Effect of microwave-assisted pre-drying and deep-fat-frying conditions on some quality attributes of orange fleshed sweetpotato chips

Abstract

The effect of microwave-assisted drying (MAD) and deep-fat frying conditions on moisture and oil contents, hardness, chewiness, and colour (L*, a*, and b*) attributes of orange-flesh-sweet-potato (OFSP) chips were studied. A response surface methodology based on Box–Behnken design was used to optimize the effect of weight loss (10 – 20%) during MAD, frying temperature (150 – 170 °C), and frying time (1 – 3 min) on moisture, oil contents, hardness, chewiness, and colour of the chips. Models were generated showing the relationship between independent and response variables. The process variables had significant effects on the investigated responses. Frying temperature had a significant (p<0.05) effect on the oil, moisture contents, and chewiness. Weight loss had a significant (p<0.05) effect on hardness, and moisture content, while frying time had a significant (p<0.05) effect on hardness, chewiness, and moisture content. Furthermore, frying temperature had significant (p<0.05) interactive effect on moisture content and chewiness. The desirability index was 0.580 and the optimum conditions obtained were percentage weight loss of 10.51%, a frying temperature of 168. 68 °C and frying time of 2.78 min. In these conditions, OFSP chips of acceptable moisture and oil contents with desirable colour and textural parameters were obtained.