Nutritional and chemical constituents of different cultivars of sweet potato (<i>Ipomoea batatas</i> L.) grown in South Africa

Abstract

Sweet potato is one of the most important crops being promoted for food security and nutrition in South Africa. This study investigated the nutritional and chemical compositions of four white-fleshed (Blesbok, Ndou, Monate, and Mvuvhelo) and three orange-fleshed (Bophelo, Impilo, and 199062.1) cultivars. The protein, ash, and crude fibre contents were analysed using standard AOAC procedures. The detection of fatty acids, sugar, and metabolites was carried out using Gas Chromatography–Mass Spectrometry (GC-MS). Carbohydrate and energy values were determined using standard methods. The results showed that Bophelo had the highest protein content (12.00%), with Blesbok having the lowest protein content (4.56%). The study also revealed that Impilo had the highest fibre (7.11%) and total sugar (22.21 %) contents. The highest ash content was found in 199062.1 (5.81 %) and the lowest was observed in Monate (4.50 %). Bophelo had the highest total fat content (0.650 %), with saturated, mono-saturated, and poly-saturated fats of 0.270 %, 0.050 %, and 0.270 %, respectively, while the lowest fat content was observed in Impilo (0.380 %), with saturated, mono-saturated, and poly-saturated fats of 0.225 %, 0.020 % and 0.135 %, respectively. The highest total carbohydrate content was found in Blesbok (76.72 %). Different fatty acids, including palmitic acid (C16), stearic acid (C18), arachidic acid (C20), oleic acid (C18:1), and linoleic acid (C18:2) were also found in the sweet potato cultivars. This study demonstrated significant variations in the chemical composition of the cultivars, providing valuable insights for informed dietary decisions on consumption.