1. Strategies for Structural Characterization of Polysaccharides

Polysaccharide molecules are constructed by long chains of monosaccharide units bound together via glycosidic linkages. Naturally occurring polysaccharides can be simply classified into four categories according to the source differences: plant polysaccharides, seaweed polysaccharides, animal polysaccharides and microbial polysaccharides (Table 1.1). Each category has its own specific structural features, e.g. most hemicelluloses as plant polysaccharides contain 6 monosaccharides (rhamnose, arabinose, galactose, glucose, xylose and mannose) while some derivatized monosaccharides, e.g. anhydrogalactose, can be found in some seaweeds polysaccharides. The molecular structure offers the most fundamental knowledge for understanding the functional, conformational and physiological properties of polysaccharides, which in turn facilitate their food and non-food applications. However, structural characterization of polysaccharides is a fairly challenging task due to the molecular complexity in terms of monosaccharide composition, glycosidic bonds (linkage patterns), degree of branching/branching position, α- or β-configurations, functional groups, molecular weight and molecular weight distribution.