Interface stability and copolymers: Application to food systems

Abstract

The stability of oil–water or oil–air emulsions as well as egg white foams is one of the main food-technological problems. On the other hand, proteins are good natural stabilizers and emulsifiers which are widely employed in the technological processing. In this paper we have studied the localization of hydrophobic-polar (HP)-copolymers (which can be viewed as a simplified model for proteins) at a selective solvent–solvent interface. The sequences of the H- and P-species range from regular multiblocks to random and correlated structures. Our approach is based on simple scaling arguments and describes the dependence of the components of the gyration radius of the copolymer chain, perpendicular and parallel to the interface, on the chain length N, the block size M or the “chemical correlation” length ξ , as well as the selectivity parameter χ . The scaling relations differ for the case of weak and strong localization. We implemented a dynamic off-lattice Monte-Carlo model to verify these scaling predictions and for a wide range of chain lengths ( 32 ⩽ N ⩽ 512 ) we find a really good agreement between the simulation results and the theoretical predictions. Some further perspectives and applications are shortly discussed.