Optimization of deep-fat frying conditions and quality attributes of orange-fleshed sweetpotato crisps by response surface methodology
Cogent Food & Agriculture
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 (R 2 = 0.87-0.95). Total
... arotenoids (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 (R 2 = 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. Sururah Nasir ABOUT THE AUTHOR Sururah Nasir earned an M.Sc. degree in Food Processing and Storage Technology, and this study was an output of her research. Ganiyat Olatunde was the major supervisor while Abdurazaq Adebowale and Isaac Aiyelaagbe were co-supervisors. Ganiyat Olatunde specializes in Food Quality Control and Assurance. Her research activities involved studying the relationship between raw material composition, processing conditions and quality attributes of products. Her focus is on chemical and nutritional composition, as well as sensory attributes that determine consumer acceptance. Many of her studies have been on sweetpotato, a crop globally recognized as having the potential to solve the problem of household and national food and nutritional security in Sub-Saharan Africa. She has taken part in commissioned projects including the 'Sweetpotato for Health and Wealth in Nigeria' project; she worked with SMEs to develop technology and establish quality requirements for baked and fried products, incorporating provitamin A-rich sweetpotato varieties. PUBLIC INTEREST STATEMENT Optimized frying conditions generated in this study are expected to assist Small and Medium Enterprises to (i) reduce the time, costs and other resources required to produce optimum crisps with desirable quality attributes from orangefleshed sweetpotato (OFSP) (ii) understand how chemical components and other quality factors of OFSP crisps changes with frying conditions and (ii) understand that each variety of OFSP requires different combination of frying temperature and time for optimum quality of crisps. OFSP crisps are expected to expand the range of nutritious and attractive snacks available and contribute to improved vitamin A status of consumers. Consumption of OFSP crisps is expected to increase production of the roots and hence improved livelihoods of farmers and other stakeholders along the value chain.