Influence of κ-casein genetic variant on rennet gel microstructure, Cheddar cheesemaking properties and casein micelle size

Cheddar cheese was manufactured on three separate occasions over a two week period from milk collected from two mid-lactation, spring-calving, Holstein-Friesian herds (n = 11) containing similar casein levels, having phenotype AA or BB for κ-casein genetic variant. κ-Casein variant did not significantly (P > 0.05) influence the casein content or gross composition of milk. κ-Casein BB milk had significantly smaller average casein micelle diameter and superior rennet coagulation properties than that of the AA milk. Pilot-scale Cheddar cheesemaking studies showed that the κ-casein BB milk resulted in significantly higher fat recoveries into cheese and higher actual and moisture-adjusted cheese yields. Cheese produced from κ-casein BB variant milk had higher concentrations of fat and lower protein levels than that produced from the AA variant. κ-Casein variant had no significant effect on proteolysis or on the acceptability scores awarded to the cheese.