Effect of gamma irradiation on the microbiological quality and antioxidant activity of fresh vegetable juice

Abstract

A fresh vegetable juice has become a new functional food available for dieting and health. However, it poses a microbiological hazard to the consumer because it is distributed and consumed without any cooking. In this study, we applied the radiation sterilization of fresh vegetable juice, and the effectiveness of γ irradiation for inactivating Salmonella typhimurium and Escherichia coli in the carrot and kale juice was investigated. D 10 values of S. typhimurium in the carrot and kale juice were 0.445±0.004 and 0.441±0.006 kGy, while those of E. coli were 0.301±0.005 and 0.299±0.006 kGy. The test organisms (inoculated at 10 7 cfu/ml) were eliminated by irradiation at 3 kGy. The total phenol contents of the irradiated juice during 3 days of storage at a cold chain temperature (10 °C) increased significantly ( P < 0.05 ), while those of the non-irradiated juice decreased ( P < 0.05 ). The antioxidant capacity of the irradiated carrot juice was higher than that of the non-irradiated control. Therefore, it was concluded that irradiation treatments of carrot and kale juice improve the microbiological safety with maintaining or even enhancing the antioxidative activity.