Cheese production relies on coagulation of milk proteins into a gel matrix after the addition of rennet. Milk that does not coagulate (NC) under optimal conditions affects the manufacturing process, requiring a longer processing time and lowering the cheese yield, which, in turn, has economic effects, according to an announcement from the publishers of the Journal of Dairy Science.
In an article appearing in the Journal of Dairy Science, scientists from Lund University in Sweden studied the protein composition of milk samples with different coagulation properties to learn more about why some milk does not readily coagulate with rennet.
The authors of this study analyzed the protein composition in NC and coagulating milk samples from 616 Swedish Red cows. They reported that the relative concentrations, genetic variants and post-translational modifications of the proteins all contributed to whether rennet could induce coagulation in each sample. The NC milk had higher relative concentrations of alpha-lactalbumin and beta-casein and lower relative concentrations of beta-lactoglobulin and kappa-casein compared with coagulating milk.
"The non-coagulating characteristics of milk relate to protein composition and genetic variants of the milk proteins," said first author Dr. Kajsa Nilsson with Lund University. "Roughly 18% of Swedish Red cows produce non-coagulating milk, which is a high prevalence. Cheese-producing dairies would benefit from eliminating the NC milk from their processes, and breeding could reduce or remove this milk trait."
These results can be used to further understand the mechanisms behind NC milk, develop breeding strategies to reduce this milk trait and limit the use of NC milk for cheese processing, the researchers said.
The Journal of Dairy Science is a publication of the American Dairy Science Assn.