The chemical composition and physical properties of fractions of milk fat obtained by a commercial fractionation process

Abstract

SummarySamples of liquid and solid fractions obtained by a commercial process from anhydrous milk fat of softening point (S.P.) 33·5–34°C had S.P. values of 22–23°C and 36–38°C respectively.Determinations of fatty acid composition by GLC showed that unsaturated and short chain fatty acids were present in increased concentration in the liquid fraction (average 37·8 and 12·4% as compared with 35·1 and 10·8% in the original milk fat) and long chain saturated acids in the solid fraction (average 57·8 as compared with 53·8%). There was some concentration of carotene and vitamin A, and to a lesser extent of cholesterol, in the liquid fraction.Crystallization and melting curves determined by a differential scanning calorimeter (DSC) showed that while the liquid fraction was completely melted at 25°C, the solid fraction contained an increased proportion of fat melting between 30 and 40°C. In addition to these high melting triglycerides the solid fraction also contained some 65% of fat in the liquid phase at the original crystallization temperature of 25°C.