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

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