Protein emulsifiers, acylation

Another microbial polysaccharide-based emulsifier is Hposan, produced by the yeast Candida lipolytica when grown on hydrocarbons (223). Liposan is apparentiy induced by certain water-immiscible hydrocarbons. It is composed of approximately 83% polysaccharide and 17% protein (224). The polysaccharide portion consists of D-glucose, D-galactose, 2-amino-2-deoxy-D-galactose, and D-galacturonic acid. The presence of fatty acyl groups has not been demonstrated the protein portion may confer some hydrophobic properties on the complex. 

A strain of Acinetobacter calcoaceticus produces an unusual polysaccharide called emulsan. It is a complex polymer comprising about 15% fatty acyl esters and 20% protein. This structure enables it to act as an emulsifying agent, stabilising hydrocarbon/water emulsions at very low concentrations (0.1-1.0%). This property,... 

Similarly, acetylation and succinylation have also been the subject of a few studies. Acylation and alkylation will increase the solubility of proteins, thereby improving their functional properties in general and their emulsifying and foaming properties in particular. 

Figure 48 Effect of pH on the emulsifying activity of various types of modified BSA. Optical density at 550 nm is plotted against pH for diluted solution (pH 7.0, 0.1 M NaCl) and an oil-phase volume fraction of 0.6. The urea-denatured sample was obtained by treating BSA with 0.01 M dithiothreitol for 4 h at 40°C. Acylation was accomplished with 10 1 ratio by weight of anhydride to protein at pH 8-9 for 1 h at 25°C.

In the personal care market, fatty acid derivatives of proteins and amino acids (in particular acyl glutamates) have found broad uses in recent years and are mainly used in mild shower and bath products, mild shampoos, surfactant-based face cleansers, cold-wave preparations and fixatives, baby wash formulations, as well as special emulsifiers for leave-on products. 

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