, T. ovatus were placed in an electric shock box after 6 h of temporary rearing. The T. ovatus were shocked by pulsed DC currents. The recovery phase was recorded by stages through behavioral observation. The optimal treatment conditions of pulsed DC corona dormancy were optimized by using the dormancy rate, dormancy time, 72 h survival rate and survival time as evaluation indexes through single factor and orthogonal experiments, and the biochemical parameters of serum, brain tissue, muscle and liver are determined indexes of oxidative stress, metabolism, and basic nutrients. The results showed that under the conditions of 20 ℃ water temperature, 140 V voltage, and 4 s treatment time, the dormancy rate and 72 h survival rate of fish could reach 100%, and the survival time was (165.6±42.7) h. After corona dormancy treatment, the contents of glucose (GLU), glutamic oxaloacetic transaminase (GOT), and cortisol (COR) in fish serum significantly increased (P<0.05), and return to normal levels within 4–12 hours of survival, indicating that electrical stimulation can make the life activities of fish become violent, resulting in the rise of stress indicators in a short time. The content of heat shock protein 70 (Hsp70), glutathione S-transferase (GST-S) activity, and catalase (CAT) activity in liver and brain tissues significantly increased (P<0.05), while the content of malondialdehyde (MDA) in brain tissues was significantly decreased compared with that in the control group within 4–72 hours (P<0.05), indicating that the technology can improve the tolerance of fish to environmental stress and reduce the degree of brain damage, reduce the lipid peroxidation in the brain and the accumulation of hydrogen peroxide in the liver, so as to reduce the damage cause by environmental stress and short-term damage to tissues. The content of liver glycogen (Gly) show a downward trend during the preservation process, while the content of lactic acid (LD) in liver and muscle increase significantly (P<0.05), indicating that anaerobic metabolism occurs during the preservation process of fasting, which consume glycogen and produced lactic acid. Crude ash, protein, and fat in fish meat show a downward trend during the preservation process, with the crude fat content decreased the most significantly (P<0.05), and the proportion of decline in the experimental group was reduced compared with that of the control group. The research shows that the appropriate conditions of pulsed DC can induce the dormancy of T. ovatus, and after corona dormancy fish exhibit less stress in the face of external factors. From the index point of view, the technology can improve the release of Hsp70 and the activity of antioxidant enzymes to slow the stress response of the fish under survival stress, reduce tissue damage, and maintain a low metabolic level after survival, reducing the consumption of inorganic matter, fat, and protein. Thus, the efficiency and quality in the process of keeping alive transportation are improving, which is convenient for breeding and transportation. Finally, these findings lay a theoretical foundation for maintaining the vitality and quality of T. ovatus.
The golden pomfret (Trachinotus ovatus) is distributed in tropical and subtropical waters such as those of the East China Sea, South China Sea, and the Chinese Yellow and Bohai Seas. The golden pomfret grows rapidly and is the most modernized and intensive marine aquaculture fish in China. Furthermore, the golden pomfret is also the preferred variety of fish for expanding sea aquaculture spaces. Presently, the market mainly includes three methods: Freezing, processing, and live sales. If fish can be processed in multiple ways while maintaining freshness, fresh fish is the best choice. However, the existing transportation of live fish suffers from various problems such as low survival rate, nutrient loss, and short transportation time due to stress, hypoxia, and water quality deterioration. T. ovatus is a warm temperature-loving, omnivorous migratory fish with high oxygen consumption and vigorous metabolism. Fishing exerts high stress on the organism, and they easily die in low temperature environments (<13 ℃). The difficulty of keeping the fish alive and transporting is also the main reason live fish are difficult to find in markets. To solve the above problems, chemical anesthesia, physical dormancy, and other methods are generally used to improve the survival rate of fish and maintain good nutritional quality in the process of keeping them alive and for transportation. Chemical anesthesia may pose risks of drug residue, and there are certain restrictions on the drug withdrawal period for the fish to be transported alive. Among the physical dormancy methods, the ecological ice temperature induced dormancy method is widely used, but it needs low temperature acclimation before treatment, which consumes long time periods. Therefore, an efficient, green and safe way of keeping alive transportation technology is particularly urgent, and corona dormancy presents an environment friendly, safe, new, and efficient way of physical dormancy that meets consumer needs, with broad application prospects. Chemical anesthesia and low temperature-induced dormancy are mostly used in the pretreatment technology of survival and transportation of marine fish, while the research on corona dormancy technology is less, and the research and application of corona dormant T. ovatus have not been reported locally or abroad. In this study, T. ovatus were placed in an electric shock box after 6 h of temporary rearing. The T. ovatus were shocked by pulsed DC currents. The recovery phase was recorded by stages through behavioral observation. The optimal treatment conditions of pulsed DC corona dormancy were optimized by using the dormancy rate, dormancy time, 72 h survival rate and survival time as evaluation indexes through single factor and orthogonal experiments, and the biochemical parameters of serum, brain tissue, muscle and liver are determined indexes of oxidative stress, metabolism, and basic nutrients. The results showed that under the conditions of 20 ℃ water temperature, 140 V voltage, and 4 s treatment time, the dormancy rate and 72 h survival rate of fish could reach 100%, and the survival time was (165.6±42.7) h. After corona dormancy treatment, the contents of glucose (GLU), glutamic oxaloacetic transaminase (GOT), and cortisol (COR) in fish serum significantly increased (P<0.05), and return to normal levels within 4–12 hours of survival, indicating that electrical stimulation can make the life activities of fish become violent, resulting in the rise of stress indicators in a short time. The content of heat shock protein 70 (Hsp70), glutathione S-transferase (GST-S) activity, and catalase (CAT) activity in liver and brain tissues significantly increased (P<0.05), while the content of malondialdehyde (MDA) in brain tissues was significantly decreased compared with that in the control group within 4–72 hours (P<0.05), indicating that the technology can improve the tolerance of fish to environmental stress and reduce the degree of brain damage, reduce the lipid peroxidation in the brain and the accumulation of hydrogen peroxide in the liver, so as to reduce the damage cause by environmental stress and short-term damage to tissues. The content of liver glycogen (Gly) show a downward trend during the preservation process, while the content of lactic acid (LD) in liver and muscle increase significantly (P<0.05), indicating that anaerobic metabolism occurs during the preservation process of fasting, which consume glycogen and produced lactic acid. Crude ash, protein, and fat in fish meat show a downward trend during the preservation process, with the crude fat content decreased the most significantly (P<0.05), and the proportion of decline in the experimental group was reduced compared with that of the control group. The research shows that the appropriate conditions of pulsed DC can induce the dormancy of T. ovatus, and after corona dormancy fish exhibit less stress in the face of external factors. From the index point of view, the technology can improve the release of Hsp70 and the activity of antioxidant enzymes to slow the stress response of the fish under survival stress, reduce tissue damage, and maintain a low metabolic level after survival, reducing the consumption of inorganic matter, fat, and protein. Thus, the efficiency and quality in the process of keeping alive transportation are improving, which is convenient for breeding and transportation. Finally, these findings lay a theoretical foundation for maintaining the vitality and quality of T. ovatus.
8 The construction of a low-odor background model of silver carp (Hypophthalmichthys molitrix) surimi
GENG Haiyong
,
CHEN Lihua
,
YANG Fang
,
WU Yi
,
WANG Shufen
,
JIANG Qixing
,
XU Yanshun
,
XIA Wenshui
2024, 45(3):245-257.
