Effects of Milk Composition and Genetic Polymorphism on Cheese Composition

Cheese was manufactured for 14 mo under controlled laboratory conditions from 291 lots of milk originating from 31 Holstein cows of different phenotypes for β-casein, κ-casein, and β-lactoglobulin. Cheese samples from each lot were assayed for total solids, fat, and protein. Milk was analyzed for total solids, fat, protein, casein, lactose, urea nitrogen, nonprotein nitrogen, citric acid, and somatic cell count. Whey was assayed for total solids, fat, and protein. Least squares analysis of data indicated that milk from cows of β-casein A1A1 phenotype produced cheese averaging 62.45, 33.54, and 24.17% total solids, fat, and protein compared with 62.73, 33.17, and 24.14% for milk from A1A2 phenotype. Comparable figures for κ-casein were 62.57, 33.64, 24.07%; 62.49, 33.51, 23.83%; and 62.71, 32.92, 24.56% for phenotypes AA, AB, and BB, respectively. Losses of milk components were lower in the whey derived from β-lactoglobulin BB than from β-lactoglobulin AA and AB phenotype milk. An increase of 1% milk fat was accompanied by changes in cheese fat and protein of 3.84% and −1.89%, respectively. Comparable figures for a percentage unit increase in milk casein were −1.55 and .79%.