Effect of somatic cell count on bovine milk protein fractions

Abstract

The objective of this study was to evaluate the influence of somatic cell count (SCC) on the physicochemical properties and protein fractions of milk. Milk was collected and analyzed for somatic cell count, fat, lactose, acidity, total solids, ash, total nitrogen, soluble nitrogen at pH 4.6, and soluble nitrogen in trichloroacetic acid (TCA) 12%. Milk was divided into four groups according to the value of SCC, each constituting a treatment, as follows: Treatment 1 (<300,000 cells/ml), Treatment 2 (300,000 to 750,000 cells/ml), Treatment 3 (750,000-1,000,000 cells/ ml), and Treatment 4 (>1 million cells/ml). The electrophoretic profile of milk was also evaluated using microfluidic electrophoresis for separation and quantification of milk proteins. An increase in the concentration of SCC resulted in a significant increase in the amount of fat, soluble nitrogen and soluble protein (casein) fractions, and a reduction of α-casein, β-casein, and κ-casein. There was a higher proteolytic activity associated with high SCC. Changes in protein fractions of milk caused by high SCC had strong implications regarding the potential of milk as raw material for manufacturing products as the industrial yield of milk is mainly associated with the casein fraction.