Rheology and structure of milk protein gels

Recent studies on gel formation and rheology of milk gels are reviewed. A distinction is made between gels formed by aggregated casein, gels of 'pure' whey proteins and gels in which both casein and whey proteins contribute to their properties. For casein-whey protein mixtures, it has been shown that both the fraction whey protein aggregated with the casein particles and whey protein aggregates dispersed in the continuous phase have a large impact on the structural and mechanical properties of heated and acidified milk gels. The availability of site-directed mutants of beta-lactoglobulin for aggregation and denaturation studies is an important development in the field of whey protein gelation. Besides cold gelation by whey proteins has received much attention. Major recent advances: During recent years, the dynamic character of casein gels has been much better appreciated. For gels of heated milk, the important role of the whey protein that stays dispersed in the continuous phase after heating has been shown for acid-induced gel formation. Some advances has been made in understanding the molecular details of the protein-protein interactions. (C) 2004 Elsevier Ltd. All rights reserved.