木聚糖是植物细胞中主要的半纤维素成分，占植物细胞干重的35%，是一种丰富的生物质资源，是自然界中除纤维素之外含量最丰富的多糖。然而自然界中很大一部分木聚糖未被有效利用，造成很大的资源浪费。

木聚糖的结构是一种多聚五碳糖，由β-D-1,4-木糖苷键连接起来，并带有多种取代基。木聚糖部分降解可形成低聚木糖，彻底降解则得到五碳单糖：木糖、阿魏糖、阿拉伯糖等，其中以木糖为主。

Xylan (CAS number: 9014-63-5) is a group of hemicelluloses that are found in plant cell walls and some algae. Xylans are polysaccharides made from units of xylose (a pentose sugar). Xylans are almost as ubiquitous as cellulose in plant cell walls and contain predominantly β-D-xylose units linked as in cellulose.