Structural Aspects of Some Functional Polysaccharides

Abstract

Carbohydrate polymers are widespread in nature, and play important roles in all life-stages of the organisms. Biological, physiological and other functions of natural polysaccharides are summarized in Table 1. Although in a nutritional point of view, the most important function of carbohydrate must provide biological fuel, which is reserved in the form of starch or glycogen, some undigestible polysaccharides, either plant hemicelluloses or microbial polysaccharides, have recently attracted attention because of the physiological effect as dietary fibers. In the field of food science and technology, pectic substances in plant cell wall matrix, and a variety of gum exudates, have long been used as emulsion stabilizers, water absorption agents, gelling and thickening agents. In addition, some microbial polysaccharides having unique properties, elaborated extracellularly in abundant amounts, have recently been utilized as a gel-forming agent or a food-packing film. In Table 2 natural polysaccahrides as food hydrocolloids are classified according to their biological sources. Although functionality of individual polysaccharides are closely related to their own molecular shapes, we must first look into the primary structure of the building units, ie. the carbohydrate components, mode of linkages and their sequential arrangements. In this symposium structural correlations with functionality of some plant and microbial polysaccharides, important food hydrocolloids, are discussed.