Optimization of pretreatment and convective drying temperature for better nutritional and bioactive contents of orange fleshed sweet potatoes flour

Orange-fleshed sweet potatoes are a crucial staple crop in Eastern Africa, gaining prominence as a supplementary staple food rich in bioactive compounds and antioxidants. Exploiting their potential for functional food development to address food security and health concerns requires further exploration into postharvest processing in Africa for industrial and export purposes. This study optimized citric acid pretreatment and convective drying temperatures to preserve nutritional value and bioactive compounds in orange-fleshed sweet potatoes during flour production. Utilizing Response Surface Methodology with a face-centered cubic design, the effects of drying temperature (55–65 °C), citric acid pretreatment (1–3 g/100 mL), and soaking time (1–3 min) were examined. Numeric optimization identified the optimal conditions as: drying temperature of 58.5 °C, citric acid concentration of 2.8 g/100 mL, and soaking time of 1 min. Results showed that temperature, citric acid concentration, and soaking time significantly influenced the flour's nutritional and bioactive content. These optimized conditions effectively preserved the flour's nutritional and bioactive properties during drying, indicating the potential of orange-fleshed sweet potato flour, high in carbohydrates, beta-carotene, vitamin C, and polyphenol compounds, as a valuable functional ingredient in processed foods. • OFPs are a vital crop rich in nutrients and bioactive compounds. • Study optimized pretreatment and drying temperature for OFSP flour production. • Optimal drying of 58.5°, 2.8 g/100 mL citric acid, 1 min soak were the optimized conditions. • The optimized conditions preserved the nutritional and bioactive contents of the flour.