DOI: 10.19663/j.issn2095-9869.20230314002
Abstract:
In the Healthy China Strategy context, fish are increasingly in demand as a source of high-quality protein. Silver carp (Hypophthalmichthys molitrix) is a resource-rich and highly productive freshwater fish species found in China that is not edible raw or cooked in its original form due to its many boney spines. However, due to its advantages of being low-cost, low in fat, and high in protein, it is an ideal choice for surimi production. Currently, it is widely used in the industrial production of surimi products. The development of the freshwater surimi industry can significantly improve the added value of freshwater fish utilization, which has attracted extensive attention. Freshwater surimi is high in protein and low in fat and has a smooth and delicate taste, making it extremely popular with consumers. It has a high output, low price, is growing in demand, and is gradually being accepted throughout domestic and foreign markets. It has also driven the development of some related industries and produced significant economic and social benefits. As domestic consumers experience improved living standards and a faster pace of work, premade dishes containing surimi products as well as recreational snack surimi products with increased shelf-life are more attractive, as they save the consumer processing time, are enjoyed by the consumer, and meet their nutritional demands, affording these products great market potential. With the development of surimi products and related industries, specific requirements are being put forward for its production. Although China supplanted Japan as the largest producer of surimi products worldwide in 2006, ushering in a period of nearly 10 years of high production growth, the annual production of surimi products in China since 2014 has stagnated or even slightly decreased. Moreover, the surimi industry has entered a bottleneck period for quality enhancement caused by the expansion of quantity. The fishy odor of freshwater surimi is one of the industrial problems that affect the quality and efficiency of surimi. The flavor of surimi products (such as fish balls, fish intestines, fish cakes, and others in hot pot) has become one of the quality attributes that consumers are extremely concerned about. However, the adsorption and release laws of key odor-active substances are still unclear. There are existing research technologies for surimi odor, mainly including instrumental analysis (gas chromatography-mass spectrum, gas chromatography-olfactometry, gas chromatography-olfactometry- mass spectrum, electronic nose technology, etc.), sensomics analysis (odor activity value (OAV), aroma extract dilution analysis, odor recombination, odor omission test, etc.), and enzyme-linked immunosorbent assay. The research objects of odor sensory experiments are mostly rice wine, oil, vegetables, fruits, and fungi. Moreover, present odor research is mainly carried out in a prepared solution, mainly using odor recombination of a liquid simulation system, which is different from the interaction between the real odor active substance-solid surimi. Therefore, constructing an odor model based on solid surimi is necessary to better simulate the sensory characteristics of surimi. To build an odor model based on solid surimi, an odorless or low-odor surimi background model must be established in order to investigate the interaction between various odor components and surimi. There are several fishy substances and complex components in freshwater fish and surimi products, including aldehydes, alcohols, ketones, esters, sulfur compounds, nitrogen compounds, and alkanes. At present, most studies on rinsing surimi reported worldwide are based on how to better apply it to the food system, ignoring interactions between components in the complex system of surimi, which creates certain limitations in establishing a background model of surimi. Therefore, salt, salt-alcohol, acid, alkali, and other rinsing media were selected in this study, which was not limited to food systems. By comparing the removal effects of different rinsing media on the odor residue of surimi, an odorless or low-odor background model of surimi could be constructed. Here, the effect of different rinsing media on the odor residue of a surimi background model was studied. Specific rinsing media were as follows: 0.5% NaCl (W/W) + 0.35% Na2CO3 (W/W) + 4.0% C2H5OH (W/W) solution (group A), 0.5% NaCl (W/W) + 0.35% Na2CO3 solution (group B), 0.5% CaCl2 (W/W) + 0.35% Na2CO3 (W/W) + 4.0% C2H5OH (V/W) solution (group C), 0.5% CaCl2 (W/W) + 0.35% Na2CO3 (W/W) solution (group D), 1% NaCl (W/W) + 1% Na2CO3 (W/W) + 4.0% C2H5OH (V/W) solution (group E), 1% NaCl (W/W) + 1% Na2CO3 (W/W) solution (group F), 1 mol/L HCl solution (group G), and 1 mol/L NaOH solution (group H), respectively. The results showed that SPME-GC-MS detected 65 volatile compounds in silver carp surimi, including 22 aldehydes, 13 alcohols, 9 ketones, and 7 hydrocarbons, among which the contents of aldehydes and alcohols were high, which had a major contribution to the odor of silver carp surimi. A total of 18 odor-active substances were detected by the OAV (≥1) method, which helped illustrate that odor-active compounds contribute to the overall odor of surimi. After treatment with eight kinds of rinsing media, the residual amount of the odor-active substances in the silver carp surimi was washed or released to varying degrees, affecting the sample's overall odor contribution. The rinsed surimi samples contained 6, 8, 7, 9, 6, 12, 9, and 9 odor active compounds and residual rates of volatile odor compounds were (0.380±0.120)%, (0.610±0.086)%, (0.280±0.033)%, (0.480±0.037)%, (0.150±0.018)%, (4.330±0.160)%, (18.680±0.081)%, and (0.490±0.003)%, respectively. According to the SPME-GC-MS analysis results, due to the synergistic effect of ethanol, the content of volatile compounds detected in group E was the lowest, the total residual amount of odor-active compounds was reduced to (6.57±0.77) μg/kg, and the total residue rate was only 0.15%. Meanwhile, the total OAV decreased to 2.52±0.25, there were 17 odor-active substances with an OAV<1, and the OAV of nonanal was only 1.34±0.05, which could establish a low-odor background model of surimi. Furthermore, electronic nose and sensory evaluations distinguished the overall odor characteristics between different rinsed samples and fresh surimi. This study took silver carp surimi as the research object and studied the influence of volatile odor compounds and salts, salt-alcohols, acids, alkalis, and other rinsing media in surimi on the residual rate of odor substances through SPME-GC-MS, electronic nose, and sensory evaluation methods, which will significantly contribute to the establishment of an odorless or low-odor solid surimi model and provide a novel idea for sensory analysis.
