The optimum operation conditions of a pumpkin powder extrudate

Abstract

Abstract Pumpkin is rich in nutrition, low in fat and sodium, high in fiber, Vitamin E, I²-carotene, potassium and calcium. It has many kinds of elements and amino acid needed by man. Response surface methodology was used to investigate the optimum operation conditions of a single screw extruder and to analyze the effects of extrusion processing variables, including pumpkin flour contents (10%, 20%, 30%), moisture content (11%, 14%, 17%), and screw speed (250 rpm, 300 rpm, 350 rpm) on characteristics of the corn- pumpkin extrudates. The predicted models were adequate based on the lack of fit test and coefficient of determination obtained. By superimposing individual contour plots of the different responses, regions meeting the optimum conditions were also derived. The moisture content had critical effect on all responses variables. All the characteristic of the corn- pumpkin extrudates evaluated were significantly affected by three process variables. Feed moisture content was the most significant variable on most of characteristics. Individual contour plots of the different responses were overlaid, and regions meeting the optimum bulk density of 0.13~0.15 (g/ml), radial expansion ratio of 7.8~8.4, hardness of 56~64 (N), and water absorption index of 5.4~5.5 (g gel /g dry) were identified at the screw speed of 275~285 rpm, the moisture content level of 12~13 % and the pumpkin powder level of 19~21 %.