Effect of extrusion parameters on the capability of water holding and water absorption of texturized soy protein

The Water Holding Capability(WHC) and the Water Absorption Capability(WAC) are very important indexes for the evaluation of texturied soy protein(TSP). The effect of temperature, material moisture, and screw configuration on the WHC and WAC of the TSP were investigated with low temperature defatted soy meal as material using a Brabender twin-screw extruder(DSE-25). The results indicate that, except for the insignificant effect of temperature on the WAC, all indexes have notable effect on WHC and WAC(p＜0.01). The effects of three factors on WHC of TSP are descending from material moisture, screw configuration, to temperature, respectively. The effects of three factors on WAC of TSP are descending from screw configuration, temperature, to material moisture, respectively. The WAC increases with temperature increasing. The WHC and WAC decrease a little after increasing with the material moisture raising. Comparing with the screw configuration with transportation element, the screw configuration with reverse element, kneading block, or tooth block increases the WHC and the WAC of TSP significantly. The variant degree of WAC is more than that of WHC. The important thing of getting high WAC is increasing proposity of TSP.