Protein rich extruded snack foods using hydrolyzed proteins

Abstract

The effects of the degree of protein hydrolysis and feed concentration of protein were tested on corn meal extrudates using a single screw extrusion system. Four different concentrations of whey protein isolate (0%, 5%, 10%, and 15%) with differing levels of hydrolysis (0%, 4.5%, 10.0%, and 14.9%) were mixed with corn meal and then extruded. Samples of the extrudates were tested for breaking strength, apparent density, true powder density, expansion ratios, and porosity. It was found that extrudates containing the hydrolyzed proteins had physical characteristics similar to those of the 100% corn meal samples. Many of the undesirable effects of adding unhydrolyzed protein to extrusion feed mixtures either did not occur or occurred to a lesser extent when partially hydrolyzed proteins were added. It was also found that as the degree of protein hydrolysis and as the protein concentration of the extrusion feed mixture increased the breaking strength and the apparent density of the extrudate decreased to values that were lower than the extrudate of the control corn meal. Extrusion runs that utilized hydrolyzed and unhydrolyzed forms of the isolated soy proteins produced similar results which suggests that changes in the physical properties of protein hydrolysate fortified corn meal extrudates are independent of the protein source.