Besides cellulose , there are hemicellulose and lignin .

除了纤维素，还有半纤维素和木质素。

The hemicellulose separates into its chief building block , a sugar called xylose , which can then be washed away with hot water .

半纤维素被分割成主要的建筑块一种称为木糖的糖，然后木糖被热水冲洗走。

Grass , trees and other biomass feedstocks consist of a mixture of cellulose , hemicellulose and lignin , a tough material that helps plants keep their shape .

草、树和其他生物基原料是由纤维素、半纤维素以及维持植物外形的木质素组合而成的。

Making ethanol from cellulosic feedstocks is harder still , however , since it involves breaking down the tough , winding chains of cellulose and hemicellulose from the walls of plant cells to liberate the sugars .

从纤维原料中制造乙醇则更加困难，因为牵涉到催化坚硬的纤维素和半纤维素旋圈，让糖从植物细胞壁中释放出来。