Polysaccharide Hydrocolloids of Commerce

Abstract

This chapter discusses the polysaccharide hydrocolloids of commerce. Following the modern trend, this name is condensed to “polysacolloids.” Polysacolloids abound in Nature as structural, storage, vascular, or functional components of plant and animal tissues, but only a limited number, all from plant sources, are of commercial importance. Most polysacolloids are complex mixtures, which are difficult to separate. Intermolecular linkages involve not only other polymers but low molecular-weight substances as well. Precipitations and solvent separations that are clean-cut for mixtures of compounds in the low molecular-weight range are usually ineffective in the presence of polymers. In addition, there is no criterion of purity for the recovered parts to be analyzed. Polysacolloids find use because of the physical properties they exhibit when they are dissolved and when they are dried. Sols of polysacolloids are viscous, and have rheological properties that help provide stability in suspensions, emulsions, and foams. These same rheological properties have subjective attributes, which provide pleasure to the sight and feel. Sols of some of the polysacolloids can be transformed into rigid structures called gels, some of which have thermal sol-gel reversibility, whereas others require chemical action .