Protein gels made from cow milk and soymilk can yield products of exceptional value. Transglutaminase (TG) affect rennet-induced gelation of proteins, and improves the functionality of the final products. In this paper, TG and rennet were added to skim milk and soymilk mixtures simultaneously, and the rennet-induced coagulation was studied. Diffusing wave spectroscopy and rheology measurements were used to access the structural changes of the mixtures during renneting. Syneresis analysis and microscopy can give more information for understanding the system.