Influence of Somatic Cell Count and Breed on Capillary Electrophoretic Protein Profiles of Ewes’ Milk: A Chemometric Study

Abstract 

Bulk tank ewe milk from the Assaf, Castellana, and Churra breeds categorized into 3 somatic cell count (SCC) groups (<500,000; 1,000,000 to 1,500,000; and >2,500,000 cells/mL) was used to investigate changes in chemical composition and capillary electrophoresis protein profiles. The results obtained indicated that breed affected fat, protein, and total solids levels, and differences were also observed for the following milk proteins: β-, β₁-, β₂-, and α_s1-III-casein, α-lactalbumin, and β-lactoglobulin. High SCC affected fat and protein contents and bacterial counts. The level of β₁-, β₂-, and α_s1-I-casein, and α-lactalbumin were significantly lower in milk with SCC scores >2,500,000 cells/mL. A preliminary study of the chemical, microbiological, and electrophoretic data was performed by cluster analysis and principal components analysis. Applying discriminant analysis, it was possible to group the milk samples according to breed and level of SCC, obtaining a prediction of 100 and 97% of the samples, respectively.

Key words: capillary electrophoresis, somatic cell count, casein, whey protein