COMPOSITE MILK PROTEIN PHENOTYPES IN RELATION TO COMPOSITION AND CHEESE-MAKING PROPERTIES OF MILK

The effects of composite milk protein phenotypes on the composition an d cheesemaking properties of milk were studied. Pooled milks from 12 s elected groups of Brown cattle with particular phenotype combinations of beta-casein (A(2)A(2), A(2)B), kappa-casein (AA, AB, BE) and beta-l actoglobulin (AA, BE) were investigated. alpha(s1)-Cn BE was common to all animals. Milk collection and cheesemaking trials on a pilot scale were repeated four times during winter 1993. The interaction between all three gene loci (beta-Cn, kappa-Cn, beta-Lg) was found to be highl y significant (P < 0.001) for the contents of total protein, casein, w hey protein and fat. The casein number was 0-4% (absolute) higher for beta-Lg BE milk than for beta-Lg AA milk. The relative amount of kappa -casein consistently increased from kappa-Cn AA to kappa-Cn BE. The lo sses of fat and curd fines in the whey and moisture-adjusted cheese yi eld were also affected by the genotype combinations. Recovery of milk solids was 3% higher for beta-Cn A(2)B milk than for beta-Cn A(2)A(2) milk (P=0.010). (C) 1997 Elsevier Science Ltd. All rights reserved.