暗纹东方鲀冻藏品质劣化的原因解析

Reasons for Quality Deterioration of Obscure Pufferfish Fillets During Frozen Storage

中文关键词: 暗纹东方鲀  冻藏  品质劣化  冰晶  内源蛋白酶  氧化

英文关键词: Obscure pufferfish  Frozen storage  Quality deterioration  Ice crystals  Endogenous proteases  Oxidation

中文摘要:

      通过比较冰晶、内源蛋白酶以及氧化对冻藏暗纹东方鲀(Takifugu obscurus)品质的影响，确定冻藏暗纹东方鲀品质劣化的关键因素。实验通过液氮浸渍快速冻结抑制鱼肉组织中冰晶增长、碘乙酸浸泡前处理抑制鱼肉内源蛋白酶活性、复合抗氧化剂浸泡前处理抑制蛋白/脂质氧化作用的设计，区分冰晶、内源蛋白酶和氧化3种因素对冻藏鱼肉品质的影响；并以硬度、解冻流失率、蒸煮损失率、挥发性盐基氮含量、K值、Ca2+-ATPase活性、肌原纤维小片化指数和肌纤维长度作为鱼肉品质的评价指标。结果显示，冻结过程中控制冰晶增长对暗纹东方鲀冻藏品质的改善作用最大，冻藏24周后，速冻组的硬度比内源蛋白酶抑制组和氧化抑制组分别提高了26.8%和20.5%，解冻流失率分别降低了44.2%和44.8%，且该处理组TVB-N、K值和Ca2+-ATPase活性变化更慢，24周后分别为10.5 mg/100 g、6.8%和1.43 μmol Pi/mg/10 min。综合各项指标发现，冰晶、内源蛋白酶和氧化对冻藏暗纹东方鲀品质劣化均有影响；其中，冰晶作用是导致暗纹东方鲀在冻藏过程中品质下降的最主要影响因素，内源蛋白酶和氧化对冻藏暗纹东方鲀品质的影响次之，且二者对品质影响无显著性差异。

英文摘要:

      This investigation aimed to compare the effects of ice crystals, endogenous proteases, and oxidation on the quality of obscure pufferfish (Takifugu obscurus) fillets during frozen storage, and detemine the dominant factors impacting their quality deterioration. The fillets were immersed in 1) liquid nitrogen, 2) iodoacetic acid solution, or 3) antioxidant mixtures (tea polyphenol and ascorbic acid solution), designed to inhibit the formation and growth of large ice crystals, activities of endogenous proteases, and the oxidization of proteins and lipids during storage, respectively. Therefore, the roles of these three factors in changing the quality of the frozen pufferfish fillets were differentiated. The hardness, thawing loss, cooking loss, total volatile basic nitrogen (TVB-N), K value, activity of Ca2+-ATPase, myofibril fragmentation index (MFI), and myofibril lengths were evaluated as quality indicators. The results showed that controlling the growth of ice crystals on the frozen pufferfish fillets had the greatest impacts on quality. After 24 weeks, the hardness of frozen pufferfish fillets with smaller ice crystals was about 26.8 % and 20.5 %, higher than that with the inhibition of endogenous proteolytic activities and oxidation, respectively. When it came to the thawing loss, it was about 44.2% and 44.8% lower with quick-freezing than in the other two groups. In addition, the TVB-N, K value, and activity of Ca2+- ATPase with the treatment of liquid nitrogen before freezing changed more slowly. In this group, the values of the quality indicators were 10.5 mg/100 g, 6.8 %, and 1.43 μmol Pi/mg/10 min after 24 weeks, respectively. As a result, ice crystals, endogenous proteases and oxidation have all contributed to the deterioration of frozen pufferfish fillets. Among them, the formation of ice crystals was the dominant factor for quality loss in frozen pufferfish fillets and the effects from the endogenous proteases and oxidation on the quality of pufferfish fillets followed, and there was no significant differences between these two factors.