ARS | Publication request: MODELING EXTRUSION PROCESSING OF AQUACULTURE FEED INCORPORATING DISTILLERS GRAINS

Submitted to: Symposium Proceedings
Publication Type: Proceedings/Symposium
Publication Acceptance Date: May 12, 2006
Publication Date: July 12, 2006
Citation: Chevanan, N., Muthukumarappan, K., Rosentrater, K.A., Julson, J. 2006. Modeling extrusion processing of aquaculture feed incorporating distillers grains. 2006 ASABE Annual International Meeting, Portland OR, July 9-12, 2006.

Technical Abstract: Three ingredient blends containing 20, 30, and 40% Distillers Dried Grains with Solubles (DDGS), with a net protein adjusted to 28% were prepared. Extrusion studies were conducted at 3 levels of moisture content, 3 levels of barrel temperature profile, and 5 levels of screw speed in a single screw extruder. The torque requirement, specific mechanical energy (SME) consumption, and apparent viscosity decreased as screw speed increased. At higher temperatures in the barrel and die, the viscosity of the dough was lower, leading to lower torque and specific mechanical energy requirements. Viscosity modeling resulted in a positive coefficient for moisture content, while the measured apparent viscosity did not show an increasing trend as the moisture content of the ingredient mix was increased from 15% (wb) to 25% (wb). The coefficient for DDGS in the viscosity model was found to be positive and the measured apparent viscosity increased as the DDGS content was increased. Increasing the DDGS content resulted in a higher mass flow rate and decreased absolute pressure inside the die. The coefficient for the DDGS in the viscosity model was much higher compared to the coefficient for moisture content, indicating that the viscosity can be controlled readily by adjusting the level of DDGS. Modeling of the viscosity of dough in the barrel resulted in flow behavior index `n¿ value <1 for reference viscosity values between 0 and 3. The regression coefficient value obtained between the apparent viscosity calculated by the concentric cylinder method and the viscosity calculated by the resulting model equation was found to be over 0.99.