Process optimization by response surface methodology and quality attributes of orange fleshed sweet potato (Ipomoea batatas L.) vacuum fried chips

Vacuum frying is a promising technology for the production of healthy and nutritional snacks. The optimization of vacuum frying technology was carried out using oranged fleshed sweet potato slices by using a three-level Box–Behnken design of response surface methodology. The orange fleshed sweet potato chips were prepared using vacuum fryer. The effects of different processing conditions on nutritional and sensorial qualities were studies. The variables considered for the study were frying temperature—FT (110–130 °C), vacuum pressure—VP (14.79–17.46 Kpa) and frying time—Ft (7–9 min) while the responses were moisture content, oil content, total carotenoid content, change in colour and texture. It was observed that increasing FT and VP at constant Ft decreases moisture content and decrease in oil content in chips with increase in FT and VP at constant frying time during the vacuum frying process. FT, VP, Ft significantly (p < 0.05) affected the retention of carotene content in fried chips. The results confirmed the significant (p < 0.05) effect of VP and Ft on the color of chips. It was also found that, increasing FT and Ft when VP was held constant and increasing FT and VP at a constant Ft gave lower breaking forces. By using the numerical optimizer the optimal conditions for vacuum frying was determined such as frying temperature 110 °C, vacuum pressure 16.12 Kpa and frying time 7 min. Having maximum retention of carotenoids in fried chips. When optimized, vacuum fried samples were compared with atmospheric fried samples; the former absorbed about 50.32% less oil, and retained higher carotenoid (6.32 mg/g), with lower breaking force (0.69 N). Sensory evaluation results showed accepted optimized vacuum fried samples in all the sensory attributes investigated.