Ultrasound processing of verjuice (unripe grape juice) vinegar: effect on bioactive compounds, sensory properties, microbiological quality and anticarcinogenic activity

Verjuice is one of the alternative fruit juices recently obtained from unripe grapes. In this study, the aim was primarily to optimize the process conditions for the enrichment of bioactive components in verjuice vinegar with ultrasound treatment. For this purpose, ultrasound treatment was applied to vinegar samples at different times (2, 4, 6, 8 and 10 min), different amplitudes (60%, 65%, 70%, 75% and 80%) and 26 kHz frequency. Total phenolic content (TPC), total flavonoid content (TFC), total antioxidant capacity (1,1-diphenyl-2-picrylhydrazyl (DPPH) and cupric reducing antioxidant capacity (CUPRAC) were evaluated for optimization (response surface methodology (RSM) and genetic algorithm (GA)) of process conditions. The sensory properties, microbiological quality and anticarcinogenic activity were then evaluated for the ultrasound-treated verjuice vinegar (UVV) (9.4 min and 68.7 amplitude result of RSM), traditional verjuice vinegar and pasteurized verjuice vinegar samples obtained from the optimization. At the end of the RSM optimization, CUPRAC (464.44 mg TEAC/mL), DPPH (0.694 mg TEAC/mL), TFC (70.85 mg CE/mL) and TPC (12.22 mg GAE/mL) were determined. RSM and GA results were found to be approximately the same. Analysis results showed that ultrasound-treated verjuice vinegar was enriched bioactive components compared to other samples. Verjuice vinegar showed anticarcinogenic effects. The UVV sample was generally appreciated in sensory evaluation. As a result, ultrasound treatment of verjuice vinegar was found to be successful.