Abstract
Sweet potato flour and tomato pomace blend were used for the development of extruded products. The response surface methodology was adopted in the experimental design to investigate the effect of feed proportion (5-25% tomato waste powder), moisture content (13-17%), screw speed (275-325 rpm) and barrel temperature (120-140°C) on the quality of the extruded products. Regression equation describing the effect of each variable on the system parameters and product responses were obtained. In all the experiments, the responses were almost equally affected by changes in tomato pomace level, feed moisture, extrusion temperature and screw speed. Increase in barrel temperature results in maximum expansion, minimum hardness and maximum water absorption index (WAI). Higher tomato pomace proportion in feed composition showed minimum expansion, maximum bulk density, minimum WAI and maximum water solubility index (WSI). The compromised optimum condition obtained by numerical optimization were: barrel temperature, 137.01°C, screw speed 343.48 rpm, feed moisture 13.86% and tomato pomace 21.31%. The findings of this study demonstrate the feasibility in development of value added extruded products from tomato pomace and sweet potato flour. Key words: Twin screw extrusion, sweetpotato flour, tomato pomace, response surface methodology.
Highlights
Sweetpotato (Ipomea batatas) known as Shakharkhand, is a very important crop in the developing world
Proximate analysis of sweet potato flour shows that the tomato pomace powder was very high in protein (18.1%)
The increase in water solubility index (WSI) with increasing screw speed was consistent with the results reported for corn meal and corn and wheat extrudates (Jin et al.,1995; Mezreb et al, 2003)
Summary
Sweetpotato (Ipomea batatas) known as Shakharkhand, is a very important crop in the developing world. This tuber is an efficient producer of calories which make significant nutritional contributions to the diet. Apart from being a staple crop for some parts of the world (Papua New Guinea, some parts of the Philippines, Tonga and Solomon Islands), sweetpotato plays a multitude of varied roles in the human diets, being either supplemental or a luxury food. Sweetpotato is one of the seven crops in the world which produce over 135 hundred million metric tons of edible food products in the world annually. China alone produces 80-85% of the total world production (FAO, 1984).
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