Effect of κ-casein B relative content in bulk milk κ-casein on Montasio, Asiago, and Caciotta cheese yield using milk of similar protein composition

The aim of this study was to investigate the effect exerted by the relative content of kappa-casein (kappa-CN) B in bulk milk kappa-CN on coagulation properties and cheese yield of 3 Italian cheese varieties (Montasio, Asiago, and Caciotta). Twenty-four cheese-making experiments were carried out in 2 industrial and 1 small-scale dairy plant. Detailed protein composition of bulk milk of 380 herds providing milk to these dairies was analyzed by reversed-phase HPLC. To obtain 2 experimental milks differing in the relative content of kappa-CN B in kappa-CN, herds were selected on the basis of bulk milk protein composition and relative content of kappa-CN genetic variants. Milk was collected and processed separately for the 2 groups of selected herds. A difference of 20% in the relative content of kappa-CN B in kappa-CN was obtained for the 2 experimental milks for Montasio and a difference of 15% for Asiago and Caciotta. The 2 experimental milks were of similar protein and CN content, casein number, pH; CN composition, and beta-CN genetic composition. For each cheese-making trial, amounts of milk, ranging from 2,000 to 6,000 kg, were manufactured. Each vat contained milk collected at least from 4 dairy herds. Cheese yield after brining and at the end of the aging was recorded. Milk with a greater proportion of kappa-CN B in kappa-CN (HIGHB) exhibited similar coagulation properties and greater cheese yield compared with milk with a lower proportion of kappa-CN B in kappa-CN (LOWB). The increased cheese yield observed for HIGHB when manufacturing Montasio cheese was ascribed to a greater fat content compared with LOWB. The probability of HIGHB giving a cheese yield 5% greater than that of LOWB ranged from 51 to 67% for Montasio cheese, but was less than 21% for Asiago and Caciotta cheeses. Variation in relative content of kappa-CN B in kappa-CN content did not relevantly affect industrial cheese yield when milks of similar CN composition were processed. An indirect effect due to the increased kappa-CN content of kappa-CN B milk is thought to explain the favorable effects of kappa-CN B on cheese yield reported in the literature.