Incorporation of whey proteins into cheese curd by using transglutaminase.

A Ca(2+)-independent microbial TGase (transglutaminase) isolated from Streptoverticillium mobaraense was used to obtain whey protein containing novel dairy products. We evaluated the difference both in the curd formation time as well as in the hardness and deformability of the cheese obtained from cow's milk in the presence or absence of the enzyme. The results of our experiments showed that the milk coagulation time was dependent on the step in cheese manufacture at which TGase was added. We analysed the deformability and the hardness of the dairy products obtained either by adding both TGase and the milk-clotting enzyme to the milk sample at the same time or by adding TGase after treating the milk sample for 30 min with the clotting enzyme and cutting the obtained coagulum. TGase treatment conferred a strongly decreased protein content to derived whey. Moreover, when further amounts of whey were added to the milk during the manufacturing process in the presence of TGase, whey-protein-enriched dairy products could also be obtained. Our findings may lead to new biotechnologies for the re-utilization of by-products from dairy plants and contribute to reduction of environmental pollution from whey-protein disposal.