Why is cellulose insoluble in water? What is cellulose composed of?

Contents of this article

1. Why is cellulose insoluble in water?

2. What does cellulose consist of?

3. What are the three types of cellulase?

Why is cellulose insoluble in water?

There is a structure in plant cellulose called the crystalline region, where adjacent cellulose is tightly connected by hydrogen bonds, and it is difficult for water to enter this region. Even if concentrated acid is used for hydrolysis to destroy the crystalline region, the molecular weight of cellulose is still too large, and the macromolecule itself is difficult to dissolve in water, forming a viscous substance, unless a large amount of water is added to dissolve the macromolecular cellulose.

Generally, when analyzing the composition of wood raw materials, to remove cellulose, concentrated acid hydrolysis is first used and then dilute acid hydrolysis is used. That is, the cellulose crystalline area is first destroyed, and then the cellulose strands are hydrolyzed into monosaccharides one by one.

What is cellulose composed of?

Cellulose is a macromolecular polysaccharide composed of glucose. It is insoluble in water and general organic solvents. It is the main component of plant cell walls. Cellulose is the most abundant natural organic matter in the world, accounting for more than 50% of the carbon content in the plant kingdom. The cellulose content of cotton is close to 100%, which is the purest natural source of cellulose. In general wood, cellulose accounts for 40-50%, and there are 10-30% hemicellulose and 20-30% lignin. In addition, hemp, wheat straw, rice straw, sugarcane bagasse, etc. are all rich sources of cellulose. Cellulose is an important raw material for papermaking. In addition, products made from cellulose are also widely used in plastics, electrical engineering and scientific research equipment. Cellulose (i.e. dietary fiber) in food also plays an important role in human health.

What are the three types of cellulase?

Cellulase is divided into endoglucanase, exoglucanase or cellobiase, and β-glucosidase.

Cellulase is a general term for a group of enzymes that degrade cellulose to produce glucose. It is not a monomeric enzyme, but a multi-component enzyme system that works synergistically. It is a complex enzyme, mainly composed of exo-β-glucanase, endo-β-glucanase and β-glucosidase, as well as highly active xylanase. It acts on cellulose and products derived from cellulose. Microbial cellulase is of great significance in converting insoluble cellulose into glucose and destroying cell walls in fruit and vegetable juices to increase the yield of juice.