The effects of extrusion on soy protein isolate solubility [abstract]
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By running soy protein through an extruder at high temperature and pressure, a product can be created that closely resembles meat in its fibrous texture. Thus, much attention has been given to the development of a soy meat analog. Extrusion produces the fibrous texture of meat by denaturing the soy proteins and allowing them to renature with other soy proteins in a fibrous fashion. Since the protein bonds have changed due to extrusion, it was hypothesized that protein solubility would also change as a result of extrusion. To test this hypothesis, samples of both the soy protein isolate (Pro Fam 974) and the extruded soy protein were tested for solubility with a number of different solvents. Samples were mixed with solvent and incubated to allow the two to interact. The samples were then centrifuged, and the supernatant was used to test for protein concentration. The concentration of solubilized protein in supernatant was determined with an assay kit and microplate reader. Results indicated that protein solubility decreased as a result of extrusion. The effectiveness to which each solvent solubilized the protein was similar with both the powder and the extrudate, indicating that the ratio of different bonds in soy protein remained similar in both the powder and the extrudate. Thus, extrusion only decreased the overall solubility of the protein.