Protein-Lipid Interactions and their Relation to the Physical-Chemical Stability of Concentrated Milk. A Review

Abstract

We have considered the types of bonding forces responsible for lipid-lipid and protein-lipid interactions. These include (a) nonpolar bonds, which function at short distances and are usually referred to as van der Waal's forces; (b) polar bonds, resulting from an unsystematical sharing of electrons, which are fairly strong forces and often function through the hydrogen bond; and (c) charged structures, which serve as proton donors or acceptors and attract oppositely charged groups at considerable distances. The native membrane represents the principal lipid-protein complex in normal milk. It is composed of at least two proteins, phospholipids, a high-melting triglyceride fraction, cholesterol, free fatty acids, mono-diglycerides, cholesterol esters, carotene, and other minor lipid fractions. The normal membrane material is dislodged from its interfacial surface by agitation, heat treatment, homogenization, vacuum concentration, freezing, and drying. Its rearrangement at the interfacial surface increases the susceptibility of milk to photo-activation and decreases its susceptibility to metallic-catalyzed oxidative deterioration. Milk fat can be resurfaced with the proteins of the skimmilk phase, but they are less stable than the native emulsion. Oxidative deterioration of the lipids enhances the formation of insoluble lipid-lipid and/or protein complexes. © 1962, American Dairy Science Association. All rights reserved.