Recovery of antioxidants and oils from blackcurrant and redcurrant wastes by ultrasound-assisted extraction

Abstract

An investigation of the ultrasound-assisted extraction (UAE) of polyphenols and oils from blackcurrant and redcurrant pomaces was carried out. The aim of the study was to select optimal conditions for the UAE process in order to obtain polyphenol-rich extracts with highest total polyphenol content and highest antioxidant capacity. In case of oils, the optimization was focused on choosing the UAE parameters to achieve the highest oil yield and the longest oxidation induction times. The most effective conditions of UAE were provided by the results of response surface methodology procedure, which involved variables of time (2–10 min) and ultrasound amplitude (30%–80%). Solvents used for extractions were distilled water and n-hexane for bioactive compounds and oils extractions, respectively. In terms of polyphenol-rich fractions the most effective conditions were: amplitude of around 51% and 3 min time for blackcurrant pomace and amplitude of around 91% and 11 min time for redcurrant pomace. In case of oils, the amplitude of 99% and 11.5 min time were chosen for blackcurrant. For redcurrant seed oil it was the amplitude of 96% and extraction time equal to 12 min. The actual results obtained in optimized conditions were comparable to the results predicted by models. It was proved that response surface methodology could be useful tool in optimization of UAE process for blackcurrant and redcurrant polyphenol-rich extracts and seed oils.