Effects of genetic variants of κ-casein and β-lactoglobulin on cheesemaking

Abstract

SUMMARYThe effects of κ-casein and β-lactoglobulin (β-lg) genetic variants on cheesemaking were examined in two laboratory scale experiments. Variants of κ-casein had highly significant (P < 0·001) effects on milk citrate content (A > B) and rennet clotting time (A > B). When curds were cut at constant firmness there were only minor effects of κ-casein variants on milk component recoveries and cheese yield and composition. A tendency to higher fat recoveries from milks containing κ-casein B was reflected in significantly (P < 0·05) higher fat contents in cheese after 3·5 months of ripening. Genetic variants of βlg had highly significant (P < 0·001) effects on casein number (B > AB > A) and protein recoveries (B > AB > A) and significant (P < 0·05) effects on yield of cheese dry matter (B > AB > A). Green (unripened) cheeses made from the different milks also differed in fat, protein and moisture contents, probably in part due to differences in fat/casein ratios of the cheesemilks. The compositional differences were reflected in differences in the extent of proteolysis during ripening (A > AB > B). In the experiment with β-lg genetic variants the effect of time of cold storage of the cheesemilk was also investigated. No differences were found in milk composition and component recoveries or cheese yield, composition and quality when milks were cold-stored for 24, 48 or 120 h before cheesemaking.