Stability of Milk Fat Emulsions. II. Influence of Emulsifier Structure, Sodium Caseinate, and Nonfat Milk Solids

Abstract

The physical stability of model oil-in-water emulsions, containing 25% milk fat and 0 to 2.0% emulsifier in the fat, was used to determine the efficiency of 37 emulsifiers from the following chemical classes: monoglycerides, acid-modified monoglycerides, phospholipids, sorbitol partial esters, polyoxyethylene sorbitan fatty acid esters, polyglycerol esters, and propylene glycol partial esters. Stability was related to emulsifier structure and concentration. Differences in fatty acid side chains or in melting point of the milk fat had less important effects. In a comparison of purified phospholipid classes, phosphatidyl serine and phosphatidyl inositol gave emulsions superior in stability to those prepared with phosphatidyl ethanolamine, phosphatidyl choline or sphingomyelin. The more efficient commercial emulsifiers were sodium stearoyl-2-lactylate, soybean phospholipids, and polyoxyethylene sorbitan fatty acid esters. These were used to prepare similar emulsions containing, in addition, various amounts of sodium caseinate or nonfat milk solids. Stability was related to specific emulsifier, its concentration, and to sodium caseinate or nonfat solids. When interference occurred between emulsifier and sodium caseinate or solids, stability was reduced. There was no significant difference in emulsion stability regardless of whether soybean lecithin was dispersed in the fat or in the aqueous phase before emulsification. © 1975, American Dairy Science Association. All rights reserved.