Optimizing Production of Liquid-State Fermented Bran Vinegar and Study on Its Quality of Flavor

Abstract:

In order to improve the quality of liquid-state fermented vinegar，based on the traditional techniques，bran leachate was added into fermentation system，and Acetobacter pasteurianus isolated from the normal grains of Sichuan bran vinegar was inoculated. The significant factors which influence acetic acid fermentation were confirmed by single factor experiment，then the fermentation process was optimized by response surface methodology designed by Box-Behnken principle. The optimum fermentation conditions were as follows：the addition quantity of bran koji was 1.11%，the inocula biomass acetic acid bacteria was 13.71%，fermentation temperature was 31.5 ℃. Under these conditions，the acid production reached 68.48 g/L. Using liquid vinegar obtained from one factory at Sichuan as a control，the quality of liquid-state fermented bran vinegar was estimated with sensory evaluation，volatile constituents and free amino acid indexes. The results showed that the liquid-state fermented bran vinegar possessed pure taste and unique aroma. 20 volatile components and 17 free amino acids were identified in the liquid-state fermented bran vinegar. The total content of free amino acids was 805.29 mg/dL. Quality of liquid-state fermented bran vinegar was significantly improved.