Pasting and Extrusion Properties of Mixed Carbohydrate and Whey Protein Isolate Matrices

Mixed systems of whey protein isolate (WPI) or texturized WPI and different starches may form weak or strong gel pastes or rigid matrices depending on interactions. The paste viscoelasticity of starches from amioca, barley, cornstarch, Hylon VII, plantain and pea starch, mixed with whey protein isolate or textured WPI at the concentrations of 75/25, 50/50 or 25/75 wt% was determined using a Rapid Visco Analyzer. Peak paste ranged from plantain (5.33 Pa·s), amioca (4.14 Pa·s), cornstarch (3.65 Pa·s), barley (2.61 Pa·s), Hylon VII and pea starch (10 mPa·s). The presence of whey proteins reduced paste viscosity and extrusion expansion, but reduced hardness and improved fracturability. Moisture content was a stronger determinant of paste properties and of the denatured state of the whey protein isolate. Practical Applications Foods may contain starches from different carbohydrate and protein sources. Food formulators sometimes combine different proteins and carbohydrate for desired textural benefits. Our study shows that some protein–starch interaction synergies depend on the source of starch and the amount of protein isolate admixed. This knowledge is useful to manufacturers who may seek to enhance food texture by blending different proteins.