Proximate composition and vitamin A contribution of biofortified orange fleshed sweet potato value added products

Abstract

Orange fleshed sweet potato (OFSP) is rich in provitamin A carotenoids and can thus be utilized to tackle Vitamin A deficiency (VAD) in Sub-Saharan Africa (SSA). Puree with high amounts of β-carotene processed from OFSP roots is currently being incorporated in baked products such as bread, cakes, biscuits, and buns. The objective of this study was to evaluate the nutritional composition of OFSP puree supplemented food products, that is, bread, buns, flakes, cakes, biscuits, muffins, soft cookies, golden biscuits and whole wheat flour bread. The composite products made from OFSP puree were analyzed for β-carotene content and proximate analysis. The highest concentration of β-carotene (19.86 mg/100g) was obtained in OFSP flakes. The concentration in buns with 20% puree was 0.58 mg/100g, while bread with 35% puree had a concentration of 3.02 mg/100g. Biscuits, cookies and cakes with high puree of 40% had β-carotene concentrations of 2.39, 1.83, and 2.30 mg/100g respectively. These concentrations are lower than in bread with 35% puree, and we see different proportions of ingredients and other factors such as cooking method, duration of cooking also play a major role in the final β-carotene concentration of the products. The total Retinol Activity Equivalents (RAE) for the OFSP products were significantly different with bread (35% puree) having a higher concentration of 216.67 µg/100g and OFSP buns (20% puree) having a lower concentration of 41.19 µg/100g. Orange fleshed sweet potato flakes had the highest concentration of 1443.2 µg/100g and whole wheat flour bread having the least of 6.9 µg/100g. The moisture content, total ash, crude fiber, crude fat, crude protein, and carbohydrate content of the OFSP products varied between 2.4-29.7%, 0.7-2.4%, 1.0-4.5%, 0.7-18.1%, 5.1-7.9% and 50.7-83.7%, respectively. The findings of this study show that different proportions of OFSP puree: wheat flour is not the only determinant on the final β-carotene concentration of the different OFSP products, the type and quantity of ingredients used, cooking time and method also contribute to the VA content. Diversification of OFSP food products helps increase its consumption and its added value. Key words: Beta-carotene, Orange fleshed sweet potato, puree, Sweet potato, Vitamin A