The Influence of Douchi Starter Cultures on the Composition of Extractive Components, Microbiological Activity, and Sensory Properties of Fermented Fish Pastes

Three experiments were conducted to test the hypothesis that douchi cultures could serve as a potential starter for enhancing the quality attributes of fermented silver carp meat. In experiment 1, an active, prefermented douchi culture was incorporated into a fish paste to aid in the fish fermentation (30 d) and facilitate biochemical production of extractive flavor components (PRF). In experiment 2, a fully fermented (30 d) douchi was added to a fish paste and the mixture was fermented for 30 d (PSF). In experiment 3, a fish paste without the douchi culture was fermented for 30 d (CF). Total extracted free amino acids increased by 68.0, 68.6, and 78.8% (P < 0.05) from their initial levels to 2930, 2422, and 1573 mg/mL after 30 d of fermentation for PRF, PSF, and CF fish pastes, respectively, of which, glutamic acid, aspartic acid, alanine, lysine, and leucine were the major amino acids (>100 mg/mL). The concentrations of both formaldehyde-reactive nitrogen and ammonia nitrogen extractives increased significantly (P < 0.05) during fermentation, following the order of PRF > PSF > CF. Low amounts of biogenic amines (<25 ppm) were produced in all samples. Sensory panel evaluation showed that PRF fish pastes had desirable aroma and taste. The douchi-inoculated fermentation could be a novel technique for expanding the utilization, consumption, and the economic values of silver carp meats.