CHAPTER 2 – The Polysaccharide-Water Interface

This chapter describes the polysaccharide–water interface. Water is the universal food solvent, and without hydration, polysaccharides cannot perform as plasticizers, thickeners, texturizers, stabilizers, crystallization inhibitors, and bulking and gelling agents. There are at least four forces in effect at the polysaccharide–water interface namely; van der Waals, ionic, hydrogen bonding, and hydrophobic. The fundamental concept of a polymer molecule in solution is that it consists of a number of segments, each approximating the size of a solvent molecule. The attractive forces at the segment–solvent interface are stronger by far in aqueous polysaccharide dispersion than in a solution of synthetic polymer, and an organic solvent. Hydrocolloidal water is an integral part of the dispersed phase and travels at the same velocity with it. Most polysaccharides affect the mobility and structuring of water beyond the immediate interface to a thickness of several molecular diameters. The reciprocal effect of flowing polysaccharides of surface–water immobilization and structuring is a contribution to distortions from sphericity, and hence to flow birefringence.