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Abstract
The main purpose of this work was to maintain the integrity and
contents of vitamin C and carotenoids. Carrots, sweet potatoes and mango were served as main sources of carotenoids while guava, lime and orange were considered as major reservoir for vitamin C. Two physical methods ,i.e., microwave and γ-irradiation treatments were applied in order to keep vitamin C and carotenoids of the aforementioned natural sources. The samples were exposed to γ-irradiation doses at 0.5, 1.0, 1.5, 2.0, 2.5 and 3 KGy and microwave treatment for 1, 2, 3 and 4 min emitted from an oven fixed at low power setting. The results indicate that vitamin C and carotenoids of the samples were variably degraded depending upon the conditions of treatments. Microwave treatment caused decreases in the levels of vitamin C of lime, orange and guava and the extent of reduction was dependent upon the exposure time. On the contrary, microwave treatment induced small reduction of vitamin C of mango juice, sliced sweet potato and carrots. γirradiation treatment induced gradual and significant decreases in the vitamin C levels of lime, orange and guava juices. In contrast, γ-irradiation caused an increase in the levels of carotenoids for mango juice, sliced carrots and sweet potatoes. In general, γ-irradiation treatment was better than exposure to microwaves for retention of vitamin C and carotenoids and hence extending the shelf life of the food sources under study. The mode of action of these physical methods on vitamin C and β-carotene content is discussed.