Effects of different acetic acid bacteria strains on the bioactive compounds, volatile compounds and antioxidant activity of black tea vinegar

This study intends to produce a black tea vinegar (BTV) from low-quality bulk black tea in order to increase its consumption and added value, and to benefit from its functional characteristics. Three strains (Acetobacter sp. GDMCC1.152, Acetobacter pasteurianus GDMCC1.67, and Acetobacter aceti ATCC15973) of acetic acid bacteria (AAB) were inoculated into black tea infusion (BTI) with ethanol to produce BTV, and their effects on bioactive compounds, antioxidant activity, and volatile compounds in the vinegars were revealed. The results showed that the three strains were suitable for the production of BTV, and the vinegar quality was the best after acetic acid fermentation for 6 days. Compared with BTI, the contents of organic acids and volatile compounds and the antioxidant activity of the vinegars increased significantly. Among them, the vinegar produced by GDMCC1.152 strain had the highest content of organic acids, tea polyphenols (TPs), thearubigins (TRs), theabrownines (TBs), and volatile compounds. It also possessed the strongest antioxidant activity and a rich taste with an apple-like aroma. In summary, AAB fermentation can effectively improve the flavor and quality of BTI and produce a new healthy product with high activity, and Acetobacter sp. GDMCC1.152 is the most suitable strain for the production of BTV.