Ripening characteristics of Cheddar cheese made from bovine milks containing κ-casein AA or BB genetic variants

The ripening characteristics of Cheddar cheeses made from κ-casein AA/β-lactoglobulin AB and κ-casein BB/β- lactoglobulin AB genetic variant milks were investigated over a 274 d period. κ-Casein variant had no significant effect (p > 0.05) on primary and secondary proteolysis, as monitored by nitrogen solubility at pH 4.6 or in 5% phosphotungstic acid, and total levels of free amino acids. Moreover, the profile of proteolysis products was not influenced by κ-casein variant, as indicated by the generally similar peptide molecular weight distribution profiles in cheeses from the κ-casein AA or BB milks throughout the 274 d ripening period. Some amino acids, however, (i.e. methionine, leucine, phenylalanine, histidine and lysine) were significantly (p<0.05) higher in κ-casein BB cheese compared to κ-casein AA cheese at 274 d ripening. κ- casein variant had no significant effect on the rheological (fracture stress and firmness) characteristics or the grading scores awarded for flavour/aroma and body/texture.