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ARS Home » Plains Area » Brookings, South Dakota » Integrated Cropping Systems Research » Research » Publications at this Location » Publication #209193
Title: Effect of Die Dimensions on Extrusion Processing Parameters and Properties of DDGS-Based Aquaculture Feeds

Author
item CHEVANAN, NEHRU - SOUTH DAKOTA STATE UNIV
item MUTHUKUMARAPPAN, K - SOUTH DAKOTA STATE UNIV
item Rosentrater, Kurt

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/22/2007
Publication Date: 9/1/2007
Citation: Chevanan, N., Muthukumarappan, K., Rosentrater, K.A. 2007. Effect of Die Dimensions on Extrusion Processing Parameters and Properties of DDGS-Based Aquaculture Feeds. Cereal Chemistry. 84:389-398.

Interpretive Summary: An ingredient blend containing 40% distillers dried grains with solubles (DDGS), along with soy flour, corn flour, fish meal, whey, mineral and vitamin mix, with a net protein content adjusted to 28% was extruded in a single screw laboratory extruder using 7 different die nozzles. Increasing the moisture content of the ingredient mix from 15 to 25% resulted in a 2.0, 16.0, 16.3, 22.9,18.5, 32.5, and 63.7% decrease, respectively, in bulk density, water solubility index, sinking velocity, L*, b*, mass flow rate, and absolute pressure, as well as an 11.6%, 16.2%, and 7% increase, respectively, in pellet durability, water absorption index, and a*. Increasing the temperature from 100 to 140°C resulted in a 17.0, 5.9, 35.4, 50.6, 28.8, 33.9, and 33.9% decrease, respectively, in unit density, pellet durability, sinking velocity, absolute pressure, specific mechanical energy, torque and apparent viscosity, but a 49.1 and 16.9% increase, respectively, in dough temperature and water absorption index. Increasing the L/D ratio of the die nozzle resulted in an increase in bulk density, L*, a*, and torque, but a decrease in unit density, pellet durability, water absorption index, sinking velocity, b*, mass flow rate, dough temperature and apparent viscosity. Therefore selection of an appropriate die is critical for extrusion processing of DDGS-based blends.

Technical Abstract: The goal of this study was to investigate the effect of die nozzle dimensions, barrel temperature profile, and moisture content on DDGS-based extrudate properties and extruder processing parameters. An ingredient blend containing 40% distillers dried grains with solubles (DDGS), along with soy flour, corn flour, fish meal, whey, mineral and vitamin mix, with a net protein content adjusted to 28% was extruded in a single screw laboratory extruder using 7 different die nozzles. Increasing the moisture content of the ingredient mix from 15 to 25% resulted in a 2.0, 16.0, 16.3, 22.9,18.5, 32.5, and 63.7% decrease, respectively, in bulk density, water solubility index, sinking velocity, L*, b*, mass flow rate, and absolute pressure, as well as an 11.6%, 16.2%, and 7% increase, respectively, in pellet durability, water absorption index, and a*. Increasing the temperature from 100 to 140°C resulted in a 17.0, 5.9, 35.4, 50.6, 28.8, 33.9, and 33.9% decrease, respectively, in unit density, pellet durability, sinking velocity, absolute pressure, specific mechanical energy, torque and apparent viscosity, but a 49.1 and 16.9% increase, respectively, in dough temperature and water absorption index. Increasing the L/D ratio of the die nozzle resulted in an increase in bulk density, L*, a*, and torque, but a decrease in unit density, pellet durability, water absorption index, sinking velocity, b*, mass flow rate, dough temperature and apparent viscosity. As demonstrated in this study, the selection of an appropriate die geometry, in addition to the selection of suitable temperature and moisture content levels, are critical for producing DDGS-based extrudates with optimum properties.