Functional constituents of fruit juices after acetic acid fermentation

Abstract

Fruits are dense sources of nutrients with many functional properties. Acetification of fruit juices generates different types of fruit vinegar with a variety of flavors and uses. In this study, Alcoholic juices fermented by employing Saccharomyces cerevisiae were subjected to acetification by pre-cultured Acetobacter pasteurianus PP21 at both 30 °C and 36 °C temperatures and they were tested for their Brix value, titratable acidity, alcohol content, antioxidant activity, phenolic content and flavonoid contents. Compared to the acetic acid production at 36 °C, both mango and jackfruit juices showed their peak acetic acid production of 4.5 ± 0.015% (w/v) and 4.2 ± 0.04% (w/v) respectively, at 30 °C. The final Brix value of mango and jackfruit juices subjected to acetification at 30 °C and 36 °C was found to be constant at 3.6, 5.7, and 3.1, 5.7 °Bx respectively. Furthermore, the final alcohol level of all the vinegar samples was found to be less than 0.5% (v/v). Moreover, the antioxidant activity, phenolic content and flavonoid contents of both mango and jackfruit juices after acetification were significantly higher (p<0.05) at 36 °C compared to vinegar produced at 30 °C. As per the results, both mango and jackfruit juices can be successfully used as a potential source of functional constituents in vinegar production at both 30 °C and 36 °C.