The composition of milk fat

J Dairy Sci. 1991 Sep;74(9):3228-43. doi: 10.3168/jds.S0022-0302(91)78509-3.


Bovine milk contains about 3.5 to 5% total lipid, existing as emulsified globules 2 to 4 microns in diameter and coated with a membrane derived from the secreting cell. In homogenized milk, the coat is mostly casein. About 98% or more of the lipid is triacylglycerol, which is found in the globule. Phospholipids are about .5 to 1% of total lipids, and sterols are .2 to .5%. These are mostly located in the globule membrane. Cholesterol is the major sterol at 10 to 20 mg/dl. Data are presented on the membrane and the emulsion. Bovine milk contains substantial quantities of C4:0 to C10:0, about 2% each of C18:2 and trans-C18:1, and almost no other long-chain polyunsaturated fatty acids. The fatty acid composition is not altered by ordinary changes in diet. The triacylglycerol structure is unique, with much of the C4:0 to C10:0 at sn-3. The effects of milk cholesterol and fatty acids on human blood cholesterol levels and nonnutritive roles of some microlipids are discussed.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Animals
  • Cattle
  • Cholesterol / analysis
  • Emulsions
  • Fatty Acids / analysis
  • Lipids / chemistry*
  • Milk / analysis*
  • Phospholipids / analysis
  • Sterols / analysis
  • Triglycerides / analysis


  • Emulsions
  • Fatty Acids
  • Lipids
  • Phospholipids
  • Sterols
  • Triglycerides
  • Cholesterol