Anthocyanin composition and storage degradation kinetics of anthocyanins‐based natural food colourant from purple‐fleshed sweet potato

Abstract

SummaryA natural colourant derived from purple‐fleshed sweet potato (PFSP) by ultrasound‐assisted solvent extraction was examined in terms of its anthocyanins and 6‐month storage stability under different conditions: avoid from light at 25 (AL25) and 37 °C (AL37) and under fluorescent light at 25 °C (FL25). This PFSP colourant mainly contained the following peonidin anthocyanins: peonidin 3‐p‐hydroxybenzoyl sophoroside‐5‐glucoside, peonidin 3‐feruloyl sophoroside‐5‐glucoside, peonidin 3‐caffeoyl sophoroside‐5‐glucoside, peonidin dicaffeoyl sophoroside‐5‐glucoside, peonidin 3‐caffeoyl‐p‐hydroxybenzoyl sophoroside‐5‐glucoside and peonidin caffeoyl‐feruloyl sophoroside‐5‐glucoside. The degradation ratios of PFSP anthocyanins (PFSPAs) under AL25, AL37 and FL25 were around 50.7%, 89.0% and 87.0% respectively. The FL25 and AL37 conditions had similar effects on the colourant's total colour change (ΔEab). The degradation kinetics followed the zero‐order reaction models. The PFSPAs were more stable during storage than other anthocyanins because they mainly consist of di‐acylated and double glycosylated forms of peonidin derivatives. These results may promote the application of PFSPAs as a novel natural colourant in food industry.