Baking powder is a compound additive mainly used in the production of flour products and puffed foods. Baking powder contains a variety of substances, the main components of which are sodium bicarbonate and tartaric acid. Usually a compound of carbonate and solid acid. When carbonates come into contact with water and acids, they break down into a variety of substances. During this process, a high is released, but no flavor is produced. Therefore, the taste of the product is inconvenient.     Fermentation   There are generally three fermentation methods for making fermented dough: old yeast, fresh yeast, and baking powder. Fresh yeast and baking powder are commonly used in households. Pay careful attention to the aluminum content in baking powder. Aluminum content in food exceeding national standards can cause harm to the human body.   Yeast and baking powder both have the function of fermentation, but they are essentially different.   Yeast is a pure biological leavening agent, an active microorganism, which will not cause any harm to the human body; while chemical baking powder is a chemical leavening agent, generally referring to baking soda (sodium bicarbonate), stink powder (ammonium bicarbonate), alum ( Potassium aluminum sulfate or potassium aluminum sulfate, SAS), baking powder (baking powder) and other substances.   Classification   chemical leavening agent   baking powder   1. Baking soda ( sodium bicarbonate ,): Under the action of acidic substances contained in food , baking soda can be decomposed into sodium ions , water and carbon dioxide gas, the latter of which can fluff food. However, the reaction of baking soda to release gas requires the presence of acidic substances and is completed in a very short time. The initiation of the reaction is difficult to control. If the dosage is too large, it will produce a bitter or astringent taste . For these reasons, baking soda is rarely used as a leavening agent alone, and is generally used as one of the components of a compound leavening agent.   2. Stinky powder ( ammonium bicarbonate ): Stinky powder is generally used when a large amount of gas needs to be generated quickly. Stinky powder will decompose into water, ammonia and carbon dioxide gas when heated or under acidic conditions . Due to the rapid release, very little ammonia gas remains in the finished product, and there will be no ammonia smell in the finished product. Since stink powder easily decomposes and releases ammonia gas (this is where the name of stink powder comes from) and loses its effect, it is difficult to store and is generally rarely used in households. Stinky powder is used when baking peach cakes or certain biscuits.   3. Alum (potassium aluminum sulfate or potassium aluminum sulfate, SAS): Commonly used alum is actually an acidic mixture, which releases gas when it interacts with food’s inherent or added ingredients such as baking soda, which has a fluffy effect. It is generally also an acid component used as a compound fluffing agent. The characteristic is that it can react quickly at high temperatures . A common example is for frying fried dough sticks   baking powde   1. Baking powder: It is a compound leavening agent, and there are many different types. Generally, solid alkali and acid powders are mixed . They do not contact or react under dry conditions. Once they come into contact with water, they will dissolve and contact, and the reaction will release gas. Solid alkali powder is commonly used in baking soda, and solid acid powder includes tartar ( tartar) and phosphate (phosphate, such as calcium phosphate and sodium pyrophosphate ). Their reaction speeds are very fast; in addition, alum (SAS) is used. ) as a solid acid, the reaction rate is much slower, but very fast at high temperatures. Alum is commonly found in Double-acting (DA) baking powders. Double effect means that after mixing water and flour, baking soda first reacts with a fast solid acid (such as cream of tartar) to release the first batch of gas. At this time, alum and baking soda basically do not react, but when heated, alum When heated with baking soda, a second batch of gas is released, which is called double-acting. Commonly seen on the market is double active baking powder. Some self-raising flours also have baking powder already mixed into them and need to be baked quickly after adding water. Because baking powder is easy to store and easy to control, it has become the most commonly used leavening agent and is used in most Western-style pastries.   2. Dangers of chemical leavening agents :   Since the reaction products of baking soda and stink powder ( carbon dioxide , ammonia) are also products of human metabolism, as long as they are not used excessively, they will not cause obvious health problems , but they will destroy certain nutrients in food such as vitamins. And both alum and baking powder contain aluminum. Many international reports have pointed out that aluminum is closely related to Alzheimer’s disease . It also reduces memory, suppresses immune function , and hinders nerve conduction . Moreover, aluminum is excreted very slowly from the human body. The amount of alum and baking powder in food should be strictly controlled. Use and try to eat less aluminum-containing foods.   biological leavening agent   Yeast is a unicellular facultative anaerobic eukaryotic microorganism. After being added to the dough, it can produce carbon dioxide gas through its own metabolism to achieve the purpose of fluffiness. This process is often called fermentation. In the past, old noodles were often fermented, mainly relying on wild yeast and some miscellaneous bacteria. Dough usually contains organic acids, which give it a sour taste. Baking soda needs to be added to neutralize the sour taste. Bacterial metabolites and added baking soda may introduce harmful ingredients or destroy nutrients.   The active yeast commonly used in modern times has high purity and rarely produces acidic substances. At the same time, yeast itself is composed of protein and carbohydrates, and is rich in B vitamins and other trace elements such as calcium and iron, and is rich in nutrients. value. Yeast acts as a leavening agent for pasta and requires sufficient time and temperature to produce carbon dioxide.   Obviously, yeast is a beneficial biological leavening agent that has no negative impact on the human body and can provide nutrients and vitamins that humans need but lack. is the most ideal fermentation method. It is essentially different from chemical baking powder. Simply put, yeast is not chemical baking powder!