In the Healthy China Strategy context, fish are increasingly in demand as a source of high-quality protein. Silver carp (Hypophthalmichthys molitrix) is a resource-rich and highly productive freshwater fish species found in China that is not edible raw or cooked in its original form due to its many boney spines. However, due to its advantages of being low-cost, low in fat, and high in protein, it is an ideal choice for surimi production. Currently, it is widely used in the industrial production of surimi products. The development of the freshwater surimi industry can significantly improve the added value of freshwater fish utilization, which has attracted extensive attention. Freshwater surimi is high in protein and low in fat and has a smooth and delicate taste, making it extremely popular with consumers. It has a high output, low price, is growing in demand, and is gradually being accepted throughout domestic and foreign markets. It has also driven the development of some related industries and produced significant economic and social benefits. As domestic consumers experience improved living standards and a faster pace of work, premade dishes containing surimi products as well as recreational snack surimi products with increased shelf-life are more attractive, as they save the consumer processing time, are enjoyed by the consumer, and meet their nutritional demands, affording these products great market potential. With the development of surimi products and related industries, specific requirements are being put forward for its production. Although China supplanted Japan as the largest producer of surimi products worldwide in 2006, ushering in a period of nearly 10 years of high production growth, the annual production of surimi products in China since 2014 has stagnated or even slightly decreased. Moreover, the surimi industry has entered a bottleneck period for quality enhancement caused by the expansion of quantity. The fishy odor of freshwater surimi is one of the industrial problems that affect the quality and efficiency of surimi. The flavor of surimi products (such as fish balls, fish intestines, fish cakes, and others in hot pot) has become one of the quality attributes that consumers are extremely concerned about. However, the adsorption and release laws of key odor-active substances are still unclear. There are existing research technologies for surimi odor, mainly including instrumental analysis (gas chromatography-mass spectrum, gas chromatography-olfactometry, gas chromatography-olfactometry- mass spectrum, electronic nose technology, etc.), sensomics analysis (odor activity value (OAV), aroma extract dilution analysis, odor recombination, odor omission test, etc.), and enzyme-linked immunosorbent assay. The research objects of odor sensory experiments are mostly rice wine, oil, vegetables, fruits, and fungi. Moreover, present odor research is mainly carried out in a prepared solution, mainly using odor recombination of a liquid simulation system, which is different from the interaction between the real odor active substance-solid surimi. Therefore, constructing an odor model based on solid surimi is necessary to better simulate the sensory characteristics of surimi. To build an odor model based on solid surimi, an odorless or low-odor surimi background model must be established in order to investigate the interaction between various odor components and surimi. There are several fishy substances and complex components in freshwater fish and surimi products, including aldehydes, alcohols, ketones, esters, sulfur compounds, nitrogen compounds, and alkanes. At present, most studies on rinsing surimi reported worldwide are based on how to better apply it to the food system, ignoring interactions between components in the complex system of surimi, which creates certain limitations in establishing a background model of surimi. Therefore, salt, salt-alcohol, acid, alkali, and other rinsing media were selected in this study, which was not limited to food systems. By comparing the removal effects of different rinsing media on the odor residue of surimi, an odorless or low-odor background model of surimi could be constructed. Here, the effect of different rinsing media on the odor residue of a surimi background model was studied. Specific rinsing media were as follows: 0.5% NaCl (W/W) + 0.35% Na2CO3 (W/W) + 4.0% C2H5OH (W/W) solution (group A), 0.5% NaCl (W/W) + 0.35% Na2CO3 solution (group B), 0.5% CaCl2 (W/W) + 0.35% Na2CO3 (W/W) + 4.0% C2H5OH (V/W) solution (group C), 0.5% CaCl2 (W/W) + 0.35% Na2CO3 (W/W) solution (group D), 1% NaCl (W/W) + 1% Na2CO3 (W/W) + 4.0% C2H5OH (V/W) solution (group E), 1% NaCl (W/W) + 1% Na2CO3 (W/W) solution (group F), 1 mol/L HCl solution (group G), and 1 mol/L NaOH solution (group H), respectively. The results showed that SPME-GC-MS detected 65 volatile compounds in silver carp surimi, including 22 aldehydes, 13 alcohols, 9 ketones, and 7 hydrocarbons, among which the contents of aldehydes and alcohols were high, which had a major contribution to the odor of silver carp surimi. A total of 18 odor-active substances were detected by the OAV (≥1) method, which helped illustrate that odor-active compounds contribute to the overall odor of surimi. After treatment with eight kinds of rinsing media, the residual amount of the odor-active substances in the silver carp surimi was washed or released to varying degrees, affecting the sample's overall odor contribution. The rinsed surimi samples contained 6, 8, 7, 9, 6, 12, 9, and 9 odor active compounds and residual rates of volatile odor compounds were (0.380±0.120)%, (0.610±0.086)%, (0.280±0.033)%, (0.480±0.037)%, (0.150±0.018)%, (4.330±0.160)%, (18.680±0.081)%, and (0.490±0.003)%, respectively. According to the SPME-GC-MS analysis results, due to the synergistic effect of ethanol, the content of volatile compounds detected in group E was the lowest, the total residual amount of odor-active compounds was reduced to (6.57±0.77) μg/kg, and the total residue rate was only 0.15%. Meanwhile, the total OAV decreased to 2.52±0.25, there were 17 odor-active substances with an OAV<1, and the OAV of nonanal was only 1.34±0.05, which could establish a low-odor background model of surimi. Furthermore, electronic nose and sensory evaluations distinguished the overall odor characteristics between different rinsed samples and fresh surimi. This study took silver carp surimi as the research object and studied the influence of volatile odor compounds and salts, salt-alcohols, acids, alkalis, and other rinsing media in surimi on the residual rate of odor substances through SPME-GC-MS, electronic nose, and sensory evaluation methods, which will significantly contribute to the establishment of an odorless or low-odor solid surimi model and provide a novel idea for sensory analysis.
LI Jiaoni
,
ZANG Zhan
,
LIAO Xiurui
,
LI Xi
,
LÜ Bu
,
YANG Shouguo
,
VASQUEZ Herbert Ely
,
GU Zhifeng
,
ZHENG Xing
,
WANG Aimin
2023, 44(5):211-218.
DOI: 10.19663/j.issn2095-9869.20220320001
Abstract:
At present, the research on the physiological effects of transportation activities on aquatic organisms mainly focuses on fish, crustaceans and echinoderms. There are lacking details for transportation effect on Pteria penguin. In order to explore the effects of transportation modes on the survival, growth, digestion and antioxidant properties of P. penguin juveniles, this study was carried out under the conditions of transportation with water and without water, respectively. The experiments were carried out under the conditions of two modes of transportation with water and without water for 8 hour, respectively. The water temperature was controlled at (20.0±2.0) ℃ for transportation with water, while the temperature in the waterless styrofoam box was controlled at (15.0±3.0) ℃. The culture was temporarily maintained for 14 days after transportation. The breeding conditions and management methods were basically the same before and after transportation. The water temperature was (27.5±1.0) ℃, and the salinity was (31.5±0.5). Every day change 2/3 of the water and feed the mixed algae liquid of Isochrysis zhanjiangensis, Chaetoceros muelleri and Platymonas subcordiformis. The survival rates and growth parameters were estimated after 8 h transportation, 7 days and 14 days temporarily maintained, respectively. The P. penguin juveniles were sampled before transportation and used as control group, then juveniles were divided into two experimental groups for transportation with and without water respectively. The juveniles from different experimental groups were randomly sampled after transportation. Then, the juveniles were sampled on the 7th day and 14th day of the recovery period. The activity of amylase (AMS), superoxide dismutase (SOD), acid phosphatase (ACP), glutamic-oxalacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT), and the content of cortisol were used as biochemical indicators. The frozen soft tissues were dissected on the ice surface and homogenized on ice in 0.2 mol/L (w/v) ice-cold physiological saline, and the homogenates were centrifuged at 2 500 r/min for 10 min. Take the supernatant for enzyme activity determination, and repeat the determination 3 times for each sample. The results showed that the survival rates with water transport and waterless transport were (98.00±0.57)% and (97.00±1.00)%, respectively. On the 14th day of the recovery period, the survival rates with water transport and waterless transport reached (97.00±1.00)% and (82.00±0.71)%, respectively. Furthermore, after 14 days recovery, the shell length, shell height and body weight of P. penguin in water transport were significantly higher than those in waterless transport (P<0.05), while the content of cortisol level was (1 999.50±10.18) µg/L in the P. penguin transported with water, which was significantly higher than those transported without water [(1 668.46±20.36) µg/L]. The amylase activity after both transports increased, and on the 14th day of the recovery period, the amylase activity after transport with water increased to (1.56±0.08) U/mg prot, which was significantly higher than (1.06±0.04) U/mg prot with transport without water (P<0.05). The activities of GOT and GPT were increased in water transportation, while decreasing in waterless transportation. During the recovery stage, the ACP activity was decreased to (79.56±1.04) U/mg prot at 14th day in water transportation group, while increased to (168.24±3.46) U/mg prot in waterless transportation group. Furthermore, the GOT and GPT activities were trends to increase both in water and waterless transportation, while SOD activity was trend to decrease. The research results show that under certain conditions, water transport and waterless transport can significantly affect the growth, digestion and antioxidant properties of juveniles. Under these two transport modes, the water transport effect and the later physiological recovery are relatively better, with higher survival rate and better growth. After transportation, the body of the P. penguin needs a certain period of time to recover to a normal state, and then can be more adaptive to other adverse environmental factors.
