Functional Properties of Biosurfactants in Combination with Food Proteins

Surfactants are amphiphilic surfac- active molecules that are used in a wide range of consumer products (personal care, detergents, foods, cosmetics) for their ability to adsorb to and to stabilize fluid-fluid (oil-water and air-water) interfaces. Current surfactants are often synthesized from petrochemical feedstock or obtained from non-sustainable biological feedstock (e.g. palm oil). There is growing interest in replacing chemical surfactants with those made by microbial fermentation from bacteria or yeast (so-called biosurfactants). Examples of these include glycol lipids such as rhamnolipids and sophorolipids. Although glycolipid biosurfactants are being introduced into some products, particularly detergents, their use in food is held back by a relative lack of information on how they perform I these systems compared to chemical surfactants. In addition, glycolipid biosurfactants are often produced from engineered bacteria to increase yield to the point where the process is economically viable.

I will present in this talk some of our results on a comparison of the surface activity and emulsification properties of rhamnolipid and a range of sophorolipid biosurfactants. The properties of the biosurfactants will be compared to conventional surfactants and differences will be explained in terms of the expected self-association behavior in solution and the expected conformation they adopt at fluid interfaces.