Effects of Different Fermentation Processes on the Quality, Flavor, and Microbial Diversity of Seriola dumerili Fish Sauce

This study utilized Seriola dumerili processing byproducts, fermented with Exiguobacterium profundum, Staphylococcus gallinarum, Aspergillus oryzae, Zygosaccharomyces rouxii, and Lactobacillus plantarum subsp. Plantarum. It compared enzymatic hydrolysis (M), koji-making (Q), and compound fermentation (QM) on fish sauce quality, flavor, and microbial dynamics against commercial sauce. In the 30 days, Group M had the highest protein content (12.00 g/100 mL), but lower amino nitrogen and free amino acids; Group Q had the richest free amino acids (1639.81 mg/100 mL), medium amino nitrogen content, but less protein dissolution; Group QM had the highest amino nitrogen content (0.67 g/100 mL), lowest salt content (9.74 g/100 mL), protein content (11.16 g/100 mL), and free amino acid content (1576.08 mg/100 mL), which were also close to those of single fermentation process. Aldehydes, ketones, esters, alcohols, acids, phenols, pyrazines, pyridines, pyrroles, and other volatile flavor compounds were determined by GC-MS. The number of flavor compounds detected in each group was as follows: Q (145) > M (129) > QM (95) > commercial group (54) (p 1). 16S rRNA revealed Lacticaseibacillus paracasei, Lactiplantibacillus pentosus, Aspergillus flavus, and Zygosaccharomyces sp. NCYC 3042 as dominant microbes. Streptococcus sp. uncultured, Zygosaccharomyces sp. NCYC 3042, Fusarium oxysporum, and Zygosaccharomyces sp. NBRC 0495 showed positive correlations with most characteristic volatile flavor compounds (R > 0.65). Lacticaseibacillus paracasei, Streptococcus sp. uncultured, Zygosaccharomyces sp. NCYC 3042, and Zygosaccharomyces sp. NBRC 0495 have significant positive correlations with most organic acids (R > 0.69). QM fish sauce demonstrated superior quality and unique flavor compared to commercial sauce.