Abstract: Semi-continuous submerged vinegar fermentation in a self-suction fermentor has the advantages of high production efficiency and short production cycle. However, the taste of the produced vinegar is not as good as desired. For increased non-volatile acid content and improved vinegar flavor, the traditional liquid-state fermentation process for vinegar production was modified by raw material selection, addition of saccharification agent and mixed-culture alcoholic fermentation. The vinegar production process was determined as follows: After addition of water, ground wheat was liquefied and saccharified by addition of 6.5% (m/m) flavor-enhancing saccharification agent at 35 ℃ for 1 h; afterwards, the substrate was inoculated with a mixture of 5% (V/V) lactic acid bacteria and 0.28 g/100 mL yeast, fermented at 32 ℃ for 4 d, and finally inoculated with acetic acid bacteria. The liquid-state fermentation carried out in shaking flasks yielded a product containing 0.47 g/100 mL non-volatile acids. The total acidity of vinegar produced in a 5 L self-suction fermentor by the semi-continuous submerged fermentation process was no less than 6 g/100 mL, and the volatile acid content was no less than 0.5 g/100 mL, both of which reached the requirements of the Chinese national standard.

Key words: self-suction, semi-continuous fermentation, vinegar, flavor