Trans-β-carotene, selected mineral content and potential nutritional contribution of 12 sweetpotato varieties

The content of trans-β-carotene and selected minerals was determined in 12 sweetpotato (Ipomoea batatas) varieties produced at 4 agro-geographical production sites in South Africa. All 9 orange-fleshed varieties have the potential to contribute ≥100% of the recommended dietary allowance of 4–8 year-old children for vitamin A, 27% for magnesium, 15% for zinc and 11% for iron. Orange-fleshed varieties were superior to cream-fleshed ones in calcium and magnesium content. The trans-β-carotene content of the varieties varied over the geographical sites. The mean content in the 9 orange-fleshed varieties was between 5091 and 16,456 μg/100 g fresh weight. The mineral content in fresh roots of the 12 varieties ranged from 34 to 63 mg/100 g for calcium, 15 to 37 mg/100 g for magnesium, 28 to 51 mg/100 g for phosphorus, 191 to 334 mg/100 g for potassium, 0.73 to 1.26 mg/100 g for iron, and 0.51 to 0.69 mg/100 g for zinc. Variation within varieties over geographical sites could be ascribed to differences in soil mineral content, soil pH and the interaction of these. The variation in nutritional content of sweetpotato indicated here, needs to be considered in varietal selection for different production sites and in calculating nutrient contribution of sweetpotato toward dietary intake.