Cellulose is a macropolysaccharide 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. The cellulose content of cotton is close to 100%, making it the purest natural source of cellulose. In general, cellulose accounts for 40-50% of wood, 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 extent of its combination has a great impact on the texture of plant-derived foods. The changes in texture of plants during maturity and post-ripening are caused by changes in pectin substances. Cellulase does not exist in the human digestive tract, and cellulose is an important dietary fiber. It is the most widely distributed and abundant polysaccharide in nature.   nature   solubility   At room temperature, cellulose is neither soluble in water nor general organic solvents, such as alcohol , ether , acetone , benzene , etc. It is also insoluble in dilute alkali solutions and can be dissolved in cuprammonium Cu(NH 3 ) 4 (OH ) 2 solution and copper ethylenediamine [NH 2 CH 2 CH 2 NH 2 ]Cu(OH) 2 solution, etc. Therefore, it is relatively stable at room temperature because of the hydrogen bonds between cellulose molecules .   Cellulose hydrolysis   Under certain conditions, cellulose reacts with water. During the reaction, the oxygen bridge is broken, and water molecules are added at the same time, and the cellulose changes from long chain molecules to short chain molecules until all the oxygen bridges are broken and becomes glucose.   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. 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 cellulose molecules, that is, the degree of polymerization (DP), is in a wide range. It is the main component of the cell walls of vascular plants , lichen plants , and some algae. Cellulose is also found in the capsules of Acetobaeter and the tunicates of urochordates. Cotton is a highly pure (98%) cellulose. The name α-cellulose refers to the part of the original cell wall of the complete cellulose standard sample that cannot be extracted with 17.5% NaOH. β-cellulose (β-cellulose) and γ-cellulose (γ-cellulose) are cellulose 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 the length can reach several micrometers. Apply X-ray diffraction and negative staining methods(Negative staining method), according to electron microscope observation, the crystalline parts of chain-like molecules arranged in parallel form basic microfibers with a width of 3-4 nanometers. It is speculated that these basic microfibers are aggregated to form microfibers. Cellulose can be dissolved in Schwitzer’s reagent or concentrated sulfuric acid. Although it is not easily hydrolyzed by acid, dilute acid or cellulase can produce D-glucose, cellobiose and oligosaccharides from cellulose . Acetic acid bacteria have an enzyme that transfers glycosides from UDP glucose primer to synthesize cellulose.   Standard samples of granular enzymes with the same activity have been obtained in higher plants. This enzyme usually utilizes GDP glucose, and in the case of transfer from UDP glucose, mixing of β-1,3 bonds occurs. Where microfibrils form and the mechanisms that control cellulose alignment are less clear. On the other hand, regarding the decomposition of cellulose, it is estimated that when the primary cell wall stretches and grows, part of the microfibers is decomposed by the action of cellulase and becomes soluble.   Water can cause limited swelling of cellulose, and certain aqueous solutions of acids, alkalis, and salts can penetrate into the crystalline area of ​​the fiber, causing unlimited swelling and dissolving the cellulose. Cellulose does not undergo significant changes when heated to about 150°C. Above this temperature it will gradually coke due to dehydration. Cellulose reacts with concentrated inorganic acids to hydrolyze to produce glucose, reacts with concentrated caustic alkali solutions to produce alkali cellulose, and reacts with strong oxidants to produce oxidized cellulose.   Flexibility   Cellulose has poor flexibility and is rigid because:   (1) Cellulose molecules are polar and the interactions between molecular chains are 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. In particular, intramolecular hydrogen bonds prevent the glycosidic bonds from rotating, thereby greatly increasing their rigidity.   