Kaolin, theoretical chemical formula: Al 2 [(OH) 4 /Si 2 O 5 ] , It is a non-metallic mineral , a kind of clay and clay rock mainly composed of kaolinite clay minerals . Because it is white and delicate, it is also called dolomitic soil . It is named after Gaoling Village , Jingdezhen , Jiangxi Province. Its pure kaolin is white, delicate, soft and earthy, and has good physical and chemical properties such as plasticity and fire resistance. Its mineral composition is mainly composed of kaolinite , halloysite , hydromica , illite, montmorillonite , quartz, feldspar and other minerals. Kaolin is widely used, mainly used in papermaking, ceramics and refractory materials . Secondly, it is used in coatings, rubber fillers, enamel glazes and white cement raw materials. In small quantities, it is used in plastics, paints, pigments, grinding wheels, pencils, daily cosmetics, soaps, etc. Pesticides, medicines, textiles, petroleum, chemicals, building materials, national defense and other industrial sectors. Composition Kaolin minerals are composed of kaolinite cluster minerals such as kaolinite, dikaiite, perlite, and halloysite. The main mineral component is kaolinite. The crystal chemical formula of kaolinite is 2SiO 2 ·Al 2 O 3 ·2H 2 O, and its theoretical chemical composition is 46.54% SiO 2 , 39.5% Al 2 O 3 , and 13.96% H 2 O. Kaolin minerals are 1:1 type layered silicates. The crystals are mainly composed of silicon-oxygen tetrahedrons and aluminum-hydrogen-oxygen octahedrons. The silicon-oxygen tetrahedrons are connected along two-dimensional directions by sharing vertex angles to form a hexagonal arrangement. In the grid layer, the unshared peak oxygen of each silicon-oxygen tetrahedron faces one side; a 1:1 type unit layer is composed of the silicon-oxygen tetrahedron layer and the oxygen-absorbing octahedron layer sharing the peak oxygen of the silicon-oxygen tetrahedron layer Physical and chemical properties Properties: Mostly matte, white and delicate when pure, but may be gray, yellow, brown and other colors when containing impurities. The appearance can be loose soil lumps or dense rock lumps depending on the origin. Density: 2.54-2.60 g/cm3. Melting point: about 1785℃. It is plastic, and wet soil can be molded into various shapes without breaking, and can remain unchanged for a long time Origin of mineral deposits Kaolin is a common and very important clay mineral in nature. It is formed by the weathering of feldspar or other silicate minerals in igneous and metamorphic rocks in acidic media lacking alkali metals and alkaline earth metals . Soil classification The minerals contained in kaolin in nature are mainly divided into clay minerals and non-clay minerals. Among them, clay minerals mainly include kaolinite minerals and a small amount of montmorillonite, mica and chlorite; non-clay minerals mainly include feldspar, quartz and hydrated minerals, as well as some iron minerals such as hematite and rhosite. Iron ore , limonite , etc., titanium minerals such as rutile, etc. and organic matter such as plant fiber , etc. It is mainly clay minerals that determine the properties of kaolin . Cause classification Based on the origin of kaolin deposits and based on the differences in mineralization geology, geographical conditions, deposit scale, ore body morphology and occurrence characteristics, ore material components reflected in different mineralization processes, the “Kaolin Mine Geological Exploration Code” will China’s kaolin deposits are divided into three types and six subtypes. 1. Weathering type: It is further divided into weathering residual subtype and weathering leaching subtype; 2. Hydrothermal alteration type: It is further divided into hydrothermal alteration subtype and modern hot spring alteration subtype; 3. Sedimentary type: It is further divided into sedimentary and sedimentary-weathering subtypes and kaolinite claystone subtype in coal-bearing strata. Industrial type It is divided into three types according to its texture, plasticity and sandy quality fraction: 1. Hard kaolin: hard and non-plastic, it can become plastic after being crushed and finely ground. 2. Soft kaolin: soft, strong plasticity, sand mass fraction <50%; 3. Sandy kaolin: soft, weak plasticity , sand mass fraction >50%. Process characteristics whiteness brightness Whiteness is one of the main parameters of kaolin’s technological performance. Kaolin with high purity is white. The whiteness of kaolin clay is divided into natural whiteness and calcined whiteness. For ceramic raw materials , the whiteness after calcining is more important. The higher the calcined whiteness, the better the quality. Ceramic technology stipulates that drying at 105°C is the grading standard for natural whiteness, and calcining at 1300°C is the grading standard for calcined whiteness. Whiteness can be measured with a whiteness meter. A whiteness meter is a device that measures the reflectivity of light with a wavelength of 3800-7000Å (i.e. angstrom, 1 angstrom = 0.1 nanometer). In the whiteness meter, the reflectance of the sample to be tested is compared with that of the standard sample (such as BaSO4, MgO, etc.), which is the whiteness value (for example, a whiteness of 90 means that it is equivalent to 90% of the reflectance of the standard sample). Brightness is a process property similar to whiteness, equivalent to the whiteness under irradiation of 4570Å (angstrom) wavelength light. The color of kaolin is mainly related to the metal oxides or organic matter it contains . Generally, those containing Fe2O3 are rose red and brown; those containing Fe2+ are light blue and light green; those containing MnO2 are light brown; those containing organic matter are light yellow, gray, green, black and other colors. The presence of these impurities reduces the natural whiteness of kaolin. The iron and titanium minerals also affect the calcined whiteness, causing stains or melting scars on the porcelain. Particle size distribution Particle size distribution refers to the proportion (expressed in percentage) of the particles in natural kaolin within a given continuous range of different particle sizes (expressed in meshes with millimeter or micron mesh openings). The particle size distribution characteristics of kaolin are of great significance to the selection of ores and process applications. Its particle size has a great impact on its plasticity, mud viscosity, ion exchange capacity, molding performance, drying performance, and firing performance. Kaolin ore requires technical processing. Whether it is easy to process to the fineness required by the process has become one of the criteria for evaluating the quality of the ore. Various industrial sectors have specific particle size and fineness requirements for kaolin clay for different uses. For example, the United States requires 90-95% of kaolin used as coatings to have a content less than 2 μm, and 78-80% of papermaking fillers less than 2 μm. plasticity The mud formed by the combination of kaolin and water can deform under the action of external force. The property of retaining this deformation after the external force is removed is called plasticity. Plasticity is the basis of the kaolin molding process in ceramic bodies and is also the main process technology indicator. Plasticity index and plasticity index are usually used to express the degree of plasticity. The plasticity index refers to the liquid limit moisture content of kaolin clay material minus the plastic limit moisture content, expressed as a percentage, that is, W plasticity index = 100 (W liquid limit – W plastic limit). The plasticity index represents the molding performance of kaolin clay material. It can be obtained by directly measuring the load and deformation of the mud ball when it is crushed under pressure using a plasticity meter. It is expressed in kg·cm. The higher the plasticity index, the better the molding performance. The plasticity of kaolin can be divided into four levels. Plasticity strength plasticity index plasticity index Strong plasticity>153.6 Medium plasticity 7-152.5-3.6 Weak plasticity 1-7<2.5 Non-plasticity<1 associativity Combinability refers to the ability of kaolin clay to combine with non-plastic raw materials to form a plastic mud mass with a certain dry strength. The binding ability is measured by adding standard quartz sand to kaolin clay (its mass composition is 0.25-0.15 grain size accounts for 70%, and 0.15-0.09mm grain size accounts for 30%). Its level is judged by its highest sand content when it can still maintain a plastic mud mass and its flexural strength after drying. The more sand is added, the stronger the bonding ability of the kaolin. Generally, kaolin clay with strong plasticity also has strong binding ability. viscosity Viscosity refers to a characteristic of a fluid that hinders its relative flow due to internal friction. Its size is represented by viscosity (the internal friction acting on 1 unit area), and the unit is Pa·s. The viscosity is generally measured using a rotational viscometer, measured by the rotational speed in kaolin mud containing 70% solid content . In the production process, viscosity is of great significance. It is not only an important parameter in the ceramic industry, but also has a great impact on the paper industry. According to data, when kaolin is used as coating abroad, the viscosity is required to be about 0.5 Pa·s when coating at low speed, and less than 1.5Pa·s when coating at high speed. Thixotropy refers to the characteristic that mud that has thickened into a gel-like state and no longer flows becomes fluid after being stressed, and then gradually thickens back to its original state after being stationary. Its size is represented by the thickening coefficient and measured using an outflow viscometer and a capillary viscometer. The viscosity and thixotropy are related to the mineral composition , particle size and cation type in the mud . Generally, those with a large montmorillonite