Abstract: In order to obtain a suitable acetic acid bacterial strain for the fermentation of jackfruit vinegar with improved acetic acid content and quality, acetic acid bacteria were isolated and purified from naturally fermented jackfruit vinegar, and identified by molecular biology based on 16S rRNA gene sequence and their fermentation characteristics were studied. The results showed that 5 strains of acetic acid bacteria were identified, including Aa723 and Aa941 (Acetobacter pasteurianus), Aa847 (A. fabarum), Aa747 (A. tropicalis), and Aa844 (A. aceti). Among these strains, Aa941 showed the best fermentation performance. After 96 hours of fermentation, the maximum acid yield of 38.70 g/L was obtained under the conditions of fermentation temperature 31 ℃ and ethanol concentration 4%, as well as the maximum alcohol-acid transform ratio of 74.85% under the conditions of fermentation temperature 30 ℃ and ethanol concentration 6%. Under the conditions of ethanol concentration 8% and fermentation temperature 30 ℃, the acid yield and alcohol-acid transform ratio were 25.11 g/L and 74.10% respectively. Aa941 could grow well under the conditions of fermentation temperature 37 ℃ and ethanol concentration 4%, and the acid yield and alcohol-acid transform ratio were 19.79 g/L and 65.10%, respectively, showing that the ethanol and temperature tolerance of Aa941 are superior to those of the commercial strain As1.41. It was found that strain Aa941 could ferment jackfruit wine into fruit vinegar with the characteristic aroma of jackfruit. Thus, it can be used as a starter culture for jackfruit vinegar fermentation.

Key words: jackfruit; vinegar; acetic acid bacteria; 16S rRNA; fermentation characteristics