At present, the research on the physiological effects of transportation activities on aquatic organisms mainly focuses on fish, crustaceans and echinoderms. There are lacking details for transportation effect on Pteria penguin. In order to explore the effects of transportation modes on the survival, growth, digestion and antioxidant properties of P. penguin juveniles, this study was carried out under the conditions of transportation with water and without water, respectively. The experiments were carried out under the conditions of two modes of transportation with water and without water for 8 hour, respectively. The water temperature was controlled at (20.0±2.0) ℃ for transportation with water, while the temperature in the waterless styrofoam box was controlled at (15.0±3.0) ℃. The culture was temporarily maintained for 14 days after transportation. The breeding conditions and management methods were basically the same before and after transportation. The water temperature was (27.5±1.0) ℃, and the salinity was (31.5±0.5). Every day change 2/3 of the water and feed the mixed algae liquid of Isochrysis zhanjiangensis, Chaetoceros muelleri and Platymonas subcordiformis. The survival rates and growth parameters were estimated after 8 h transportation, 7 days and 14 days temporarily maintained, respectively. The P. penguin juveniles were sampled before transportation and used as control group, then juveniles were divided into two experimental groups for transportation with and without water respectively. The juveniles from different experimental groups were randomly sampled after transportation. Then, the juveniles were sampled on the 7th day and 14th day of the recovery period. The activity of amylase (AMS), superoxide dismutase (SOD), acid phosphatase (ACP), glutamic-oxalacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT), and the content of cortisol were used as biochemical indicators. The frozen soft tissues were dissected on the ice surface and homogenized on ice in 0.2 mol/L (w/v) ice-cold physiological saline, and the homogenates were centrifuged at 2 500 r/min for 10 min. Take the supernatant for enzyme activity determination, and repeat the determination 3 times for each sample. The results showed that the survival rates with water transport and waterless transport were (98.00±0.57)% and (97.00±1.00)%, respectively. On the 14th day of the recovery period, the survival rates with water transport and waterless transport reached (97.00±1.00)% and (82.00±0.71)%, respectively. Furthermore, after 14 days recovery, the shell length, shell height and body weight of P. penguin in water transport were significantly higher than those in waterless transport (P<0.05), while the content of cortisol level was (1 999.50±10.18) µg/L in the P. penguin transported with water, which was significantly higher than those transported without water [(1 668.46±20.36) µg/L]. The amylase activity after both transports increased, and on the 14th day of the recovery period, the amylase activity after transport with water increased to (1.56±0.08) U/mg prot, which was significantly higher than (1.06±0.04) U/mg prot with transport without water (P<0.05). The activities of GOT and GPT were increased in water transportation, while decreasing in waterless transportation. During the recovery stage, the ACP activity was decreased to (79.56±1.04) U/mg prot at 14th day in water transportation group, while increased to (168.24±3.46) U/mg prot in waterless transportation group. Furthermore, the GOT and GPT activities were trends to increase both in water and waterless transportation, while SOD activity was trend to decrease. The research results show that under certain conditions, water transport and waterless transport can significantly affect the growth, digestion and antioxidant properties of juveniles. Under these two transport modes, the water transport effect and the later physiological recovery are relatively better, with higher survival rate and better growth. After transportation, the body of the P. penguin needs a certain period of time to recover to a normal state, and then can be more adaptive to other adverse environmental factors.
LI Xiaokang
,
WU Haiyan
,
CHENG Ling
,
CHE Hanyu
,
LIU Lijuan
,
MOU Haijin
,
TAN Zhijun
,
ZHENG Guanchao
2024, 45(4):195-204.
DOI: 10.19663/j.issn2095-9869.20230801001
Abstract:
Paralytic shellfish toxins (PSTs) are a class of acute neurotoxins with nearly 60 congeners. Shellfish that filter feed on toxin-producing algae exhibit PST accumulation in tissues, and the consumption of toxic shellfish poses a major threat to human health. China has the largest aquaculture industry in the world, with shellfish production of approximately 15.89 million tons in 2022 and many shellfish consumers. The PST poisoning incidents in China exhibit the characteristics of a wide distribution area, recurring regional risk, diverse toxin sources, and seasonal differences. PST consumption causes acute symptoms of poisoning and even death in many people, with a high lethality rate. This is a serious threat to the health of consumers and detrimental to the social stability of the region. In northern China, Hebei Province has rich fisheries resources, with a mariculture output of approximately 580,000 tons in 2022. In recent years, PSTs have been detected several times in bivalve shellfish inshore in Hebei Province, especially along the coast of Qinhuangdao. A serious shellfish poisoning episode was reported in Qinhuangdao in 2016, with PST concentrations exceeding the safety limit of 800 μgSTX equivalents/kg (μg STXeq/kg) by a factor of 65. The main algal species responsible for the poisoning was Alexandrium catenella. However, the current investigations of PST pollution in Hebei Province mainly focus on the shellfish species Mytilus galloprovincialis and Argopecten irradians in the sea area of Shanhaiguan, Qinhuangdao, and investigations on other coastal cities of Hebei Province and a wide range of different shellfish species are lacking. Moreover, few risk assessment studies have been conducted. A continuous PST survey was conducted in 2022 on six species of shellfish, namely M. galloprovincialis, Scapharca subcrenata, A. irradians, Scapharca broughtonii, Ruditapes philippinarum, and Crassostrea gigas, collected by netting in Tangshan and Qinhuangdao, and the residual status of PSTs was assessed for acute exposure using liquid chromatography-tandem mass spectrometry. The results showed that PSTs were detected in shellfish samples collected from March to June, with a detection rate of 100%. However, no values exceeded the European Union limit. Among the shellfish samples collected from March to June, those assessed in April had the highest average concentration, followed by those in May, March, and June, which had the lowest average concentration. The main components detected in shellfish samples from March to June were gonyautoxins (GTX) 1–4; the highest concentrations were detected in April. Highly toxic saxitoxin (STX) and decarbamoylneosaxitoxin (dcNEO) were detected from April to June and not in March. Decarbamoylgonyautoxin (dcGTX) 2 was not detected in March or April; however, it was detected in May and June. The sea area near Qinhuangdao was more polluted than that near Tangshan. Among the collected shellfish samples, significant differences were observed in the average concentration of PSTs in shellfish samples of different species, and the concentration ranged from highest to lowest in species as follows: M. galloprovincialis > S. subcrenata > A. irradians > S. broughtonii > R. philippinarum > C. gigas. Large differences were observed between the six shellfish species regarding the accumulation of 11 PST components, among which GTX1–4 and carbamatetoxin (C) 1 and 2 were the most commonly detected components. The highest concentrations of GTX1 and 4 were observed in M. galloprovincialis, the highest concentrations of GTX2 and 3 were observed in S. subcrenata, and the highest concentrations of C1 and 2 were observed in A. irradians. A low detection rate was recorded for highly toxic STX and neosaxitoxin (NEO in samples, except in M. galloprovincialis and S. subcrenata, in which all 11 PSTs were detected. In the other four shellfish species, only certain of the components were detected. Statistical analysis of the highest levels of PSTs in nearshore shellfish in Hebei Province in recent years showed a decreasing trend. Acute exposure assessments using the maximum value of PSTs showed that none of the six shellfish species exceeded the acute reference dose values recommended by the Food and Agriculture Organization of the United Nations/World Health Organization and European Food Safety Authority, suggesting that toxin levels were safe and acceptable. M. galloprovincialis had the highest dietary exposure risk, as a few residues were present, and symptoms of PST poisoning, such as dizziness and nausea, may occur after ingesting large quantities of M. galloprovincialis. Increased attention should be paid to shellfish with high dietary exposure assessment values, such as M. galloprovincialis and S. subcrenata. In this study, we investigated PSTs in shellfish from Hebei coastal waters and observed that PSTs were detected in shellfish samples from March to June, with the highest average concentration in April, followed by May and March, with the lowest average concentration in June. In addition, the main components detected in shellfish samples were GTX1–4. The analysis of different shellfish species showed that M. galloprovincialis had the highest average PST concentration, followed by S. subcrenata, A. irradians, S. broughtonii, R. philippinarum, and C. gigas; GTX1–4 and C1 and 2 were detected in all six shellfish species. Dietary exposure assessment for consumers in Hebei Province showed that the toxin levels were safe and acceptable. However, follow-up surveys and studies are necessary due to the paucity of surveys for different cities and species on the coast of Hebei.
