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 .
