Introduction

Xylans are a group of pentosans (5-carbon sugar containing molecules) composed of xylose residues (individual molecules) In woods, and straws, xylans give structural strength. Note that although some sugars in plants play structural roles, animals can eat these plants in order to obtain energy. However, certain animals do not have enzymes to digest certain sugars. For example, humans cannot digest cellulose, a structural sugar found in plants, because we do not produce the correct intestinal enzymes. However, ruminants, such as cows and sheep produce the necessary enzymes and can thus use cellulose as an energy source. Any cellulose we obtain from our diet is not fully digested and acts as roughage, or fibre. We also call these non-starch polysaccharides.