Ultraviolet-C and ultraviolet-B lights effect on black carrot (Daucus carota ssp. sativus) juice

Effect of ultraviolet (UV-C and UV-B) radiation treatments depending on time (0, 5, 15, 30 and 60 min) on physicochemical properties, antioxidant activity, color and microbial load of the black carrot juice was evaluated. After UV-C and UV-B treatments, no significant changes were observed at pH, total phenolic and flavonoid contents and color of black carrot juices (p > 0.05). However, compared to the control and UV-C treated juice, the results showed better retention of total phenolic in UV-B treated juice. The antioxidant values in all UV treatment (except for UV-B 5 min) were observed to the increases. But in total monomeric anthocyanins, the decreases were generally determined. Based on rise in time and dose of the UV treatments, the browning degree of the juice increased. L, a, b and chroma values of juices were well maintained after the UV light treatments. UV treatments showed significant a reduction in bacterial load, especially UV-C.