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Research on Crops

Influence of peeling forms and processing methods on total phenolic, beta-carotene and vitamin C of different sweet potato (Ipomoea batatas) cultivars 


DOI: 10.31830/2348-7542.2026.ROC-1344    | Article Id: ROC-1344 | Page : 570-576
Citation :- Influence of peeling forms and processing methods on total phenolic, beta-carotene and vitamin C of different sweet potato (Ipomoea batatas) cultivars. Res. Crop. 27: 570-576
T. M. RAPHALALANI AND M. Y. MAILA yvonne.maila@ul.ac.za
Address : Department of Plant Production, Soil Science and Agricultural Engineering, Limpopo Agro-Food Technology Station, University of Limpopo, Private Bag x1106, Sovenga, 0727, Polokwane, South Africa
Submitted Date : 25-07-2026
Accepted Date : 13-08-2026
Online Published:

Abstract

The nutritive value of sweet potatoes has attracted interest in the culinary industries because of their high antioxidant. The root vegetable can be eaten raw, but preferred baked, boiled or roasted. However, excessive processing may alter its nutritive value. The study examined the effects of peeling forms (PFs) and processing methods (PMs) on the bioactive compounds of four sweet potatoes (‘Bophelo’, ‘Blesbok’, ‘Mvuvhelo’ and ‘Mafutha’). The five-months tuberous roots were analysed for total phenolic (TP), beta-carotene (BC) and vitamin C. Each sweet potato cultivar was set in a 2 × 3 factorial experiment in a completely randomised design with five replicates. The study included PFs [unpeeled (UP) and peeled (P)] as the first factor and PMs (raw, boiling and baking) as the second factor. Boiled and baked sweet potatoes in both PFs showed higher TP in UP baked ‘Bophelo’ and ‘Mafutha’, followed by UP boiled ‘Mvuvhelo’ and P baked ‘Blesbok’, with 80.61, 76.72, 76.68 and 64.30 mg GAE/100 gdw of TP, respectively. Beta-carotene was the highest in UP raw ‘Bophelo’ (standard), and UP baked ‘Mvuvhelo’ with 75.62 and 39.47 µg/100g of BC, respectively. Vitamin C was the highest in UP boiled ‘Bophelo’, followed by UP baked ‘Mafutha’ and P baked ‘Mvuvhelo’ with 66.42, 5.29 and 31.62 µg/100g, respectively. In conclusion, the interaction of PFs × PMs influenced the bioactive compounds, with the highest TP and vitamin C found in UP baked ‘Bophelo’ and ‘Mafutha’, while the highest BC was observed in the UP raw ‘Bophelo’ (standard) sweet potatoes.

Keywords

Orange-fleshed sweet potato “poor man’s crop” tuberous root white-fleshed sweet potato 

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