The long-term effect of thermal pasteurization (TP) and high-pressure processing (HPP) of orange juices stored under refrigeration, on the bioactive components and antioxidant activity, was compared. Total phenolic content (TPC), flavonoid, anthocyanin, and carotenoid contents, the individual content of major phenolic components, and the antioxidant activity, were evaluated in TP- and HPP-treated juices over a 36-day period. At day 0, no significant differences in TPC, and a decrease in carotenoid content after both treatments, were observed. TP caused a decrease of flavonoid and anthocyanin contents, while HPP increased flavonoid content. Three major phenolic components were identified: apigenin-6,8-di-C-glucoside, naringenin-7-O-rutinoside, and hesperetin-7-O-rutinoside, the latter increasing ca. 45% immediately after HPP. During storage, a decrease in TPC, and in the anthocyanin and carotenoid contents of both treated juices was observed, with higher anthocyanin and phenolic contents in HPP juices. A significant increase of hesperetin-7-O-rutinoside content was observed in HPP juice. Both treatments caused a decrease (26% and 13%, respectively) of antioxidant activity. Most of the kinetic profiles followed zero-order patterns, with HPP juices showing a considerably higher half-life than TP ones. These results clearly demonstrate the advantages of HPP for orange juice preservation allowing, also, their nutritional benefits to be enhanced by increasing the content of some bioactive components.
Keywords: antioxidant activity; bioactive compounds; high pressure; orange juice; phenolic compounds; refrigerated storage; thermal processing.