Fed-batch fermentation of onion vinegar using .

To produce onion vinegar with high efficiency, various fermentation conditions, such as varying initial ethanol concentrations and the addition of ethanol or onion juice were optimized. KFCC 11476P consumed ethanol at a rate of 0.125-0.140 g/h when the initial ethanol concentrations were 4, 5, and 6%, and the acidity of the fermentation broth reached the maximum level when the ethanol was completely starved. In the case of fed-batch fermentation with continuous feeding, when a small amount of ethanol and onion juice was continuously supplied into the broth after 30 h of fermentation, the acidity continued to increase up to 4.5% at 45 h. All the while, the remaining ethanol content of the fermentation broth was 1.13-1.69%. The maximum acidity of onion vinegar in the pilot-scale fermenter reached 4.6% at 48 h of which fermentation speed was five times faster than the general standard.