IV.2 - Influence of sheep AA, CC and DD αs1-casein variants on milk composition and cheese yield

This paper focuses on the influence of sheep AA, CC and DD α s1 -casein variants on milk composition and cheese yield. Cheesemaking trials have been carried out by a cheesemaking pilot plant. The processed bulk milk was collected from three groups of ewes each carrying AA, CC and DD α s1 -casein variants, respectively. Results indicated that the milk containing CC α s1 -casein was significantly different (P<0.01) with regard to total protein (+5.22% and +11.3% versus AA and DD milk, respectively), casein content (+4.42% and +11.5% versus AA and DD milk, respectively). The milk was also significantly different (P<0.05) for dry matter and fat content, whereas no significant differences in whey proteins and NPN levels among the different groups were reported. The protein-to-fat ratio was higher in CC milk and intermediate in AA milk. The losses of fat and protein in the whey were significantly different: greater in whey from CC processed milk. Significant differences in cheese yield were detected among milks with different variant. The average gross yield was higher (P<0.01) in CC milk (+7.95% and + 9.43% versus AA and DD milk, respectively). The moisture adjusted yield differed significantly (P<0.01) for CC and DD milk. For this parameter the differences among the three groups were lower than gross yield because the 24 h old cheeses were different in dry matter content. Dry matter recovery rate was also better (P<0.05) for CC milk while fat recovery rate was worse than AA and DD milk.