Response Surface Analysis and Process Optimization of Twin Screw Extrusion Cooking of Potato-Based Snacks

Abstract

The aim of the present study was to optimize the extrusion process for potato-based snacks using response surface modeling approach. A blend of mashed potatoes, rice and chickpea flour was used in the study. The effects of feed moisture, barrel temperature and screw speed on product responses viz. specific mechanical energy (SME), bulk density (BD), water absorption index (WAI), water solubility index (WSI) and hardness was studied using response surface methodology. The blend of potato-rice and chickpea was extruded at different moisture content (12.6–19.4%), screw speed (349–601 rpm) and barrel temperature (116–184C). Feed moisture had significant effect on all product responses, whereas screw speed and barrel temperature, both independent variables, had significant effect on SME, WSI and hardness of the product. Increase in feed moisture reduces SME and WSI and increases BD, WAI and hardness. Increase in screw speed decreases the BD, WAI and hardness of the snacks, whereas increase in barrel temperature decreases the SME, BD, WAI and hardness but increases the WSI. Optimized extrusion parameters for preparation of snacks were 14% moisture, 550 rpm screw speed, 170C temperature. Practical Applications Potatoes are generally processed into flakes, granules and flour by dehydration for using it as raw material for extrusion. Processing costs are very high, so mixing of mashed potatoes with cereal or pulse flour could be an energy-efficient way to use potatoes in extrusion. The consumers are becoming increasingly health conscious and while many admit that pulses are good for them, they are not sure how to use them in diet. There is also a perception that cooking of pulses is difficult and/or time consuming. There is need to find ways to increase consumption of pulses with little extra efforts. This paper explores the optimization of extrusion condition for development of nutritious snacks from potato-chickpea blends.