Effect of Ultrahigh-Temperature Continuous Ohmic Heating Treatment on Fresh Orange Juice

The scope of this study is the effect of ohmic heating thermal treatment on liquid fruit juice made of oranges. Effects of ohmic heating on the quality of orange juice were examined and compared to those of heat pasteurization at 90 °C for 50 s. Orange juice was treated at temperatures of 90, 120, and 150 °C for 1.13, 0.85, and 0.68 s in an ohmic heating system. Microbial counts showed complete inactivation of bacteria, yeast, and mold during ohmic and conventional treatments. The ohmic heating treatment reduced pectin esterase activity by 98%. The reduction in vitamin C was 15%. Ohmic-heated orange juice maintained higher amounts of the five representative flavor compounds than did heat-pasteurized juice. Sensory evaluation tests showed no difference between fresh and ohmic-heated orange juice. Thus, high-temperature ohmic-heating treatment can be effectively used to pasteurize fresh orange juice with minimal sensory deterioration. Keywords: Ohmic heating; electroheating; orange juice; pasteurization; flavor; vitamin C