Engineering Analysis of Soy Dough Rheology in Extrusion

Abstract

Effects of moisture level, temperature and shear rate on the rheological properties of defatted soy dough during extrusion were studied on a Brabender laboratory extruder. Entrance pressure loss through the extruder capillary die as well as viscosity of the cooked and compressed soy dough were expressed as a function of added moisture, shear rate and temperature through multiple regression analysis. Process conditions involved in this study were (a) temperature from 100 to 160°C; (b) added moisture from 22 to 32% and (c) shear rate from 50 to 10,500 sec−1. Data were collected at steady state. It was found that in the shear rate range of 50 to 1,000 sec−1 and temperature range of 100 to 160°C the viscosity of the cooked and compressed soy dough with 32%, 25% and 22% added moisture ranged from 10,000 to 500 poise and 20,000 to 200 poise and 20,000 to 1,000 poise respectively.

Effects of Processing Conditions on Single Screw Extrusion of Feed Ingredients Containing DDGS

“…Furthermore, viscosity typically decreases as processing temperature increases Kokini et al 1992). These behaviors occur due to structural changes in the food dough (i.e., unfolding of molecules and material structures) during processing (Harmann and Harper 1974;Jao et al 1978;Luxenburg et al 1985).…”

The Effect of Extrusion Operating Conditions on the Apparent Viscosity and the Properties of Extrudates in Twin-Screw Extrusion Cooking of Maize Grits

“…The end pressure effects were corrected by varying the length to diameter ratio of the die (from 9.5 to 15.5), at constant extusion conditions. The detailed procedure of calculations can be found in Jao et al (27).…”

“…A general model of extrudate expansion is developed including the radial, longitudinal and volumetric expansion (21). The apparent melt viscosity of starch-based materials have been extensively investigated (7,(27)(28)(29)(30)(31)(32)(33). The apparent viscosity has been found to be dependent on melt temperature, flow shear rate, material composition such as fat and moisture content, and extrusion processing history.…”

Measurement of rheological and ultrasonic properties of food and synthetic polymer melts

“…Various authors have used such equipment to study food dough and polymer rheology [1][2][3]. Instead of a piston-driven rheometer, other workers have used screw extruders to feed capillary dies of various length to diameter ratios [4][5][6][7][8].…”