Indigenous floriculture crops | Indigenous/traditional African vegetables | Sweet Potatoes | Potatoes | Genebanks | Biotechnology |Commercial Vegetables

Orange-fleshed sweet potato (OFSP) has a tremendous potential for agro-processing due to the variety of products that can be processed out of it e.g. baked products, crisps, French fries, pasta, beverages. Though OFSP is not a common commodity in South Africa, it is essential that OFSP characteristics are investigated to determine their suitability for processing of flour and extruded products. Hence the need for South Africa to exploit this advantage.  Besides, previous research focused on converting OFSP into various products. However, little has been reported about the relationship between processing methods, sensory characteristics and the physico-chemical parameters of the storage roots.

The ARC made specific investment in research of orange-fleshed sweet potato flour. One study investigated temperature-time combinations in hot-air convection oven drying to obtain optimum β-carotene content (Moloto et al., 2021). Flours made from  OFSP varieties Bophelo and Impilo at any of drying temperatures and times at 70°C for 4.4 hrs, 56°C for 6.5 hrs and 60°C for 6.5 hrs, indicated favourable gelling properties and cost of drying, implying that these can be used at household level and in food industries as thickeners from both cultivars.

Considering that South Africa receives an average of 5.5 KWhm-3Solar drying is a solution applicable to South Africa. The use of solar drying for OFSP flour production. The effect of thermal processing (e.g. indirect solar drying) on phytonutrient contents of popular local cultivars (Ndou, Monate, Beauregard, Bophelo, 199062.1 and C5-1) was investigated and found that epicatechin, vanillic acid, protocatechuic acid, p-hydrobenzoic acid and 2-caffeoyl-L-tartaric acid are some of the predominant phenolic compounds present (Selokela et al., 2021).

The young leaves and tips of sweet potato are used as green vegetable. Evaluation of the phenolic compounds and antioxidant properties in leaves of different sweet potato cultivars and demonstrated that the leaves of local cultivars Bophelo and Blesbok have the potential to become functional ingredients for food processing (Phahlane et al., 2021).

An exciting new collaborative effort started in 2021, where the ARC and SANBio-CSIR plans to develop novel OFSP products. One product is shelf-stable OFSP puree which has been scaled to industrial production by SinnovaTek (USA).

Local OFSP farmers and agro-processors are expected to benefit from these technologies in terms of increasing OFSP production as well as income generation derived from processing of various OFSP products. Increased production of OFSP varieties will greatly contribute towards addressing malnutrition and food insecurity in South Africa.



Moloto, P.I., Mosala M, Omolola A, Jideani A, Laurie SM. 2021. Optimization of hot-air drying conditions on functional properties of flour from dried South African sweet potato cultivars (Impilo and Bophelo) using response surface methodology. Food Science and Technology International (Campinas) 41(1):39-46.

Phahlane, C.J., Laurie, S.M., Shoko, T., Manhivi, V.E., Sivakumar D. 2021. An evaluation of phenolic compounds, carotenoids, and antioxidant properties in leaves of South Africa cultivars, Peruvian 199062.1 and USA's Beauregard. Frontiers in Nutrition 8:773550. doi: 10.3389/fnut.2021.773550

Selokela LM, Laurie SM, Sivakumar D. 2021. Impact of different postharvest thermal processing on changes in antioxidant constituents, activity and nutritional compounds in sweet potato with varying flesh colour. South African Journal of Botany 144: 380-388