Contrastive Study of the Foaming Properties of N-Acyl Amino Acid Surfactants with Bovine Serum Albumin and Gelatin.

A detailed study on the foamability, foam stability, foam liquid-carrying capacity, and foam morphology of two N-acyl amino acid surfactants with bovine serum albumin (BSA) and gelatin were performed by foam scanning. The results showed that the foamability of the mixed system increased gradually and then tended to be stable with increasing surfactant concentration. The foamability of the high-concentration BSA system was stronger than that of the low-concentration BSA system. The foamability and foam stability of sodium N-lauroyl phenylpropanoic acid (N-C12P)/BSA were better than those of sodium N-lauroyl propylamino acid (N-C12A)/BSA, and the foamability and foam stability of N-C12A/gelatin was better than those of N-C12P/gelatin. The liquid-carrying capacity of the foam initially increased and then decreased with increasing time, and the maximum liquid-carrying capacity increased with increasing surfactant concentration. When the concentration of the surfactant was 8 mM, the drainage rate of N-C12A/protein was higher than that of N-C12P/protein. The morphology of the bubble gradually changed from spherical to polyhedron and the number of bubbles gradually decreased with time increasing. Differences in surfactant structure and protein type had an important effect on the number and area of foam.