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Food emulsifiers can be manufactured by the esterifi-cation of a polyol such as glycerine or sorbitol with a source of fatty acid. Glycerine can be directly esterified with a fatty acid or, as is usually more economical, glycerine can be transesterified with a fat (glycerolysis). Both procedures will produce a surface active glyceryl monoester such as glyceryl monostearate. The resulting monoester will be surface active because it will possess the fat-loving stearic acid moiety and the water-loving hydroxyl groups of the unesterified polyol carbons within the same molecule (Fig. 1).

Although glyceryl monoesters are the most commonly used surfactants in the food industry and are found naturally occurring in most oil-bearing food (milk, nuts, olives, wheat, etc), other alcohols and aldehydes may be used to supply the hydroxyl groups. When a shortage of glycerine developed during World War II, it was found that a monoester of sorbitol produced by hydrogénation of glucose could be substituted in most cases. Not only were such esters found to be equivalent to those derived from glycerol, they were usually superior. Sorbitol differs from glycerine in that it contains six water-loving hydroxyl groups instead of three and is thus more hydrophilic (Fig. 2).

Other alcohols and aldehydes such as propylene glycol and sucrose may be used to supply the hydrophilic moiety of the surfactant. The hydrophilic character and functional value may be further enhanced by further esterification with organic acids such as lactic, citric, or acetic to produce the diester. The esters can be made even more hydrophilic by ethoxylation (Fig. 3) or by esterification with polymers such as polyglycerol. Because of its amphiphilic character, the surfactant will orient itself to the interface between the lipid and aqueous phase. The more hydrophilic the emul-

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