Effect of Light on Stability of Anthocyanins in Ethanolic Extracts of <i>Rubus fruticosus</i>

Abstract

Blackberry ( Rubus fructicosus ) is one of the fruit with the highest concentration of anthocyanins; however, its use is limited for making jams, jellies and liqueur, and recently, fruit concentrates in combination with pomegranate, blueberry and grape. One of the main problems with these pigments is their poor stability in solution, mainly in beverages as liqueur and juices, which depends on factors such as chemical structure, pH, temperature, light, water activity, and presence of oxygen. The effect of light on total monomeric anthocyanins content as well as the degradation rates and browning of two blackberry ethanolic extracts is to establish the conditions for storage of liqueur without adding artificial food coloring. The initial content of anthocyanins on extract without storage was 106 mg?l -1 . The study assessed the light irradiation effect on the anthocyanins of blackberry ethanolic extract. The anthocyanins degradation followed the second order reaction kinetics with respect to illuminance of the light source. The t 1/2 value at high illuminance (3968.30 lx) was 28.20 hours.