Carotenoid contents in fresh, dried and processed sweetpotato products

In order to understand the effects of drying and processing sweetpotato storage roots into traditional baked food products on their pro-vitamin A contents, total carotenoids and β-carotene were colorimetrically determined. Fresh and cooked storage roots, dried and stored chips, and sweetpotato processed products were used. Flesh colors of the storage roots were white, yellow, cream, orange, and purple. Total carotenoids ranged from trace to above 9 mg β-carotene equiv./100 g of fresh storage root. Storage roots of high carotenoid content cultivars had consistently orange flesh; those with low to very low carotenoid contents were yellow or white. Hunter 'b' values were high and consistent for flours from orange- and cream-fleshed root cultivars, which could easily be used to predict total carotenoid and β-carotene contents. Drying sweetpotato storage roots at 65°C for 12 h reduced total carotenoid contents by 30%. Storing dried chips in ambient conditions for 11 months induced a 10% loss. Incorporation of flour made from orange-fleshed sweetpotato roots into buns, chapatis, and mandazis enriched the products in total carotenoids from 0.1 mg to 2.3 mg β-carotene equivalents per 100 g product. Results of this study suggest that increased consumption of orange-fleshed sweetpotatoes in either fresh or processed form can contribute in alleviating dietary deficiency of vitamin A.