Residence Time Distribution of Soy Protein Isolate and Corn Flour Feed Mix in a Twin-Screw Extruder.

Yu, L., Meng, Y., Ramaswamy, H.S., and Boye, J.I. (2014). "Residence Time Distribution of Soy Protein Isolate and Corn Flour Feed Mix in a Twin-Screw Extruder.", Journal of Food Processing and Preservation, 38(1), pp. 573-584. doi : 10.1111/jfpp.12005  Access to full text

Abstract

The residence time distribution (RTD) of soy protein isolate (SPI) and corn flour mixture through a twin-screw extruder under different conditions was evaluated. A full-factorial design of experiments was used to select the variables at different levels. The feed mixture was prepared by blending corn flour and SPI in the ratio of 4:1 (20% SPI content). The effect of screw speed (75, 100 and 125rpm), feed mixture moisture content (25, 30 and 35%) and die diameter (3 and 5mm) were investigated. All factors were found to have a significant (P<0.05) effect on the mean resident time and its variance (square of standard deviation). Higher screw speed, higher initial moisture content and larger die diameter resulted in a shorter mean residence time. Two conventional flow models were used to represent the RTD profile in the extruder - the frequency model (F-distribution) and the cumulative RTD model (E distribution). The parameters of these models - the half-concentration internal age and particle accumulation rate – were determined by a nonlinear regression. The parameters of these models were responsive and related to process variables and both F- and E-distributions were well predicted.

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