Preservation of Leafy Vegetables by Co-treatment with Refrigeration Process and ultraviolet radiation (UV-c) and its potential effects on bioactive compounds content and antioxidant activity

The present study was carried out to investigate the influence of ultraviolet radiation (UV-c) treatment on the stability of bioactive compounds and antioxidant activity in leafy vegetables (Molokhia, Spinach and lettuce) throughout refrigerated storage. The analysis of variance for the total phenolics, carotenoids and chlorophyll levels indicates that their values were significantly (P ≤ 0.05) affected by both the UV-C radiation and the refrigeration storage period. Initial total phenolics, carotenoids and chlorophyll levels for all UV-treated samples were significantly lower (P < 0.05) than those for the control samples. When the all selected leafy vegetables were included in the statistical analysis, there was a positive significant relationship between total phenolics (p≤0.05, r2 = 0.5182), total carotenoids (P≤ 0.01, r2 = 0.6827), total chlorophyll (P≤ 0.05, r2 = 0.6715) and antioxidant activity in control and UV-treated samples throughout refrigerated storage. Also, bacteriological analysis indicated that total aerobic bacterial growth (TABG) of molokhia, spinach and lettuce was recorded 4.21, 4.65 and 4.43 log10 cfu/g which increased by rates of 51.98, 43.92 and 54.34% for the untreated samples and 41.73, 33.32 and 42.45% for the UV treated samples after 8 days of refrigeration at 4 0C, respectively. .