Preparation method   Production method 1: Cellulose is the most abundant natural polymer compound in the world. The production raw materials come from wood, cotton, cotton linters, wheat straw, rice straw, reed, hemp, mulberry bark, mulberry bark and sugarcane bagasse. Due to insufficient forest resources in our country, 70% of cellulose raw materials come from non-timber resources. The average cellulose content of my country’s softwood and broadleaf wood is about 43-45%; the average cellulose content of grass stems is about 40%. The industrial production method of cellulose is to cook plant raw materials with sulfite solution or alkali solution, mainly to remove lignin, which are called sulfite method and alkali method respectively. The resulting materials are called sulfite pulp and alkali pulp. The residual lignin is then further removed through bleaching, and the resulting bleached pulp can be used for papermaking. After further removing hemicellulose, it can be used as a raw material for cellulose derivatives.   Production method two: Pound fibrous plant raw materials and inorganic acid into a slurry to make α-cellulose, and then process it to partially depolymerize the cellulose, and then remove the non-crystalline part and purify it.   Production method three: decompose the selected industrial wood pulp board, and then send it to a reaction kettle with 1% to 10% hydrochloric acid (the dosage is 5% to 10%) for hydrolysis at a temperature of 90 to 100°C. The reaction time is 0.5 to 2 hours. After the reaction is completed, it is cooled and sent to a neutralization tank. It is adjusted to neutrality with liquid caustic soda. After filtration, the filter cake is dried at 80 to 100°C and finally crushed to obtain the product.   Production method four: cellulose made from wood pulp or cotton pulp. It is refined after bleaching treatment and mechanical dispersion.   effect   Cellulose is the oldest and most abundant natural polymer on earth. It is inexhaustible and the most precious natural renewable resource for mankind. Cellulose chemistry and industry began more than 160 years ago and was the main research object during the birth and development period of polymer chemistry. The research results of cellulose and its derivatives contributed to the creation, development and enrichment of the disciplines of polymer physics and chemistry. Made significant contributions.   Physiological effects   There is no β-glycosidase in the human body and cellulose cannot be decomposed and utilized. However, cellulose can absorb a large amount of water, increase the amount of feces, promote intestinal peristalsis, accelerate the excretion of feces, and shorten the residence time of carcinogens in the intestines. Reduces adverse irritation to the intestines, thereby preventing intestinal cancer.   Dietary fiber   The fiber in human diet is mainly contained in vegetables and roughly processed cereals. Although it cannot be digested and absorbed, it can promote intestinal peristalsis and facilitate fecal discharge. Herbivores rely on symbiotic microorganisms in their digestive tracts to break down cellulose so it can be absorbed and utilized. Food fiber includes crude fiber, semi-crude fiber and lignin. Food fiber is a substance that cannot be digested and absorbed. In the past, it was considered as “waste”. In 2013, it was considered that it plays an important role in protecting human health and prolonging life. Therefore, it is called the seventh nutrient.   Dietary fiber generally uses various types of high-purity dietary fiber extracted from natural foods (konjac, oats, buckwheat, apples, cactus, carrots, etc.). The main functions of dietary fiber are:   (1) Treatment of diabetes Dietary fiber can improve the sensitivity of insulin receptors and improve the utilization rate of insulin ; dietary fiber can wrap the sugar in food so that it is gradually absorbed, balancing postprandial blood sugar, thus regulating the blood sugar level of diabetic patients and treating diabetes. role.   (2) Prevention and treatment of coronary heart disease Elevated serum cholesterol levels can lead to coronary heart disease. The excretion of cholesterol and bile acid is closely related to dietary fiber. Dietary fiber can combine with cholic acid, causing cholic acid to be quickly excreted from the body. At the same time, the combination of dietary fiber and cholic acid will promote the conversion of cholesterol into cholic acid, thereby reducing cholesterol levels.   (3) Antihypertensive effect Dietary fiber can absorb ions and exchange with sodium ions and potassium ions in the intestines, thereby reducing the sodium-potassium ratio in the blood and thus lowering blood pressure.   (4) Anti-cancer effect Since the 1970s, there have been an increasing number of research reports on the role of dietary fiber in anti-cancer, especially the relationship between dietary fiber and digestive tract cancer. Early surveys in India showed that people living in northern India consumed much more dietary fiber than those in the south, and the incidence of colon cancer was also much lower than in the south. Based on this survey result, scientists conducted more in-depth research and found that dietary fiber prevents and treats colon cancer for the following reasons: some saprophytic bacteria in the colon can produce carcinogens, and some beneficial microorganisms in the intestine can use dietary fiber to produce short-chain fatty acids . This type of short-chain fatty acid can inhibit the growth of saprophytic bacteria; cholic acid and ichonecholic acid in bile can be metabolized by bacteria into carcinogens and mutagens of cells. Dietary fiber can bind cholic acid and other substances and excrete them out of the body, preventing The production of these carcinogens; dietary fiber can promote intestinal peristalsis, increase stool volume, shorten emptying time, thereby reducing the chance of contact between carcinogens in food and the colon; beneficial bacteria in the intestines can use dietary fiber to produce butyric acid, butyric acid It can inhibit the growth and proliferation of tumor cells, induce the transformation of tumor cells into normal cells, and control the expression of oncogenes.   (5) Weight loss and treatment of obesity Dietary fiber replaces part of the nutrients in food, reducing the total food intake. Dietary fiber promotes the secretion of saliva and digestive juices, filling the stomach. At the same time, it absorbs water and expands, which can produce a feeling of satiety and inhibit the desire to eat. Dietary fiber combines with some fatty acids. This combination prevents the fatty acids from being absorbed when they pass through the digestive tract, thus reducing the absorption rate of fat.   (6) Treat constipation Dietary fiber has strong water-holding properties, and its water absorption rate is as high as 10 times. After it absorbs water, it increases the volume of intestinal contents, making stool loose and soft, making it smoother and less laborious when passing through the intestines. At the same time, dietary fiber, as a foreign body in the intestine, can stimulate the contraction and peristalsis of the intestine, speed up stool excretion, and cure constipation.   Research results   An international team, including researchers from the University of Göttingen in Germany, were surprised to find that despite the simulated Martian atmosphere disrupting the microbial ecology of the kombucha cultures, they were studying the possibility of kombucha surviving in a Martian-like environment. A cellulose-producing bacterium of the genus Colomata survived. The findings were recently published in the journal Frontiers in Microbiology. The findings suggest that cellulose produced by bacteria may be responsible for their survival in alien conditions. It also provides the first evidence that bacterial cellulose may be a biomarker of alien life, and that cellulose-based membranes may be good materials for protecting life in alien colonies.   In 2014, researchers with the Biology and Mars Experiment (BIOMEX) project, supported by the European Space Agency (ESA), sent kombucha cultures to the International Space Station (ISS) to better understand cellulose as a biomarker the robustness of animals, the genome structure of kombucha, and its alien survival behavior. The samples were reactivated on Earth and cultured a year and a half later for another two and a half years outside the ISS under simulated Martian conditions.   ingest   Vegetables are rich in fiber. Foods that do not contain fiber include: chicken, duck, fish, meat, eggs, etc.; foods that contain a lot of fiber include: whole grains, bran, vegetables, beans, etc., among which cotton has the highest content, reaching 98%. Therefore, it is recommended that diabetic patients eat more fiber-rich foods such as beans and fresh vegetables. At present, domestic plant fiber foods are mostly made from rice bran, bran, wheat grains, beet shavings, pumpkins, corn husks and seaweed plants, etc., which have a certain effect on lowering blood sugar and blood lipids.   Content and determination   Although fiber cannot be absorbed by the human body, it has a good effect on cleaning the intestines and is a healthy food suitable for patients with IBS (irritable bowel syndrome). The fiber content of common foods is as follows:   Wheat bran: 31% Grains: 4-10%, arranged from most to least: wheat grains, barley, corn, buckwheat noodles, barley noodles, sorghum rice, and black rice. Cereal: 8-9%; Oatmeal: 5-6% The cellulose content of potatoes, sweet potatoes and other tubers is about 3%. Beans: 6-15%, from most to least, they are soybeans, green beans, broad beans, kidney beans, peas, black beans, red beans, and mung beans.   