An effective method for extracting anthocyanins from blueberry based on freeze-ultrasonic thawing technology

Abstract The aim of this study was to develop an effective method for extracting anthocyanins from blueberry Vaccinium spp. (ABVS) using freeze-ultrasonic thawing technology (FUTE). Various parameters including freezing time, ultrasonic time, ultrasonic temperature and liquid–solid ratio were optimized by a single-factor design and multiple response surface methodology. The amounts of extracted anthocyanin and cyanidin-3-O-glucoside were measured by UV and HPLC respectively. The maximum yield of anthocyanins was achieved by freezing the samples for 5.43 min in liquid nitrogen at the liquid–solid ratio of 24.07:1 mL/g, followed by ultrasonic thawing at 41.64 °C for 23.56 min. The yield and antioxidant effects of ABVS extracted using FUTE, ultrasound-assisted extraction (UAE) and freeze-thawing extraction (FTE) were compared in order to determine the overall efficacy of FUTE. In addition to the higher content, FUTE extracted ABVS showed greater ability to scavenge DPPH·, ABTS+ and superoxide anions, and inhibit lipid peroxidation compared to the ABVS extracted by UAE or FTE. The reducing power of the FUTE-derived ABVS was intermediate between that of the UAE and FTE samples. Taken together, FUTE can rapidly and effectively extract ABVS and retain its antioxidant capacity.