Paralytic shellfish toxins (PSTs) are a class of acute neurotoxins with nearly 60 congeners. Shellfish that filter feed on toxin-producing algae exhibit PST accumulation in tissues, and the consumption of toxic shellfish poses a major threat to human health. China has the largest aquaculture industry in the world, with shellfish production of approximately 15.89 million tons in 2022 and many shellfish consumers. The PST poisoning incidents in China exhibit the characteristics of a wide distribution area, recurring regional risk, diverse toxin sources, and seasonal differences. PST consumption causes acute symptoms of poisoning and even death in many people, with a high lethality rate. This is a serious threat to the health of consumers and detrimental to the social stability of the region. In northern China, Hebei Province has rich fisheries resources, with a mariculture output of approximately 580,000 tons in 2022. In recent years, PSTs have been detected several times in bivalve shellfish inshore in Hebei Province, especially along the coast of Qinhuangdao. A serious shellfish poisoning episode was reported in Qinhuangdao in 2016, with PST concentrations exceeding the safety limit of 800 μgSTX equivalents/kg (μg STXeq/kg) by a factor of 65. The main algal species responsible for the poisoning was Alexandrium catenella. However, the current investigations of PST pollution in Hebei Province mainly focus on the shellfish species Mytilus galloprovincialis and Argopecten irradians in the sea area of Shanhaiguan, Qinhuangdao, and investigations on other coastal cities of Hebei Province and a wide range of different shellfish species are lacking. Moreover, few risk assessment studies have been conducted. A continuous PST survey was conducted in 2022 on six species of shellfish, namely M. galloprovincialis, Scapharca subcrenata, A. irradians, Scapharca broughtonii, Ruditapes philippinarum, and Crassostrea gigas, collected by netting in Tangshan and Qinhuangdao, and the residual status of PSTs was assessed for acute exposure using liquid chromatography-tandem mass spectrometry. The results showed that PSTs were detected in shellfish samples collected from March to June, with a detection rate of 100%. However, no values exceeded the European Union limit. Among the shellfish samples collected from March to June, those assessed in April had the highest average concentration, followed by those in May, March, and June, which had the lowest average concentration. The main components detected in shellfish samples from March to June were gonyautoxins (GTX) 1–4; the highest concentrations were detected in April. Highly toxic saxitoxin (STX) and decarbamoylneosaxitoxin (dcNEO) were detected from April to June and not in March. Decarbamoylgonyautoxin (dcGTX) 2 was not detected in March or April; however, it was detected in May and June. The sea area near Qinhuangdao was more polluted than that near Tangshan. Among the collected shellfish samples, significant differences were observed in the average concentration of PSTs in shellfish samples of different species, and the concentration ranged from highest to lowest in species as follows: M. galloprovincialis > S. subcrenata > A. irradians > S. broughtonii > R. philippinarum > C. gigas. Large differences were observed between the six shellfish species regarding the accumulation of 11 PST components, among which GTX1–4 and carbamatetoxin (C) 1 and 2 were the most commonly detected components. The highest concentrations of GTX1 and 4 were observed in M. galloprovincialis, the highest concentrations of GTX2 and 3 were observed in S. subcrenata, and the highest concentrations of C1 and 2 were observed in A. irradians. A low detection rate was recorded for highly toxic STX and neosaxitoxin (NEO in samples, except in M. galloprovincialis and S. subcrenata, in which all 11 PSTs were detected. In the other four shellfish species, only certain of the components were detected. Statistical analysis of the highest levels of PSTs in nearshore shellfish in Hebei Province in recent years showed a decreasing trend. Acute exposure assessments using the maximum value of PSTs showed that none of the six shellfish species exceeded the acute reference dose values recommended by the Food and Agriculture Organization of the United Nations/World Health Organization and European Food Safety Authority, suggesting that toxin levels were safe and acceptable. M. galloprovincialis had the highest dietary exposure risk, as a few residues were present, and symptoms of PST poisoning, such as dizziness and nausea, may occur after ingesting large quantities of M. galloprovincialis. Increased attention should be paid to shellfish with high dietary exposure assessment values, such as M. galloprovincialis and S. subcrenata. In this study, we investigated PSTs in shellfish from Hebei coastal waters and observed that PSTs were detected in shellfish samples from March to June, with the highest average concentration in April, followed by May and March, with the lowest average concentration in June. In addition, the main components detected in shellfish samples were GTX1–4. The analysis of different shellfish species showed that M. galloprovincialis had the highest average PST concentration, followed by S. subcrenata, A. irradians, S. broughtonii, R. philippinarum, and C. gigas; GTX1–4 and C1 and 2 were detected in all six shellfish species. Dietary exposure assessment for consumers in Hebei Province showed that the toxin levels were safe and acceptable. However, follow-up surveys and studies are necessary due to the paucity of surveys for different cities and species on the coast of Hebei.
2025, 46(5):69-84.
DOI: 10.19663/j.issn2095-9869.20241119003
Abstract:
Population aging has become a universal phenomenon with the rapid development of the global economy and medical technology. China, which has the largest number of older adult people, has one of the highest aging rates in the world. Despite the large elderly population, the market lacks food designed to meet their safety and nutritional needs. Therefore, food development for older adults has become a popular research topic. In 2018, the National Health Commission of China released the “National Food Safety Standard–General Rules for Elderly Food” (draft for soliciting opinions), aiming to regulate food production and quality standards for older adults. It classifies food for older adults into easily consumable, nutritional-formula, and nutritional-supplement foods and sets specific nutritional requirements for them. Experts have proposed principles for developing food for older adults, including providing sufficient high-quality protein, dietary fiber, vitamins, and trace elements, while emphasizing low-fat, low-sugar, low-calorie, and low-cholesterol formula designs. Additionally, texture, sensory properties, and packaging suitability during food processing are considered to meet the physiological and psychological needs of older adults. Compared with the international market, the food market for older individuals in China is still in its infancy and sells mainly health products. The variety of foods suitable for older adults is relatively limited and includes milk powder, pastries, and biscuits. Although these foods are easy to chew and swallow, they often lack sufficient nutritional value and do not fully meet the nutritional needs of the elderly population. Research has shown that vitamin and folic acid content in domestic pre-packaged food for older individuals is insufficient, and the carbohydrate and energy content is often high, increasing the risk of obesity and cardiovascular and cerebrovascular diseases in older individuals with a low metabolic rate. Leveraging the high economic and nutritional value, as well as the delicious taste of seabass (Lateolabrax japonicus), its meat serves as an excellent source of high-quality protein with a low fat content, soft texture, and easy chewability, making it an ideal ingredient in food designed for older adults. Based on the dietary needs of older adults, this study developed an easily chewable and digestible seabass paste by adding carrot powder, celery powder, and inulin. Single-factor experiments and response surface methodology were used to determine the optimal ratios of the three nutrient powders, using hardness and sensory scores as key evaluation criteria. Textural characteristics and nutritional indicators of the products were also analyzed. The study also assessed the effect of different packaging methods (regular packaging and vacuum packaging) and refrigeration temperatures (4 ℃ and –2 ℃) on the quality of the sea bass product. Quality indicators included textural characteristics, sensory aspects, volatile basic nitrogen content (TVB-N), thiobarbituric acid value (TBA), and total colony count. The optimal amounts of nutrients for sea bass paste were 1.15% carrot powder, 1.10% celery powder, and 1.00% inulin. The paste contained 15.24 g protein and 5.73 g fat per 100 g. The amino acid profile aligned with the ideal protein pattern recommended by the Food and Agriculture Organization/World Health Organization. Moreover, the sea bass paste contained 18 types of fatty acids, with the relative unsaturated fatty acid content reaching 72.1% and the total EPA and DHA content accounting for 11.12%. The sea bass paste contained the highest amount of vitamin E (3.54 mg/100 g), followed by niacin (3.48 mg/100 g). It exhibits moderate texture, good water retention, and is easily chewable, making it suitable for consumption by older adults. During the first 20 days of storage, the hardness of sea bass paste gradually increased, but there was no significant difference between the two refrigeration temperature groups (4 and –2 ℃). However, the hardness of the vacuum-packed sea bass products continued to increase for up to 30 days of storage, but it decreased sharply in the regularly packaged product. Storage experiments demonstrated that vacuum packaging could effectively delay the increase in the TVB-N, TBA value, and total colony count, maintaining the quality of the sea bass paste. The TVB-N of the regularly packaged product was close to the 30 mg/100 g limit after 30 days, whereas vacuum-packed sea bass paste stored at –2 °C was still below 13 mg/100 g (within the range of Class Ⅰ products). Fat oxidation was higher in the regularly packaged fish paste than in the vacuum-packed group. This indicates that vacuum packing was effective in slowing down the fat-oxidation process. Vacuum-packed sea bass paste can be stored for 7 days at 4 ℃ and 15 days at –2 ℃, showing a significantly superior preservation effect compared to regular packaging. In conclusion, this study not only introduces a nutritious and healthy food option for older adults but also presents novel insights into the processing and high-value utilization of sea bass, offering technical support and a reference for the diversification and development of marine fish products.
