Ultrasonic assisted extraction of anthocyanins from rose flower petal in DES system and enzymatic acylation

Abstract

Herein, the anthocyanins from rose were extracted, purified and identified by ultrasound-assisted deep eutectic solvents (DES), the resin, and ESI-Q-TOF-MS, respectively. The purified anthocyanins were modified through acylation by means of enzymatic catalysis method to improve the stability of anthocyanins. Compared with traditional extraction agents (ethanol), anthocyanins extraction rate was significantly improved when choline chloride/lactic acid was chosen as extraction solvent, and reached 8.265 mg g−1. The ESI-Q-TOF-MS detection results showed that the main component of the anthocyanins was peonidin-3,5-di-O-glucoside with 65.93% content. Meanwhile, the maximal acylation rate was 95.13% under optimal conditions (0.25 g of anthocyanin, 2.5 mL of pyridine, 4 mL of methyl benzoate; 400 mg of Novocain 435 lipase addition; a water bath at 50 °C under negative pressure of 0.09 Mpa for 9 h). Furthermore, the loss rate of acylated anthocyanins was significantly lower than that of natural anthocyanins under the same temperature or light conditions, and the acylation of anthocyanin could significantly improve stability against temperature, light and pH. The acylated anthocyanin exhibited excellent free radical scavenging activities for DPPH and ABTS+, and IC50 values (4.451 μg mL−1 for DPPH and 7.760 μg mL−1 for ABTS+) displayed its high antioxidant activity.