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Physical Properties of Extrudates Containing Distillers Grains Extruded in a Twin Screw Extruder

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  2007 ASAE Annual Meeting  076213.(doi:10.13031/2013.23526)
Authors:   Nehru Chevanan, Kurt A Rosentrater, Kasiviswanathan Muthukumarappan
Keywords:   Distillers dried grains with solubles, twin screw extrusion, physical properties, aquaculture feed

Extrusion trials were conducted with varying levels of DDGS along with soy flour, corn flour, fish meal, vitamin mix, mineral mix and net protein content adjusted to 28% in a Wenger TX-52 twin screw extruder. The properties of extrudates obtained with experiments conducted in full factorial design with 3 levels of DDGS content, 2 levels of moisture content and 2 levels of screw speed were studied. Increasing the DDGS content from 20% to 60%, resulted in 36.7% decrease in the radial expansion leading to 159%, 61.4% increase in the unit density and bulk density of the extrudates. Increasing the DDGS content resulted in significant increase in the water absorption index (WAI) and significant decrease in the water solubility index (WSI) of the extrudates. Changing the screw speed and moisture content had no effect on the radial expansion ratio, but resulted in significant difference in the bulk density of the extrudates and might be due to longitudinal expansion. Even though changing the moisture content and screw speed had no effect on the WSI of the extrudates, significant difference in the WAI of the extrudates was observed. Color changes in the extrudates was mostly due to color changes in the ingredient components and moisture content of the extrudates and screw speed had least effect on the color of the extrudates.

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