Structure and Synthesis of Milk Fat. VIII. Unique Positioning of Palmitic Acid in Milk Fat Triglycerides

Abstract

The preferential esterification of palmitic-acid on the glycerol of various triglyceride types fractionated from goat and cow milk fat was determined by the pancreatic lipase digestion technique. In high molecular weight triglycerides, palmitic-acid showed a definite tendency to be preferentially esterified in the 2-position. As the molecular weight decreased, the palmitic-acid shifted to random distribution; and it was completely reversed in the low molecular weight triglycerides where it was preferentially esterified in the terminal positions of the glycerol. The random distribution of palmitic-acid in a total milk fat sample results from the combination of extremes. The differentiating mechanism which controls the positioning of this acid on the glycerol in milk fat triglycerides may be attributed to the synthetic processes of fat formation.