Effect of home preparation practices on the content of provitamin A carotenoids in coloured sweet potato varieties (Ipomoea batatas Lam.) from Kenya

摘要

The content of beta -carotene was determined in raw peeled, boiled peeled and roasted peeled roots of six orange- and yellow-fleshed sweet potato varieties from Kenya to evaluate their vitamin A potential before and after household preparation. The boiling and roasting procedures were similar to traditional methods used in Kenya. Dried products, chips and flour, of the variety Zapallo were also analysed. The varieties differed in dry matter and beta -carotene content (1240-10,800 micro g/100 g fresh weight (FW)) and thus in vitamin A content (100-830 RE/100 g FW). As sweet potato roots are consumed after heating, the loss of all-trans- beta -carotene during preparation should be taken into account. Boiling of roots of the selected varieties seemed to result in a higher true retention (TR) of all-trans- beta -carotene than roasting and TR of all-trans- beta -carotene seemed to be dependent on the variety (42-128%). Preparation of chips by drying resulted in a significant reduction of the all-trans- beta -carotene content of approximately 21%, which was further reduced when flour was produced from chips. The varieties Tainung and SPK-004 can be recommended for consumption especially after boiling in order to enhance the vitamin A intake in Kenya. Both varieties have a high content of vitamin A, the losses after boiling are rather low and both varieties have high consumer acceptability..