The effect of pH and carrageenan concentration on the rheological properties of whey protein gels

Whey proteins and polysaccharides are two gelling biopolymers widely used in the food industry. Gelation of whey protein isolate (WPI), WPI-κ-carrageenan and WPI-λ-carrageenan mixed systems has been investigated. The apparent viscosity of WPI (3%) solutions significantly increased after polysaccharide addition. The highest apparent viscosity was observed at pH 7 and 0.3% κ-carrageenan. The texture properties of WPI and WPI- polysaccharide systems have been investigated in the pH range of 3—10 and κ-carrageenan or λ-carrageenan concentration of 0.1—0.5%. In the absence of polysaccharide, very strong and elastic gels were obtained using 10% WPI at pH 7—8. In the presence of κ-carrageenan, the highest shear stress value was observed at pH 7 and 0.3% polysaccharide concentration. Low κ-carrageenan concentrations have been shown to have a major strengthening effect on WPI gels at pH 3 and 6—8. At pH range of 3—4, the complexes between biopolymers could be formed, however, at pH range of 5—10 the phase separation occurred.