UNIAXIAL COMPRESSION OF GELS MADE FROM PROTEIN AND KAPPA-CARRAGEENAN

Investigations of gels (18% total solids) made from pea protein isolat es (PPI) or soy protein isolate (SPI) with differing amounts of kappa- carrageenan added showed that the gel strength increased with the conc entration of kappa-carrageenan. When the concentration of kappa-carrag eenan exceeded 0.4%, gels made with PPI were stronger and more stiff t han equivalent gels made with SPI. Addition of kappa-carrageenan stabi lized gels made with PPI towards variations in brittleness (indicated by strain at fracture) with pH. This was not the case when SPI was use d. Preheating (75C, 2 min) suspensions containing protein isolates and kappa-carrageenan before gel formation increased the strength and sti ffness of the final gels, most pronounced when SPI was used. Addition of NaCl (0.5-2%) reduced strength and stiffness of gels, whereas CaCl2 had no influence on gel properties. Mixtures of PPI and SPI proved to be weaker and more brittle than gels made from only SPI of PPI. Resul ts indicate that using proteins of different origin can cause differen ces in gel structure.