Phytochemical, antioxidant and pigment stability of acai (Euterpe oleracea Mart.) as affected by clarification, ascorbic acid fortification and storage

Acai juice at two clarity stages (semi-clarified and clarified) was compared to 100% a ai pulp following ascorbic acid fortification to evaluate phytochemical and antioxidant changes during storage at 4 and 20 degrees C. Cyanidin-3-rutinoside (202 +/- 5.8 mg/L) and cyanidin-3-glucoside (75 +/- 4.8 mg/L) were the predominant anthocyanins in a ai while 11 non-anthocyanin polyphenolics were detected in concentrations from 1.1 to 55 mg/L of ai ai pulp. Clarification of a ai pulp resulted in a 27% loss in total polyphenolics (197 +/- 6.9 mg gallic acid/100 mL) and in a 20% reduction in both total anthocyanins (729 +/- 3.4 mg/L) and antioxidant capacity (54 +/- 1.7 mu mol Trolox equivalents/mL). Anthocyanin degradation followed first order kinetics, with half-lives ranging from 9.4 to 43 days for cyanidin-3-glucoside and from 18 to 82 days for cyanidin-3-rutinoside. Fortification with ascorbic acid accelerated anthocyanin degradation in clarified juice at both storage temperatures, likely due to the loss of polymeric anthocyanin forms (21%) during clarification. Although clarification enhanced the amount of monomeric anthocyanins present in a ai juice which relates positively to the aesthetic quality, processing and handling regimes must be optimized to achieve maximum retention of their functional properties during storage. (C) 2006 Elsevier Ltd. All rights reserved.