Comparative study of the protein fraction of goat milk from the Indigenous Greek breed and from international breeds

Individual goat milk samples, taken from animals of the Indigenous Greek breed and from the international breeds Saanen and Alpine, were studied by RP-HPLC regarding the qualitative and quantitative characteristics of their proteins. Thirty-two samples from the Indigenous Greek breed and 17 from the international breeds were characterised further by RP-HPLC/ESI-MS. The mean total protein content of the milk samples from the Greek breed was higher 38.8 g/l, compared to 31.9 g/l of those from international breeds, due to the great difference between their mean alpha sl-Cn contents (6.90 and 3.02 g/l, respectively). In the milk samples of the Greek breed, the strong alpha sl-Cn variants B3, B4 and As/B1 predominated, whereas in the milk samples from international breeds the medium variant E and the defectives F and null predominated. Variant A of alpha s2-Cn followed by variant C and the kappa-Cn D (former B) were the most abundant in both groups. alpha s2-Cn F and the rare kappa-Cn variant C/B were observed in the milk samples from the Greek breed. The beta-caseins A and C were present in both groups of samples. Finally, the level of phosphorylation of the different genotypes is showed. (C) 2007 Elsevier Ltd. All rights reserved.