Physical Equilibria: Lipid Phase

Abstract

Milk contains a complex mixture of lipids in terms of fatty acid composition and in the distribution of these acids in neutral lipids and phos-phoglycerides. In addition, there are major variations among species in both the amount and fatty acid composition of milk lipids. In terms of amount, certain seals and whales produce milk which is over 50% lipid by weight, while the milk of certain rhinoceri contains less than O.1% lipid (Jenness 1974). As discussed by Jenness in this volume (Chapter 1), relative to the number of mammalian species extant, we have but a rudimentary knowledge of the composition of milk. Most present-day knowledge of the organization of milk lipids has come from studies of milk from cows, although in recent years there has been increased interest in extending these studies to other species, particularly Homo sapiens (Jensen et al. 1980; Blanc 1981). Most of the discussion in this chapter will deal with bovine milk lipids. Where instructive, comparisons with other species will be made.