Determination of antioxidant activity and classification of bioactive compounds extracted from Xinomavro variety grape pomace using ultrasound extration

Abstract

This paper aimed to discover the optimal conditions for ultrasound-assisted extraction of bioactive compounds from Xinomavro variety grape pomace. The extraction parameters were the solvent type and time. The variables analyzed were total phenolic content (TPC), antioxidant activity through DPPH experiments, and quantitative analysis of flavonols and hydroxycinnamic acid derivatives. Grape pomace of Xinomavro exhibited high antioxidant capacity. In particular, samples treated with water: ethanol (1:1), exhibited the highest rates of antioxidant activity, followed by the ones treated with absolute ethanol. The same phenomenon was observed in case of TPC, flavonols and hydroxycinnamic acid derivatives. However, in case of both flavonols and hydroxycinnamic acid derivatives, the differences between each solvent were not significant compared to the experiment of total phenolics. The relationship between yield and time was not proportional.