Effect of genetic polymorphism of milk proteins on rheology of chymosin-induced milk gels

uIndividual milk samples from 121 cows in mid lactation of the Swedish Red and Swedish Holstein breeds with known protein genotypes of beta- and kappa-casein and beta-lactoglobulin were analysed. Chromatographically pure chymosin was added to skim milk and rheological properties of the gels were measured using a Bohlin VOR Rheometer. Coagulation time (CT) and curd firmness after 25 min (G'(25)) were registered for each sample. The B allele of kappa-casein was associated with improved coagulating properties of milk, whereas the E allele showed a negative effect on these traits. The beta-casein A(2)A(2) genotype was associated with inferior milk coagulation characteristics. Total protein concentration of milk was positively associated with curd firmness, but showed no association with milk coagulation time. (c) 2006 Elsevier Ltd. All rights reserved.