Population aging has become a universal phenomenon with the rapid development of the global economy and medical technology. China, which has the largest number of older adult people, has one of the highest aging rates in the world. Despite the large elderly population, the market lacks food designed to meet their safety and nutritional needs. Therefore, food development for older adults has become a popular research topic. In 2018, the National Health Commission of China released the “National Food Safety Standard–General Rules for Elderly Food” (draft for soliciting opinions), aiming to regulate food production and quality standards for older adults. It classifies food for older adults into easily consumable, nutritional-formula, and nutritional-supplement foods and sets specific nutritional requirements for them. Experts have proposed principles for developing food for older adults, including providing sufficient high-quality protein, dietary fiber, vitamins, and trace elements, while emphasizing low-fat, low-sugar, low-calorie, and low-cholesterol formula designs. Additionally, texture, sensory properties, and packaging suitability during food processing are considered to meet the physiological and psychological needs of older adults. Compared with the international market, the food market for older individuals in China is still in its infancy and sells mainly health products. The variety of foods suitable for older adults is relatively limited and includes milk powder, pastries, and biscuits. Although these foods are easy to chew and swallow, they often lack sufficient nutritional value and do not fully meet the nutritional needs of the elderly population. Research has shown that vitamin and folic acid content in domestic pre-packaged food for older individuals is insufficient, and the carbohydrate and energy content is often high, increasing the risk of obesity and cardiovascular and cerebrovascular diseases in older individuals with a low metabolic rate. Leveraging the high economic and nutritional value, as well as the delicious taste of seabass (Lateolabrax japonicus), its meat serves as an excellent source of high-quality protein with a low fat content, soft texture, and easy chewability, making it an ideal ingredient in food designed for older adults. Based on the dietary needs of older adults, this study developed an easily chewable and digestible seabass paste by adding carrot powder, celery powder, and inulin. Single-factor experiments and response surface methodology were used to determine the optimal ratios of the three nutrient powders, using hardness and sensory scores as key evaluation criteria. Textural characteristics and nutritional indicators of the products were also analyzed. The study also assessed the effect of different packaging methods (regular packaging and vacuum packaging) and refrigeration temperatures (4 ℃ and –2 ℃) on the quality of the sea bass product. Quality indicators included textural characteristics, sensory aspects, volatile basic nitrogen content (TVB-N), thiobarbituric acid value (TBA), and total colony count. The optimal amounts of nutrients for sea bass paste were 1.15% carrot powder, 1.10% celery powder, and 1.00% inulin. The paste contained 15.24 g protein and 5.73 g fat per 100 g. The amino acid profile aligned with the ideal protein pattern recommended by the Food and Agriculture Organization/World Health Organization. Moreover, the sea bass paste contained 18 types of fatty acids, with the relative unsaturated fatty acid content reaching 72.1% and the total EPA and DHA content accounting for 11.12%. The sea bass paste contained the highest amount of vitamin E (3.54 mg/100 g), followed by niacin (3.48 mg/100 g). It exhibits moderate texture, good water retention, and is easily chewable, making it suitable for consumption by older adults. During the first 20 days of storage, the hardness of sea bass paste gradually increased, but there was no significant difference between the two refrigeration temperature groups (4 and –2 ℃). However, the hardness of the vacuum-packed sea bass products continued to increase for up to 30 days of storage, but it decreased sharply in the regularly packaged product. Storage experiments demonstrated that vacuum packaging could effectively delay the increase in the TVB-N, TBA value, and total colony count, maintaining the quality of the sea bass paste. The TVB-N of the regularly packaged product was close to the 30 mg/100 g limit after 30 days, whereas vacuum-packed sea bass paste stored at –2 °C was still below 13 mg/100 g (within the range of Class Ⅰ products). Fat oxidation was higher in the regularly packaged fish paste than in the vacuum-packed group. This indicates that vacuum packing was effective in slowing down the fat-oxidation process. Vacuum-packed sea bass paste can be stored for 7 days at 4 ℃ and 15 days at –2 ℃, showing a significantly superior preservation effect compared to regular packaging. In conclusion, this study not only introduces a nutritious and healthy food option for older adults but also presents novel insights into the processing and high-value utilization of sea bass, offering technical support and a reference for the diversification and development of marine fish products.
2025, 46(5):244-254.
