What is the chemical composition of cellulose?

Many of the foods we eat contain cellulose. Supplementing cellulose has many benefits to human health. For example, it can assist in the treatment of diabetes and prevent coronary heart disease. Many people now have high blood pressure, and supplementing cellulose has a good blood pressure lowering effect. It is worth mentioning that supplementing cellulose also has the effect of weight loss, but many people do not know what ingredients cellulose contains, so the following is a detailed introduction to relevant professional knowledge about cellulose.

What is the chemical composition of cellulose?

The chemical composition of cellulose is (C6H10O5)n.

Cellulose is a macromolecular polysaccharide composed of glucose. Insoluble in water and general organic solvents. It is the main component of plant cell walls. Cellulose is the most widely distributed and abundant polysaccharide in nature, accounting for more than 50% of the carbon content in the plant kingdom. Cotton has a cellulose content of nearly 100% and is the purest natural source of cellulose. In general wood, cellulose accounts for 40-50%, with 10-30% hemicellulose and 20-30% lignin.

Cellulose is the main structural component of plant cell walls and is usually combined with hemicellulose, pectin and lignin. The way and degree of combination have a great influence on the texture of plant-based foods. The changes in texture of plants during maturity and ripening are caused by changes in pectin. There is no cellulase in the human digestive tract. Cellulose is an important dietary fiber. The most widely distributed and abundant polysaccharide in nature.

nature:

1. Solubility

At room temperature, cellulose is insoluble in water and general organic solvents such as alcohol, ether, acetone, benzene, etc. It is also insoluble in dilute alkaline solutions. Therefore, at room temperature, it is relatively stable because of the presence of hydrogen bonds between cellulose molecules. Cellulose is insoluble in water and organic solvents such as ethanol and ether, but is soluble in copper ammonia Cu(NH3)4(OH)2 solution and copper ethylenediamine [NH2CH2CH2NH2]Cu(OH)2 solution.

2. Cellulose hydrolysis

Under certain conditions, cellulose reacts with water. During the reaction, the oxygen bridges break and water molecules are added, and cellulose changes from long-chain molecules to short-chain molecules until all oxygen bridges break and it turns into glucose.

3. Cellulose oxidation

Cellulose reacts chemically with oxidants to produce a series of substances with different structures from the original cellulose. This reaction process is called cellulose oxidation. (Quoted from Guo Lizhu's Archives Protection Technology) The base ring of the cellulose macromolecule is a macromolecular polysaccharide composed of D-glucose with β-1,4 glycosidic bonds. Its chemical composition contains 44.44% carbon, 6.17% hydrogen, and 49.39% oxygen. Due to different sources, the number of glucose residues in a cellulose molecule, i.e., the degree of polymerization (DP), ranges widely. It is the main component of the cell walls of vascular plants, lichens and some algae. Cellulose has also been found in the capsules of Acetobaeter and the tunicates of urochordates. Cotton is a high-purity (98%) cellulose. The name α-cellulose refers to the part of the original cell wall that cannot be extracted by 17.5% NaOH from the standard sample of complete cellulose. β-cellulose and γ-cellulose are celluloses corresponding to hemicellulose. Although α-cellulose is usually mostly crystalline cellulose, β-cellulose and γ-cellulose chemically contain various polysaccharides in addition to cellulose. The cellulose of the cell wall forms microfibrils. The width is 10-30 nanometers, and some are several microns long. Using X-ray diffraction and negative staining methods, according to electron microscopy observations, it was found that the crystalline parts of the parallel arrangement of chain molecules formed basic microfibers with a width of 3-4 nanometers. It is speculated that these basic microfibrils are combined to form microfibrils. Cellulose is soluble in Schwitzer's reagent or concentrated sulfuric acid. Although it is not easily hydrolyzed by acid, dilute acid or cellulase can convert cellulose into D-glucose, cellobiose and oligosaccharides. In acetic acid bacteria, there is an enzyme that transfers glycosides from UDP glucose primers (cellulose synthase (UDP forming EC2.4.1.12) to synthesize cellulose. Standard samples of granular enzymes with the same activity have been obtained in higher plants. This enzyme usually uses GDP glucose (cellulose synthase (GDP forming) EC2.4.1.29), and when transferred from UDP glucose, a mixture of β-1,3 bonds occurs. The site of microfibril formation and the mechanism that controls cellulose arrangement are not very clear. On the other hand, as far as the decomposition of cellulose is concerned, it is estimated that when the primary cell wall stretches and grows, part of the microfibrils are decomposed by the action of cellulase and become soluble.

Water can cause limited swelling of cellulose, and aqueous solutions of certain acids, alkalis and salts can penetrate into the crystalline area of ​​the fiber, causing unlimited swelling and dissolving the cellulose. Cellulose does not change significantly when heated to about 150°C, but will gradually carbonize due to dehydration above this temperature. Cellulose is hydrolyzed with concentrated inorganic acids to produce glucose, etc., reacts with concentrated caustic alkaline solutions to produce alkaline cellulose, and reacts with strong oxidants to produce oxidized cellulose.

4. Flexibility

Cellulose has poor flexibility and is rigid because:

(1) Cellulose molecules are polar, and the interaction between molecular chains is very strong;

(2) The six-membered pyran ring structure in cellulose makes internal rotation difficult;

(3) Hydrogen bonds can be formed both within and between cellulose molecules, especially intramolecular hydrogen bonds, which prevent the glycosidic bonds from rotating, thus greatly increasing its rigidity.