Controlled moromi fermentation of Antarctic krill (Euphausia superba): a scalable framework for fish sauce production from protein-rich marine resources

Moromi-type controlled fermentation offers a reproducible approach for producing fermented seasonings; however, its applicability to high-protein marine substrates remains insufficiently explored. This study investigated the feasibility and scalability of controlled moromi fermentation for producing fish sauce from Antarctic krill (Euphausia superba), a protein-rich marine biomass characterized by high lipid content, minimal carbohydrates, and strong endogenous proteolytic activity. To establish a reproducible fermentation system, endogenous enzymes were inactivated by boiling for 20 min, and fermentation was conducted using starter microorganisms koji mold (Aspergillus sojae), lactic acid bacteria (Tetragenococcus halophilus), and yeast (Zygosaccharomyces rouxii) and enzymatic activity derived from koji under controlled salt concentrations (12–18% (w/w) NaCl) and temperatures (10–30°C).

Salt concentration and fermentation temperature significantly influenced microbial dynamics, enzymatic activity, and chemical composition. Correlation analyses revealed that fermentation temperature predominantly governed protease activity and microbial succession, whereas salt concentration modulated microbial activity and metabolic balance, thereby affecting nitrogen accumulation and alcohol production. Moderate salt conditions (12–15% (w/w) NaCl) and elevated temperatures (20–30°C) enhanced proteolysis and amino acid formation, resulting in increased levels of taste-active compounds. Taste activity value (TAV) analysis demonstrated that glutamic acid and aspartic acid were dominant contributors to umami perception, while other amino acids contributed to sweetness and moderate bitterness.

Sensory evaluation indicated that the krill fish sauce exhibited strong umami, reduced fishy odor, and favorable aroma characteristics compared with commercial Southeast Asian fish sauces. Validation at the 2000-kg scale confirmed the robustness and reproducibility of the controlled fermentation system under industrial conditions. These findings demonstrate that moromi-type controlled fermentation provides a scalable and mechanistically grounded strategy for valorizing underutilized marine resources and producing high-quality fermented seasonings from Antarctic krill.