Formation of heat-induced protein aggregates in milk as a means to recover the whey protein fraction in cheese manufacture, and potential of heat-treating milk at alkaline pH values in order to keep its rennet coagulation properties. A review

The heat-treatment of cheese milk, or whey, to denature the whey proteins has long been the most applied means of recovering these proteins, either directly in the cheese curd, or as added to the cheese milk prior to renneting. In heat-treated milk, the interaction of the denatured whey proteins with the casein micelles, however, limits the primary phase of the enzymatic reaction, and prevents fusion of the casein micelles. Cheeses containing heat-denatured whey proteins also exhibit excessive moisture, a crumbly and soft texture, and poor meltability. Various technological means to reduce these drawbacks are reviewed. Especially, it is generally accepted that the heat-treatment of skim milk at alkaline pH generates aggregates of denatured whey proteins and κ-casein in the serum phase of milk, rather than on the surface of the casein micelles. As a consequence, the casein micelles are depleted in κ-casein, and free of denatured whey proteins. However, the attempts made to exploit this interesting protein distribution in cheese-making remain scarce, despite their promi-