Whether cereals, potatoes or beans, generally speaking, the more finely processed they are, the less fiber they contain.   Vegetables: Bamboo shoots have the highest content. The fiber content of dried bamboo shoots reaches 30-40%, and the fiber content of peppers exceeds 40%. Others containing more fiber include: bracken, cauliflower, spinach, pumpkin, cabbage, and rapeseed.   Fungi (dry): The cellulose content is the highest. Among them, the cellulose content of pine mushrooms is close to 50%. The cellulose content of more than 30% is arranged from most to least: shiitake mushrooms, tremella, and fungus. In addition, the fiber content of seaweed is also high, reaching 20%.   Nuts: 3-14%. More than 10% include: black sesame seeds, pine nuts, and almonds; less than 10% include white sesame seeds, walnuts, hazelnuts, walnuts, sunflower seeds, watermelon seeds, and peanut kernels.   Fruits: Dried red fruits contain the most fiber, with a fiber content of nearly 50%, followed by dried mulberries, cherries, wild jujubes, black dates, jujubes, small jujubes, pomegranates, apples, and pears.   All kinds of meat, eggs, dairy products, various oils, seafood, alcoholic beverages, and soft drinks do not contain cellulose; the fiber content of various infant foods is extremely low.   Cellulose is not fiber, they are two different concepts. Cellulose is measured using a cellulose analyzer. Crude fiber is generally measured, and dietary fiber is also measured in foods   Medicinal introduction   Natural dietary fiber tablets   (1) Edible purpose : Moisturizes the intestines and relieves constipation, provides a feeling of satiety and breaks down fat.   (2) Product features : Scientific formula derived from natural ingredients helps normal physiological activities and helps you feel full. Fiber can remove disease-causing toxins from the body through the digestive system. Shorten the time food stays in the intestines and make bowel movements smooth.Made of a unique combination of fibers that break down ingested fat.   (3) Main ingredients : Calcium hydrogen phosphate, cellulose, apple fiber, acacia flower, lecithin, calcium carbonate, citrus fiber, silicon dioxide, oat fiber, magnesium stearate, dextrin, maltodextrin, sodium carboxymethylcellulose, citric acid sodium.   (4) Recommended usage : Take one to two tablets each time for laxative, three times a day, 20 minutes before meals or with boiled water after meals.   Fiber and health   Not all carbohydrates can be digested and converted into glucose. Carbohydrates that are difficult to digest are called fiber. It is an integral part of a healthy diet and is found in higher amounts in fruits, vegetables, lentils, beans and whole grains. Eating foods high in fiber can reduce the likelihood of bowel cancer, diabetes and diverticular disease. It is also less prone to constipation.   People often think of fiber as “forage,” but that’s not the case. Fiber absorbs water. Therefore, it makes food particles expand and loosen, making them easier to pass through the digestive tract. Since the time that food residues stay in the body is shortened, the risk of infection is reduced; moreover, when some foods, especially meat, spoil, they will produce carcinogens and cause cell mutations. The shortening of the time that food residues stay in the body can also reduce the risk of infection. Reduce the likelihood of this happening. Regular meat eaters’ diets are low in fiber, which increases the time food remains in the intestines to 24-72 hours, during which time some food may spoil. So if you like to eat meat, then you have to make sure that you also include plenty of fiber in your diet.   There are many types of fiber, some of which are proteins rather than carbohydrates. Some types of fiber, like the kind found in oats, are called “soluble fiber” and bind to sugar molecules to slow the absorption of carbohydrates. This way they help keep blood sugar levels stable. Some fibers are much more absorbent than others. Wheat fiber can swell to 10 times its original volume in water, while glucomannan fiber in Japanese konjac can swell to 100 times its original volume in water. Because fiber bulks food and slows the release of energy from sugars, highly absorbent fiber can help control appetite and help maintain proper weight.   The ideal fiber intake is no less than 35 grams per day. With proper food selection, this standard can easily be achieved without the need for additional supplementation. It’s still best to get your fiber from a number of different food sources, including oats, lentils, broad beans, seeds, fruits, and raw or lightly cooked vegetables. Most of the fiber in vegetables is destroyed during cooking, so vegetables are best eaten raw.