THE IMPORTANCE OF MILK PROTEIN VARIANTS F OR CHEESE-MAKING

The B-allels of kappa- and beta-casein and partly of beta-lactoglobuli n produce favourable effects on the processing properties of milk for cheesemaking. As regards both caseins the BB-genotypes occur rarely in bovine populations. This is not attributable to lacking performance, fertility or udder health. Cows with such allels at the mentioned loci have higher protein- and casein contents. If the suitability of milk for cheesemaking is described as rennet coagulation parameter, they le ad to shorter clotting times and higher firmness of the coagulum. In r epeated cheesemaking trials the amount of protein which had passed int o the cheese was higher by 2.7% compared with the genotype AA for kapp a-casein. If the criterion ''suitability of milk for cheesemaking'' sh ould be measured and improved via the parameters of rennet coagulation , increasing the frequency of the BB-genotypes by breeding would be of doubtful value, because only a relatively small part of the variance of the coagulation time and firmness of the coagulum can be explained by the latter and also by the milk protein fraction quantities. On a p ractical scale of cheese factories the effect has to be shown which ha d been observed in cheesemaking trials on a scale of 100 l. If this is possible, increasing the frequency of genotypes in cheese collection areas would be useful. Here, the dairies could pay the insemination co sts for the BB-bulls used. It has to be verified, whether a new rapid method, which, e.g., measures the cheese dust in whey, is more suited to determine the suitability of raw milk for cheesemaking. If possible , the measured parameter shall also be a criterion of breeding.