Investigating Nutritional, Antioxidant and Sensory Characteristics of the Spring Onions Treated by Cold Plasma

Quality and shelf-life increases of vegetables are expected after processing by cold plasma. Optimizing process factors can be effective in persevering quality and nutritional characteristics and increasing shelf life of the vegetable products. Therefore, this study investigated optimization of the process factors of cold plasma as well as investigating shelf life of spring onions.

In this study, process factors of the dielectric barrier discharge type cold plasma including process times (5, 10 and 15 min), distances of the upper electrode from the water surface (4, 7 and 10 cm) and voltages (6, 8.5 and 11 kV) were optimized using response surface methodology. Then, changes in nutritional and sensory characteristics of the onion leaves treated by cold plasma in the optimal state of variables and during storage in the refrigerator (4 °C) were investigated.

Results showed that the highest level of vitamin C retention and antioxidant activity of the onion leaves were achieved using 8 kV, 8.83 min and 6.6 cm. Plasma-treated leaves included higher vitamin C contents than that the control group did and showed increases in antioxidant activity during ten days of storage at refrigerator temperature.

Results of the study showed that the variables of voltage and process time included significant effects on improving antioxidant activity and vitamin C content of the onion leaves treated by cold plasma dielectric barrier discharge type.