Proteins as Surfactant Enhancers for Environmental and Industrial Applications

Abstract

Data are presented on the effect of small proteins on the surface activity of synthetic surfactants and their blends as assessed by standard surface science methods. Surface tension of surfactant solutions, interfacial tension between those solutions and water insoluble substrates, and contact angle between these solutions and a solid surface were determined. It is shown that both small individual proteins, such as lysozyme and β-lactoglobulin, as well as proteins in a yeast extract, significantly and predictively reduce critical micelle concentration of multiple widely used surfactants: ionic, non-ionic and amphoteric. Typically, lower minimal interfacial tension could be achieved with a protein synergist, than with the same surfactant in the absence of protein. Examples of industrially important applications of a protein synergist are described. In one of them, the protein accelerates wetting and spreading of surfactant solutions on the hydrophobic surface of green leaves, with concomitant enhancement of the solution uptake by the leaf. In another example, the activity of bacterial lipase, an important industrial enzyme, towards a segregated oil substrate is enhanced by a surfactant-protein synergist blend, as compared to the same surfactant in the absence of a protein synergist