The objective of this study was to investigate the influence of K-carrageenan on textural properties of whey protein isolate gels formed by heating at 80°C for 30 min in the pH range from 1-12. In the absence of polysaccharide, very strong and elastic gels were obtained using 10% WPI at pH 7-8. In the presence of Kcarrageenan, the highest shear stress value was observed at pH 6, but strong gels were obtained over a broad pH range up to 11. WPI at a concentration of 3% did not form a self-supporting gel, but significantly enhanced the shear stress values of 0.5% K-carrageenan, particularly at pH 67. A similar enhancing effect of 3% unheated milk protein on K-carrageenan gels at pH 6.7 was also observed. At pH 6-7, where optimal gelation of mixtures was observed, the presence of K-Carrageenan resulted in smaller increases in protein surface hydrophobicity after heating, as determined by the fluorescence probe I-anilinonaphthalene-8-sulfonate. Under these conditions, small angle X-ray scattering studies indicated the formation of a mixed structure gel with attractive interparticle interactions. 0 1998 Canadian Institute of Food Science and Technology. Published by Elsevier Science Ltd. All rights reserved