Increasing urbanization in developing countries has resulted in busier lifestyles, accompanied by consumption of fast foods. The consequence is an increased prevalence in noncommunicable diseases (NCDs). Food-based approaches would be cheaper and more sustainable in reducing these NCDs compared to drugs, which may have side effects. Studies have suggested that consuming functional foods could potentially lower NCD risks. Sweetpotato is regarded as a functional food because it contains bioactive compounds. Recently, sweetpotato has gained attention in sub-Saharan Africa (SSA), but research has focused on its use in alleviating micronutrient deficiencies such as vitamin A deficiency, particularly the orange-fleshed variety of sweetpotato. Some studies conducted in other parts of the world have investigated sweetpotato as a functional food. There is a need to characterize the sweetpotato varieties in SSA and determine how processing affects their bioactive components. This review highlights some of the studies conducted in various parts of the world on the functionality of sweetpotato, its bioactive compounds, and how these are influenced by processing. In addition, the potential health benefits imparted by sweetpotato are expounded. The knowledge gaps that remain in these studies are also addressed, focusing on how they can direct sweetpotato research in SSA.

The Sustainable Technology for Orange and Purple Sweetpotatoes (STOPS) project, led by researchers from Tuskegee University, USA, identified gaps in the value chain from production, processing, product development to consumption of sweet potato, aimed at addressing vitamin A deficiency (VAD) and improving the health and nutritional status of vulnerable populations in rural communities in Ghana. The orange sweet potato (OSP) could be an inexpensive, year-round, rich source of β-carotene, a precursor of vitamin A. The anthocyanins that account for the purple pigmentation in the purple variety are powerful antioxidants with good bioavailability to be easily absorbed by the body. The STOPS project promotes the utilization of both varieties into value-added products from the root including flour, yogurt, and bread. Sweet potato-based bread, TUO vitabread, prepared from a composited wheat flour and OSP puree at a ratio of 2.5:1 ("as-is" basis) was compared with traditional wheat (white) bread on the Ghanaian market in compositional and sensory analyses. The proximate composition (moisture, protein, fat, ash and carbohydrate by difference) and energy content were not statistically different (P>0.05), although TUO vitabread contains 18% more moisture than the white bread. The β-carotene and lutein concentrations in the OSP-based bread were approximately 6-fold higher (P=0.01). The TUO vitabread could meet 17% of the daily adequate intake of vitamin A for a 1-to 3-year-old child consuming about 50 g of the bread, but only 3% from the white bread. Consumer preference assessment of 50 undergraduate students showed a high preference for the OSP puree-based bread but further work on extension of shelf-life under ambient conditions is warranted. Thus, the inclusion of OSP in the traditional diet can be an inexpensive and year-round source of dietary β-carotene to complement the vitamin A supplementation programme to reduce VAD in children.

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