Extraction and structural study of hemicellulose B from tall fescue (Festuca arundinacea) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Chemistry at Massey University

Abstract

1.1 Hemicellulose The structural carbohydrates are mixtures of polysaccharides which together with lignin, constitute the cell wall. Usually they are divided into three fractions: pectic substances, hemicellulose and cellulose.1

Pectins, widely distributed in land plants are characterised by a main chain of 1 – 4 linked galacturonic acid units. They may also contain rhamnose, galactose, xylose, arabinose and fucose in varying amounts. These sugars form part the main chain in some pectins and branch chains in others.2

The pectic triad consists of galacturonan, araban and galactan. Pectic substances occur without exception in all higher plants. It is possible that pectic substances may serve as protective agents for natural rubber particles and may be important food reserve for the plant.3 They are found most abundantly in the primary cell walls and in the intercellular layer.4 [From Introduction]