Effect of traditional open sun-drying and solar cabinet drying on carotene content and vitamin A activity of green leafy vegetables.

摘要

Eight vegetable varieties commonly consumed in Tanzania were either traditionally sun-dried or solar-dried, and the amount of provitamin A carotenoids were determined using HPLC. In fresh blanched leaves, contents of beta-carotene, alpha-carotene, 9-cis-beta-carotene and 13-cis-beta-carotene were 526-917, 12-39, 80-136 and 16-40 mug/g (DM basis), respectively. Average amounts of all-trans-beta-carotene in leaves after blanching, solar drying and open sun-drying were 662, 502 and 353 mug/g (DM basis), respectively; all were significantly different from each other (P <0.001). Average amounts of all-trans-alpha-carotene were 21, 15 and 8 mug/g (DM basis; P <0.05), and of 9-cis-beta-carotene were 101, 82 and 63 mug/g (DM basis; P <0.05) in the blanched, solar-dried and open sun-dried samples, respectively. Estimation of the amount of retinol equivalents provided by the dried vegetables in an edible portion of 100 g relish showed that solar-dried vegetables contributed more than the recommended level of vitamin A (between 120-275%), and on average 43% more retinol equivalents than relishes of open sun-dried vegetables. It is concluded that the amount of provitamin A-carotenes in traditionally treated vegetables were highly reduced by open sun-drying while solar drying resulted in significantly more retention of the carotenes. Consumption of a 100 g portion of solar-dried vegetable relish provided the RDI for vitamin A.