Effect of Ultraviolet-C Combined with Heat Treatments on the Quality Properties of Orange Juice

The effects of ultraviolet-C (UV-C) combined with heat (50 ℃) treatments and traditional pasteurization (P) on the safety, physical-chemical properties and nutritional values of freshly squeezed orange juice were compared in the present study. The best combined way was obtained by comparing the effects of different combinations of UV-C and heat on the microorganisms in orange juice. The effects of the best combined ways on the physical-chemical properties and nutritional values of orange juice were further explored. The results showed as follows: UV-C and heat had a synergistic inactivation effect on the microorganisms. The best combined way was UV-C and heat treatment simultaneously. UV-C treatment at 50 ℃ for 10~30 min (UH10, UH20, UH30) had no significant effect on the pH, total soluble solids, titratable acidity and color of orange juice (P>0.05). Compared with P, the levels of ascorbic acid in orange juice treated with UH10, UH20 and UH30 increased by 45.59%, 38.31% and 32.57%, respectively; the level of total phenolic increased by 4.78%, 19.50% and 32.35%, respectively; the carotenoid content increased by 46.12%, 36.33%, 30.20%, respectively; the scavenging capacities of DPPH radical increased by 8.45%, 19.07%, and 26.58%, respectively; and the scavenging capacities of ABTS radical increased by 11.23%, 18.40%, and 22.23%, respectively. These results indicated that UV-C combined heat treatments could improve the safety of orange juice and increase its nutritional value compared with traditional pasteurization.