content, fine particles, and exchangeable cations mainly containing sodium will have high viscosity and thickening coefficient. Therefore, methods such as adding strong plasticity clay and increasing fineness are commonly used to increase its viscosity and thixotropy, and methods such as increasing dilute electrolyte and moisture are used to reduce it. Drying performance Drying performance refers to the performance of kaolin mud during the drying process. Including drying shrinkage, drying strength and drying sensitivity. Drying shrinkage refers to the shrinkage of kaolin clay material after it loses water and dries. Kaolin mud generally dehydrates and dries at a temperature of 40-60°C and no more than 110°C. Due to the discharge of water, the distance between particles is shortened, and the length and volume of the sample will shrink. Drying shrinkage is divided into line shrinkage and volume shrinkage, expressed as the percentage change in length and volume of kaolin clay material after it is dried to constant weight. The drying line shrinkage of kaolin is generally 3-10%. The finer the particle size, the larger the specific surface area, the better the plasticity, and the greater the drying shrinkage. The same type of kaolin has different shrinkage due to different blends of water. Those with more water will shrink more. In the ceramic process, if the drying shrinkage is too large, the green body is prone to deformation or cracking. Dry strength refers to the flexural strength of mud after it is dried to constant weight. Drying sensitivity refers to the degree of difficulty with which the green body may tend to deform and crack when drying. High sensitivity, easy to deform and crack during drying process. Generally, kaolin with high drying sensitivity (drying sensitivity coefficient K>2) is easy to form defects; kaolin with low drying sensitivity (drying sensitivity coefficient K<1) is safer during drying. Sinterability Sinterability refers to the property that when the formed solid powdered kaolin body is heated to close to its melting point (generally over 1000°C), the substance spontaneously fills the gaps between the particles and becomes densified. The state in which the porosity drops to the minimum value and the density reaches the maximum value is called the sintering state, and the corresponding temperature is called the sintering temperature . As the heating continues, the liquid phase in the sample continues to increase and the sample begins to deform. The temperature at this time is called the transformation temperature. The interval between the sintering temperature and the transformation temperature is called the sintering range. Sintering temperature and sintering range are important parameters in determining the blank formula and selecting the type of kiln in the ceramic industry . The sample should have a low sintering temperature and a wide sintering range (100-150°C). In terms of technology, the sintering temperature and sintering range can be controlled by blending fluxing raw materials and blending different types of kaolin in proportion. Firing shrinkage Firing shrinkage refers to a series of physical and chemical changes that occur in the dried kaolin blank during the firing process (dehydration, decomposition, formation of mullite , melting of fusible impurities to form a glass phase that fills the gaps between particles, etc.) , and the properties that cause product shrinkage are also divided into two types: linear shrinkage and body shrinkage. Like drying shrinkage, excessive firing shrinkage can easily lead to cracking of the green body. In addition, if a large amount of quartz is mixed in the blank during roasting , it will undergo crystal transformation fire resistance Fire resistance refers to the ability of kaolin to withstand high temperatures without melting. The temperature at which it softens and begins to melt under high-temperature operations is called refractoriness. It can be measured directly using a standard thermometer cone or high-temperature microscope, or it can be measured using M. A. Calculated using Bezbelodov’s empirical formula . Refractoriness t (℃)=[360+Al2O3-R2O]/0.228 In the formula: Al2O3 is the mass percentage of Al2O3 when the sum of the analysis results of SiO2 and Al2O3 is 100; R2O is the mass percentage of other oxides when the sum of the analysis results of SiO2 and Al2O3 is 100. The error of calculating refractory degree through this formula is within 50℃. The refractory degree is related to the chemical composition of kaolin. The refractory degree of pure kaolin is generally around 1700°C. When the content of hydromica and feldspar is high, and the content of potassium, sodium and iron is high, the refractory degree is reduced. The minimum refractory degree of kaolin is not less than 1500℃. The industrial sector stipulates that the R2O content of refractory materials is less than 1.5-2%, and the Fe […]

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% Grain […]