Evaluation of the effect of slice thickness and drying temperature on selected characteristics of orange-fleshed sweet potatoes (Ipomoea batatas L.)

Abstract

Orange-Fleshed Sweet Potato (OFSP) is rich in beta-carotene, a precursor of vitamin A that combats Vitamin A Deficiency (VAD). High moisture content in OFSP makes it highly susceptible to spoilage and hence necessitates processing. Drying is a processing method that extends the shelf life of food products; however, high temperatures can degrade some essential nutrients. This study examined the effects of slice thickness (2, 4, 6 mm) and drying temperatures (50, 60, 70 °C) on drying kinetics and quality of OFSP. Drying parameters such as Effective Moisture Diffusivity (Deff) and Activation Energy (Ea) were determined. Beta-carotene content and total colour change (∆E) were evaluated. Drying data were fitted to six thin-layer models. Logarithmic model provided the best fit (R² = 0.999, χ² = 0.000 at 6 mm, 60 °C). Deffvalues ranged from 2.286×10⁻⁷ to 3.195×10⁻⁶ m²/s, and Earanged from 31.50 to 39.10 kJ/mol. The highest beta-carotene (29.12 mg/100 g) was retained at 6 mm, 50 °C, while the best colour (∆E = 62.02) was at 4 mm, 60 °C. Overall, 4 mm slices offered a balance between drying efficiency and quality retention. Findings support optimized drying of OFSP to improve storage, nutrition, and food security, contributing to Sustainable Development Goals (SDG) 1, 2, and 3.