DOI: 10.19663/j.issn2095-9869.20241021001
Abstract:
Alzheimer's disease (AD) is a neurodegenerative disease characterized primarily by progressive memory decline, cognitive impairment, and disturbances in language and psychomotor functions. With the aging of the global population and the deterioration of the living environment, the number of patients is also increasing. The World Alzheimer's Disease Report estimates that the global population of Alzheimer's patients is expected to increase to 115 million by 2050, which could notably affect the world economy and society. The cholinergic hypothesis is a widely accepted theory describing AD pathology, which considers acetylcholine to be an important neurotransmitter involved in learning and memory. The lack of acetylcholine results in insufficient cholinergic signal transmission, consequently contributing to the development of AD. Acetylcholinesterase (AChE) inhibitors can reduce the decomposition of acetylcholine by inhibiting the activity of AChE, making them one of the primary drugs for the treatment of AD. The AChE inhibitor drugs approved by the FDA include donepezil and galantamine. However, the micro-molecule drugs have strong side effects; therefore, finding new safe and efficient AChE inhibitors is necessary. Pathological protein aggregation, oxidative stress, and metal ion homeostasis imbalance exacerbate disease progression. The correlation between different pathogenic factors has shifted drug research from single to multiple targets. Bioactive peptides are peptide compounds with biological activity, which have the advantages of high selectivity, high specificity, multi-target, high safety, and low immunogenicity. In particular, bioactive peptides from marine sources have many specific structures and functions owing to their unique growth environment. Researchers have prepared and isolated peptides from marine organisms with antioxidants, anti-inflammatory, high blood pressure, uric acid, immune regulation, and other effects. Trachinotus ovatus has the advantages of high yield, fast growth, strong disease resistance, high nutritional value, high protein and essential amino acid content, and is a good raw material for preparing bioactive peptides. Enzymatic hydrolysis is the most commonly used method for preparing peptides owing to its mildness, controllability and low cost. In this study, the AChE inhibitory peptide was prepared by enzymolysis of T. ovatus. Enzymolysis was performed under five proteases (neutral protease, papain, alkaline protease, protamines, and trypsin), and different enzymolysis times (1, 2, 4, 6, and 8 h), and the optimal enzymolysis time were screened based on AChE inhibition activity and antioxidant capacity. The hydrolysis degree, molecular weight distribution, amino acid composition and chelating ability of metal ions were determined, and the structure of the products was determined by ultraviolet and Fourier transform infrared. The results showed that the 4 h hydrolysate of papain had the highest AChE inhibition rate (18.02±0.78)%, which was significantly higher than other protease and positive control cerebrolin (P＜0.05). The ABTS radical scavenging rate of the enzymolysis product was (52.54±0.89)%, the degree of hydrolysis was 14.86%, and the proportion of components with molecular weight ＜3 kDa was 96.87%. Correlation analysis showed that AChE inhibition activity was significantly positively correlated with these three indices (P＜0.05). In addition, the amino acids with the highest content in the 4 h papain hydrolysate were glutamic acid, aspartic acid, and lysine, all of which were positively or negatively charged. The proportion of hydrophobic amino acids was 34.92%, which contributed to the interaction between the hydrolysate products and AChE and free radicals, improving the inhibition rate of AChE and antioxidant activity. The binding ability of metal ions was determined. The enzymatic hydrolysis product could bind Ca2+ and Fe2+; the binding rates were (26.28±1.20)% and (14.25±0.85)%, respectively, and the AChE inhibition activity was improved after binding. Ultraviolet analysis showed that the hydrolysates interacted with calcium and iron to form new compounds. Fourier transform infrared spectroscopy showed that amino and carboxyl groups participated in the formation of the complexes. Consequently, the screened hydrolysate has good potential for treating AD. In the future, the AChE inhibition effect of AChE inhibitory peptide in vivo will be further verified, and the primary role of peptide composition will be explored, including the mechanism of action. This provides theoretical support and scientific basis for marine bioactive peptides in the improvement and treatment of AD disease.
Alzheimer's disease (AD) is a neurodegenerative disease characterized primarily by progressive memory decline, cognitive impairment, and disturbances in language and psychomotor functions. With the aging of the global population and the deterioration of the living environment, the number of patients is also increasing. The World Alzheimer's Disease Report estimates that the global population of Alzheimer's patients is expected to increase to 115 million by 2050, which could notably affect the world economy and society. The cholinergic hypothesis is a widely accepted theory describing AD pathology, which considers acetylcholine to be an important neurotransmitter involved in learning and memory. The lack of acetylcholine results in insufficient cholinergic signal transmission, consequently contributing to the development of AD. Acetylcholinesterase (AChE) inhibitors can reduce the decomposition of acetylcholine by inhibiting the activity of AChE, making them one of the primary drugs for the treatment of AD. The AChE inhibitor drugs approved by the FDA include donepezil and galantamine. However, the micro-molecule drugs have strong side effects; therefore, finding new safe and efficient AChE inhibitors is necessary. Pathological protein aggregation, oxidative stress, and metal ion homeostasis imbalance exacerbate disease progression. The correlation between different pathogenic factors has shifted drug research from single to multiple targets. Bioactive peptides are peptide compounds with biological activity, which have the advantages of high selectivity, high specificity, multi-target, high safety, and low immunogenicity. In particular, bioactive peptides from marine sources have many specific structures and functions owing to their unique growth environment. Researchers have prepared and isolated peptides from marine organisms with antioxidants, anti-inflammatory, high blood pressure, uric acid, immune regulation, and other effects. Trachinotus ovatus has the advantages of high yield, fast growth, strong disease resistance, high nutritional value, high protein and essential amino acid content, and is a good raw material for preparing bioactive peptides. Enzymatic hydrolysis is the most commonly used method for preparing peptides owing to its mildness, controllability and low cost. In this study, the AChE inhibitory peptide was prepared by enzymolysis of T. ovatus. Enzymolysis was performed under five proteases (neutral protease, papain, alkaline protease, protamines, and trypsin), and different enzymolysis times (1, 2, 4, 6, and 8 h), and the optimal enzymolysis time were screened based on AChE inhibition activity and antioxidant capacity. The hydrolysis degree, molecular weight distribution, amino acid composition and chelating ability of metal ions were determined, and the structure of the products was determined by ultraviolet and Fourier transform infrared. The results showed that the 4 h hydrolysate of papain had the highest AChE inhibition rate (18.02±0.78)%, which was significantly higher than other protease and positive control cerebrolin (P＜0.05). The ABTS radical scavenging rate of the enzymolysis product was (52.54±0.89)%, the degree of hydrolysis was 14.86%, and the proportion of components with molecular weight ＜3 kDa was 96.87%. Correlation analysis showed that AChE inhibition activity was significantly positively correlated with these three indices (P＜0.05). In addition, the amino acids with the highest content in the 4 h papain hydrolysate were glutamic acid, aspartic acid, and lysine, all of which were positively or negatively charged. The proportion of hydrophobic amino acids was 34.92%, which contributed to the interaction between the hydrolysate products and AChE and free radicals, improving the inhibition rate of AChE and antioxidant activity. The binding ability of metal ions was determined. The enzymatic hydrolysis product could bind Ca2+ and Fe2+; the binding rates were (26.28±1.20)% and (14.25±0.85)%, respectively, and the AChE inhibition activity was improved after binding. Ultraviolet analysis showed that the hydrolysates interacted with calcium and iron to form new compounds. Fourier transform infrared spectroscopy showed that amino and carboxyl groups participated in the formation of the complexes. Consequently, the screened hydrolysate has good potential for treating AD. In the future, the AChE inhibition effect of AChE inhibitory peptide in vivo will be further verified, and the primary role of peptide composition will be explored, including the mechanism of action. This provides theoretical support and scientific basis for marine bioactive peptides in the improvement and treatment of AD disease.
2023, 44(1):181-190.
