Abstract:To better understand the quality characteristics of traditional dried salted Spanish mackerel, the dried salted Spanish mackerel product with the best organoleptic qualities among seven commercial products was chosen, and then its basic physical and chemical characteristics were analyzed, including its salt content, nitrite content, total volatile basic nitrogen (T-VBN) content, thiobarbituric acid reactive substances (TBARS) value, and so on. Furthermore, the dominant strains of bacteria, which have important impacts on the fermentation process and flavor formation, were isolated, purified, and identified from the dried salted Spanish mackerel product. The physiological and biochemical characteristics of these dominant bacterial strains were also studied in detail. The results showed that the water content of the traditional dried salted Spanish mackerel was 54.40%, and the salt content was 3.1%，which means that the analyzed product can be classified as a semi-dry and low-salt product. The nitrite content was 5.07 mg/kg, so the sample met relevant food safety standards. The TVB-N content of the dried salted fish product was 40.12 mg/100 g, which exceeds the TVB-N content limit of common fresh and frozen marine fish (30.00 mg/100 g), so these results indicated that the degree of protein degradation during fermentation was significant. The TBARS value was 10.00 mg/kg, which is slightly higher than the recommended standard (8.00 mg/kg); however, the degree of lipid oxidation in the sample was within the range of sensory acceptability because of its low moisture content. In addition, according to the results of plate counts of bacterial colonies, bacteria were inferred to be the dominant microorganisms in the traditional dried salted Spanish mackerel rather than yeasts or molds. On the basis of analyses of 16S rDNA sequences, the dominant strains of bacteria in the product were identified as Lactobacillus sakei, Enterobacter aerogenes, Lysinibacillus macroides, and Enterobacter xiangfangensis. Among these, Lactobacillus sakei was further identified as possessing the typical characteristics of a fermentative species, and thus probably plays a major role in the fermentation of dried salted Spanish mackerel.
