Hot water extraction, ultrasound, microwave and pectinase-assisted extraction of anthocyanins from blue pea flower

•Blue pea flower is a rich source of anthocyanins.•Blue pea flower mainly contains acylated anthocyanins.•Delphinidin-derived anthocyanins are prominent in blue pea flower anthocyanins.•Blue pea flower anthocyanin is a potential natural blue colouring agent.•Microwave-assisted extraction was the best to extract blue pea flower anthocyanins. This study investigated the hot water extraction, ultrasound, microwave, and pectinase-assisted extraction of anthocyanin pigments from petals of blue pea flowers. The effect of substrate: solvent ratio, extraction time, and extraction temperature on the extraction yield, total anthocyanin content (TAC), and total phenolic content (TPC) of the anthocyanin extracts obtained from hot water extraction were determined. Substrate: solvent ratio of 1:15 at 50 °C for 30 min was the best extraction condition to obtain an anthocyanin extract with high extraction yield, TAC, and TPC. With these conditions, the extraction yield, TAC and TPC of the anthocyanin extract of blue pea flower were 56.9 ± 5.85%, 6.74 ± 0.21 mg cyanidin-3-O-glucoside/g (mg CGE/g) and 81.1 ± 3.82 mg gallic acid equivalent/g (mg GAE/g), respectively. Microwave-assisted extraction was the best method to obtain an anthocyanin extract with high extraction yield, TAC, TPC, and good antioxidant activity. Delphinidin-3-(trans-p-coumaroyl)-glucoside was the most prominent anthocyanin in the anthocyanin extracts.