DOI: 10.19663/j.issn2095-9869.20210816001
Abstract:
Paralytic shellfish toxins (PSTs) are phycotoxins widely distributed worldwide and pose serious marine ecosystems and human health threats. In China's Yellow Sea and the Bohai Sea, Alexandrium spp. has been certified as the major causative dinoflagellate of PSTs, especially in Qinhuangdao, Hebei Province where several poisoning events have been reported, with tens of consumers suffering and some even dying. In terms of these events, mussels contaminated with PSTs were the major cause of consumer poisoning. Therefore, it is vital to reveal the risk of PSTs in these shellfish, which requires scientific opinions on the formation of terminal components of PSTs in mussels. Generally, mussels are not sensitive to PSTs, resulting in the high accumulation of PSTs in their tissues. The PSTs distribute, bio-transfer, and metabolism, and the terminal metabolites pose a risk to consumers. From 2016 to the present, several serious events have occurred in Qinhuangdao caused by PSTs contamination in mussels, which resulted in poisoning by tens of consumers and a huge loss of regional economy. This study exposed purple mussel Mytilus galloprovincialis, the key cultured species of bivalves in Qinhuangdao, to Alexandrium catenella (GY-H25), the predominant producer of PSTs in this area. The accumulation and biotransformation process of PSTs in visceral mass and edible tissue and the accumulation metabolism kinetics were analyzed under exposure to different cell densities by liquid chromatography-tandem mass spectrometry. Our results showed that the growth and toxin production of GY-H25 was stable. The main components of PSTs were N-sulfocarbamoylgonyautoxin (C1 and C2), with the highest algal cell density of 3.5×107 cells/L and the highest production capacity of 2.96 pg STXeq/cell. Toxin-producing algae with the highest production of PSTs per unit volume and algal cell density (22 days) were selected for the exposure experiment. After exposure, the mussel accumulated a high content of PSTs in both visceral mass and edible tissue, with a similar trend in both exposure densities. The whole exposure experiment could be divided into four periods: 0~2 days as the initial exposure period (period Ⅰ); 2~7 days as the period of rapid accumulation (period Ⅱ); 7~12 days as the period of rapid metabolism (period Ⅲ); 12~30 days as the stable period (period Ⅳ). However, the level of PSTs in the visceral mass of mussels in both exposure groups exceeded the maximum residue limit (MRL) of EU (800 μg STX EQ/kg) at the end of the experiment, while that of PSTs in edible flesh was below the MRL. Comparatively, the highest concentration of PSTs in the visceral mass reached 6815.36 μg/kg in the high exposure group, which was 2.61 times that of the low exposure group, with an average accumulation rate of 17.89%, which was significantly higher than that of the low exposure group (13.06%). The results showed that the accumulation of PSTs in the visceral mass and edible tissue of Mytilus galloprovincialis was harmful to its tissues and organs. The toxin excretion rates of the high-and low-concentration groups of PSTs were 74.39 % and 59.15 %, respectively, after 23 days. The average daily elimination rate was 14.4 %, the metabolism rate of Mytilus edulis slowed down in the stable period (period Ⅳ), and some toxins remained in the visceral mass after 23 days of metabolism, which easily formed long-term toxin retention and threatened human life safety. In addition, PSTs in Mytilus galloprovincialis showed a strong biotransformation ability, mainly occurring among C1, C2, and GTX5. According to this research, the transformation pathway from C2 to GTX5 was the main pathway for GTX5 formation during rapid metabolism and stable periods. At the same time, the transformation of C1 to GTX5 was higher than that of C2 to C1, leading to a reduction in the overall proportion of C1. According to the comprehensive evaluation of the metabolic products and toxic equivalence factor (TEF) of GST components in mussels, the metabolic transformation of PSTs in mussels will further promote the formation and proportion of highly toxic GTX5, which will increase the terminal toxicity of PSTs in mussels and may also pose a higher risk to consumers. In this study, compared with the natural conditions, the concentration of toxic algae was far below the harmful algal bloom exposure. The total accumulation of toxins was far lower than the total accumulation of toxins in mussels exposed to harmful algal blooms. Even so, the total amount of residual toxins in the mussel viscera of the high concentration group was still enough to threaten human life safety at the end of the experiment. It was found that the toxin content in the visceral tissue tended to be stable over 12 to 30 days without an obvious downward trend. Even the toxin content increases due to the toxin transformation phenomenon, which means the difficulty in predicting the time required for PSTs in the visceral mass reduced to below the MRLs. Therefore, this study contributes to the scientific assessment of PSTs risk in mussels and provides a basis for establishing regional PSTs monitoring programs.
Paralytic shellfish toxins (PSTs) are phycotoxins widely distributed worldwide and pose serious marine ecosystems and human health threats. In China's Yellow Sea and the Bohai Sea, Alexandrium spp. has been certified as the major causative dinoflagellate of PSTs, especially in Qinhuangdao, Hebei Province where several poisoning events have been reported, with tens of consumers suffering and some even dying. In terms of these events, mussels contaminated with PSTs were the major cause of consumer poisoning. Therefore, it is vital to reveal the risk of PSTs in these shellfish, which requires scientific opinions on the formation of terminal components of PSTs in mussels. Generally, mussels are not sensitive to PSTs, resulting in the high accumulation of PSTs in their tissues. The PSTs distribute, bio-transfer, and metabolism, and the terminal metabolites pose a risk to consumers. From 2016 to the present, several serious events have occurred in Qinhuangdao caused by PSTs contamination in mussels, which resulted in poisoning by tens of consumers and a huge loss of regional economy. This study exposed purple mussel Mytilus galloprovincialis, the key cultured species of bivalves in Qinhuangdao, to Alexandrium catenella (GY-H25), the predominant producer of PSTs in this area. The accumulation and biotransformation process of PSTs in visceral mass and edible tissue and the accumulation metabolism kinetics were analyzed under exposure to different cell densities by liquid chromatography-tandem mass spectrometry. Our results showed that the growth and toxin production of GY-H25 was stable. The main components of PSTs were N-sulfocarbamoylgonyautoxin (C1 and C2), with the highest algal cell density of 3.5×107 cells/L and the highest production capacity of 2.96 pg STXeq/cell. Toxin-producing algae with the highest production of PSTs per unit volume and algal cell density (22 days) were selected for the exposure experiment. After exposure, the mussel accumulated a high content of PSTs in both visceral mass and edible tissue, with a similar trend in both exposure densities. The whole exposure experiment could be divided into four periods: 0~2 days as the initial exposure period (period Ⅰ); 2~7 days as the period of rapid accumulation (period Ⅱ); 7~12 days as the period of rapid metabolism (period Ⅲ); 12~30 days as the stable period (period Ⅳ). However, the level of PSTs in the visceral mass of mussels in both exposure groups exceeded the maximum residue limit (MRL) of EU (800 μg STX EQ/kg) at the end of the experiment, while that of PSTs in edible flesh was below the MRL. Comparatively, the highest concentration of PSTs in the visceral mass reached 6815.36 μg/kg in the high exposure group, which was 2.61 times that of the low exposure group, with an average accumulation rate of 17.89%, which was significantly higher than that of the low exposure group (13.06%). The results showed that the accumulation of PSTs in the visceral mass and edible tissue of Mytilus galloprovincialis was harmful to its tissues and organs. The toxin excretion rates of the high-and low-concentration groups of PSTs were 74.39 % and 59.15 %, respectively, after 23 days. The average daily elimination rate was 14.4 %, the metabolism rate of Mytilus edulis slowed down in the stable period (period Ⅳ), and some toxins remained in the visceral mass after 23 days of metabolism, which easily formed long-term toxin retention and threatened human life safety. In addition, PSTs in Mytilus galloprovincialis showed a strong biotransformation ability, mainly occurring among C1, C2, and GTX5. According to this research, the transformation pathway from C2 to GTX5 was the main pathway for GTX5 formation during rapid metabolism and stable periods. At the same time, the transformation of C1 to GTX5 was higher than that of C2 to C1, leading to a reduction in the overall proportion of C1. According to the comprehensive evaluation of the metabolic products and toxic equivalence factor (TEF) of GST components in mussels, the metabolic transformation of PSTs in mussels will further promote the formation and proportion of highly toxic GTX5, which will increase the terminal toxicity of PSTs in mussels and may also pose a higher risk to consumers. In this study, compared with the natural conditions, the concentration of toxic algae was far below the harmful algal bloom exposure. The total accumulation of toxins was far lower than the total accumulation of toxins in mussels exposed to harmful algal blooms. Even so, the total amount of residual toxins in the mussel viscera of the high concentration group was still enough to threaten human life safety at the end of the experiment. It was found that the toxin content in the visceral tissue tended to be stable over 12 to 30 days without an obvious downward trend. Even the toxin content increases due to the toxin transformation phenomenon, which means the difficulty in predicting the time required for PSTs in the visceral mass reduced to below the MRLs. Therefore, this study contributes to the scientific assessment of PSTs risk in mussels and provides a basis for establishing regional PSTs monitoring programs.
