Abstract:

The ultrasonic-assisted extraction of anthocyanins from the alcoholic fermentation broth of purple sweet
potato in vinegar production was optimized by response surface methodology. The influence of individual variables
such as material/solvent ratio, temperature, ultrasonic treatment time and output power as well as their interactions on
the extraction yield of anthocyanins was investigated. Moreover, the changes in the contents of major components in
the alcoholic fermentation broth after the extraction process were examined. It was found that the optimum extraction
conditions were as follows: material/solvent ratio 1:10 (g/mL), temperature 57.5 ℃ and ultrasonication for 25.7 min with
an output power of 300 W. Under these conditions, the extraction yield of anthocyanins was 87.16 mg/100 g dry matter.
After the extraction of anthocyanins, the contents of reducing sugar and amino nitrogen in the alcoholic fermentation
broth were increased by 70.04% and 17.00%, whereas the contents of total acid, lactic acid and alcohol were reduced by
9.5%, 16.1% and 8.1%, respectively.

Key words: purple sweet potato vinegar, anthocyanins, ultrasonic-assisted extraction, alcoholic fermentation broth