Optimization of deep-fat frying conditions and quality attributes of orange-fleshed sweetpotato crisps by response surface methodology

Abstract

Response surface methodology with a central composite design was applied to study the effect of frying temperature (145–164°C) and time (2.4–6.0 min) on some quality attributes of crisps from two varieties of orange-fleshed sweetpotato (OFSP) roots [Mothers’ Delight (MD) and King J (KJ)]. Response models and optimized frying conditions were generated. Frying temperature and time significantly (p < 0.01) influenced moisture content (MC) and crispiness for both varieties (R2 = 0.87–0.95). Total carotenoids (TC), L*, orange and brown colours for MD variety, and a* for KJ variety, were also significantly (p < 0.05) affected but the trend varied between the varieties (R2 = 0.82–0.94). MD crisps had higher TC which reduced with increase in frying conditions. Orange colour of crisps which increased for MD but decreased for KJ, with increase in frying conditions, was an important sensory quality index. At the optimum frying conditions, 151.27 ⁰C/4.20 min for MD and 146.36 ⁰C/4.20 min for KJ, MD crisps had lower MC (2.85%) but higher oil content (30.04%), total carotenoids (3752.33 µg/100 g), crispiness (8.84) and orange colour (8.92) than KJ. Optimized MD crisps had lower sensory oiliness and higher consumer acceptance.