Genetic factors and dairy-technological valorisation of milk

Among the factors of variation, the genetic ones play a fundamental role in the determination of milk characteristics for cheese making. The genetic factors are more important the more the coagulation is of rennet type. In these conditions, the micelle structure of milk can totally express its intrinsic properties of genetic origin (e.g. polymorphism of caseins). The micelle maintains its structure almost unchanged in all the phases of the whole cheesemaking process, influencing markedly the rheological properties of the curd. Role of the phenotypic combinations of caseins αs1, β, k - In this part of the chapter the phenotypes (electrophoresis in starch-urea gel pH 8.6) of αs1, β and k caseins of 222 individuals' milk samples from Italian Brown cows were determined. The aim was to estimate the effect of the composed phenotype on the physico-chemical and dairytechnological characteristics of milk. The statistical analysis put in evidence significant differences among the 5 considered phenotypes, regarding both the contents of some constituents and the rennet-coagulation characteristics Comparison among genetic types - The aim of this part of the chapter was to study the physico-chemical, chemical and technological characteristics of milk of some genetic types present in the production area of the Parmigiano-Reggiano cheese, in comparison with those of the Italian Friesian cow milk. For this aim, the following four comparisons were carried out: Italian Brown vs Italian Friesian, Jerseyvs Italian Friesian; Ayrshire vs Italian Friesian. The comparison between Italian Brown and Italian Friesian was made at the level of vat milk; while the other comparisons were carried out at the level of herd milk. Dairy technological parameters of the Italian Brown cow milk in relation to types A and B of the β-lactoglobulin - The genetic type of the β-lactoglobulin in individual milk samples from Italian Brown cows was determined. The aim of this part of the chapter was to estimate the relationships between types of β-lactoglobulin and characteristics of milk. The β-lactoglobulin BB milk showed particularly interesting technological parameters, i.e. higher casein content and higher casein number. © 2012 Nova Science Publishers, Inc. All rights reserved.