Polysaccharides characterize structurally with long chains of residue of sugar/monosaccharide

Polysaccharides characterize structurally with long chains of residue of sugar/monosaccharide, unlike oligosaccharide that possess 3-10 units’ simple sugars. This reveals structural complexity that exists in macromolecular polysaccharide. They may be linear or branched structural form.
1.1.2. Polysaccharide Sources and Chemical Structural Units
Generally, polysaccharide displayed great diversity in both source and chemical structure (Table 1.1.). Higher organisms such as animals (marine), plants, algae, fungi, and bacteria inherently produce polysaccharide (Shi, 2016). Thus, sources of polysaccharide are very numerous and globally found available. Cellulose, chitin, chitosan, and starch are the dominant polysaccharide biomacromolecules in nature.
Table 1.1: Polysaccharide Various Sources and Structural Units

Name Source Classification Structural Unit/Composition Chain type Bond (Glycoside) Ref.

Starch

Plant e.g. cereals, root and tubers, legumes etc

Neutral or nonionic polysaccharide

D-glucan

Branch
Mostly D-(1:4) and Limited D-(1:6) on branched side
(Lovegrove et al., 2017)

Cellulose
Plant Fiber
Neutral D-glucopyranose ring
Linear
Only D-(1:4)
(Heinze, 2015)

Hemicellulose
Plant e.g. fruit and vegetables

Neutral

D-glucan, D-xylose, and D-galactose in Xyloglucan

Linear

D-(1:4), D-(1:6) linked to D-(1:2)
(Liu et al., 2015; Lovegrove et al., 2017)

Chitin
Animal e.g. marine crustaceans

Cationic
N-acetylglucosamine

Linear

D-(1:4)

(Abdel-Rahman et al., 2015)

Mucilage (Taro)
Plant e.g. Root and tubers
Neutral
Glucose, galactose, mannose, arabinose etc

Gum (Tamarind)

Plant

Nonionic

D-galactoxyloglucan

Branch D-(1:2) and D-(1:6) on branched side chains, and D-(1:4) on glucan backbone
(Nayak and Pal, 2018)

Pectins
Plant e.g. fruit and vegetable
Acidic polysaccharide
D-glucuronic acid
Branch

Fig.1.1. Structural repeats units of some major polysaccharides