Effect of Pasteurization of Pomegranate Juice by Cold Plasma Method on Its Bioactive Compounds Content and Microbial Load

In recent years, in order to preserve food and destroy vegetative microorganisms, foods have been thermally processed, which can cause physicochemical changes and reduce the absorption of some nutrients. The present research was to evaluate and compare the physicochemical properties and microbial quality of pomegranate juice pasteurized by the cold plasma method (at 20, 40, and 60 kV, for 5,10, and 15min under air gas) with those of pomegranate juice pasteurized by the thermal method (at 95°C for 5sec) without any process. The results showed that the cold plasma procces had a significant effect (p≤0.05) on physicochemical properties (acidity, pH and Brix), bioactive compounds (anthocyanin, total phenol and vitamin C), color indexes (a*, b* and L*) and microbial load (mold, yeast, aerobic bacteria and coliforms). As the voltage increased from 20-60 kV, time increased from 5-15 min, the acidity, Brix, and color indexes a* and b increased significantly (p≤0.05), and the pH value, bioactive compounds, index L, and microbial load decreased significantly (p≤0.05). Results showed that pomegranate juice pasteurized by the cold plasma method at 20kV for 5min under air gas had the most similar physicochemical properties (acidity, pH, and Brix), bioactive compounds, and color properties (a*, b* and L*) to control sample (without any process) and was introduced as the superior treatment. Therefore, it was found that plasma treatment was effective in inactivating the microorganisms, and this new non-thermal method could be used for the pasteurization of pomegranate juice instead of heat treatment.