Fried crisps and street-vended chunky fried chips from sweetpotato have been found to be among the products that are capable of increasing utilization of sweetpotato in Nigeria, and also has high commercial potential. Sweetpotato crisps could be marketed as highly nutritious snack foods, particularly the orange-fleshed varieties. However, differences in texture and composition associated with varieties influences process conditions. This study was conducted to determine the optimum frying conditions required for high quality crisps from varieties of sweetpotato. The effect of storage conditions on selected quality attributes of the crisps was also investigated. Three varieties of sweetpotato roots (two orange-fleshed and one yellow-fleshed) were fried into crisps at various combinations of temperature (140-160 °C) and time (3-6 min) as generated by the Central Composite Rotational Design. Fried crisps were analyzed for selected quality attributes (moisture, oil, colour, total carotenoids, sensory attributes) using standard methods. Optimized samples from the three varieties were further analyzed for proximate composition, consumer acceptability and storage stability. Samples were stored in two packaging materials (polyethylene and laminated aluminium foil) at ambient temperature (28±2 °C) for 6 weeks. Stored samples were analyzed for rancidity profile (peroxide value, free fatty acid value, and saponification value), carotenoid retention, and microbiological quality (total viable count, total mould count, Salmonella and Shigella counts). Optimum frying conditions for each variety were: Mothers’ Delight variety; (156.55 °C/3.51 min) which presented moisture content (5.15%), oil content (28.7%), total carotenoid (3866.74 µg/100 g), crispness (7.35), orange colour (7.92), and yellow colour (0.67). King J variety; (140 °C/6.00 min) with moisture (2.48%), oil (24.66%), total carotenoid (3530.52 µg/100 g), crispness (9.85), orange (5.69), yellow (3.81). ‘Anoma fufun’ variety; (150.68/6.00 min) with moisture (23.34%), oil (26.92%), total carotenoid (1934.04 µg/100 g), crispness (9.70), orange (1.79), yellow (7.02). There was a decrease in total carotenoids and an increase in oil rancidity as indicated by the peroxide value, free fatty acid and saponification values for all the sweetpotato varieties and for both packaging materials with Mothers’ Delight having the lowest values. Total viable microbial count also increased with storage period with ‘Anoma funfun’ having the lowest values. Samples stored in laminated Aluminium foil showed higher storage stability for each of the varieties.
Publication Date: March2016
HOW TO CITE
Nasir, S., Olatunde, G., Adebowale, A.R. and Ayelaagbe, I. 2016. Optimization of frying conditions and effect of storage on quality attributes of sweetpotato crisps. Presentation made at the 2016 Marketing, Processing and Utilization Cop Meeting in Tanzania.