Functionality and characteristic changes of orange juice concentrates due to heat treatment

Functionality and characteristic changes of orange juice concentrates due to heat treatment

Fresh orange (Citrus sinensis (L.) Osbeck) juice was concentrated at 98±2°C for 0-24 hr, and periodically sampled concentrates of orange juice (COJs) were evaluated to investigate the changes in functionalities and characteristics during the heating process. Phenolic acids and flavonoids at T_(24) (after 24 h heating) were significantly higher than at T_0, (at time 0) except for rutin. The hesperidin content at T_(24) was 1.67 times that at T_0, and the sinensetin content increased 16.36 times over the 24-hour concentration period. EC_(50) values of reducing power at T_(20) and T_(24) were 2.13 and 5.67 times those at T_0 (p ＜ 0.05) respectively. The 2% and 3% COJs significantly inhibited the growths of Escherichia coli O157:H7 and Listeria monocytogenes, and the survival potential of E. coli in COJs was higher than that of L. monocytogenes. Moreover, COJs (at 100 μg/mL level) significantly suppressed TNF-α (1 ng/ml)- induced ICAM-l protein expression.