Increase in colour stability of pomegranate juice against 5-hydroxymethylfurfural (HMF) through copigmentation with phenolic acids.

Abstract

Anthocyanins are responsible for both attractive colour of pomegranate juice (PJ) and its health-promoting effects against cancer and coronary heart disease. However, 5-hydroxymethylfurfural (HMF) at some concentrations causes anthocyanin degradation. The present study aimed to reduce the degradation of PJ anthocyanins as a result of HMF at various concentrations (0-20 mg L-1 ) through phenolic acid [PA; ferulic (FA), gallic (GA) and caffeic acids (CA)] copigmentation during storage at 20 °C. A strong correlation (r = 0.872) was found between anthocyanin degradation rate and HMF concentration in PJ without PA addition. An increase in HMF concentration during storage caused faster (< 32%) anthocyanin degradation. However, PA addition reduced (< 60 times) the HMF formation rate. The lowest HMF formation rates (0.07-0.28 day-1 ) were determined in PJ with added GA. Although GA caused an important increase in content of cyanidin-3-glucoside (16-42%), which is major PJ anthocyanin, against HMF at all concentrations, CA (15%) and FA (28%) increased cyanidin-3-glucoside content against 10 mg of HMF L-1 . FA maintained its protection effect against the highest HMF concentration (20 mg of HMF L-1 ), but CA lost its protection effect. Generally, FA increased stabilities of hyperchromic effect (HE) (9.6-27.7%) and colour density (CD) (57.1-74.3%) at all HMF concentrations, although CA increased HE stability (19.8-37.7%) in the presence of 10 and 20 mg of HMF L-1 . Interactions of 'all individual anthocyanins-FA' and 'delphinidin-based anthocyanins-GA/CA' resulted in copigmentation. FA addition was recommended to increase CD and HE for PJ containing HMF between 3.1-5.6 mg L-1 , whereas the addition of GA was recommended to increase anthocyanin stability for PJ containing 12.0 mg of HMF L-1 . © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.