What is the composition of rice bran?

Rice bran is a by-product of rice processing, which has high nutritional value and development prospect. This paper focuses on the research status and development trend of functional components of rice bran, providing reference for comprehensive utilization of rice bran. Keywords: rice bran; Functional components; Research status: development trend; The comprehensive utilization of rice bran is the husk of Gramineae rice, which is a mixture of crushed cortex, rice embryo and a small amount of broken rice, accounting for about 5% ~ 6% of rice. It is not only rich in resources, but also comprehensive in nutrition. Rice bran is rich in unsaturated fatty acids, tocopherols, tocotrienols, lipopolysaccharide, dietary fiber, squalene, γ-oryzanol and other physiologically active substances. These substances play a significant role in preventing cardiovascular and cerebrovascular diseases, anti-cancer, enhancing immunity, reducing blood lipid, preventing constipation and obesity. They are important raw materials for health food, medicine and chemical manufacturing, and have been widely valued by countries all over the world. At the same time, rice bran contains lipase with strong activity, which can quickly decompose the oil contained in rice bran, make the acid value rise rapidly, and may be further oxidized by lipoxygenase (commonly known as "Harbin"), resulting in unacceptable musty smell in a short time. At room temperature, the acid value of fresh rice bran can be increased from 4mg KOH/g to more than 65,438+00 mg KOH/g in a few hours, and the free fatty acid content of rice bran increases at a rate of about 65,438+0%/h at 25℃. The life activities of mixed pests and microorganisms in rice bran will also accelerate the rancidity and deterioration of rice bran. Therefore, it is necessary to inactivate this enzyme and stabilize rice bran before further development. The deep development and utilization of rice bran resources must be intensively managed, otherwise it is difficult to achieve economies of scale, and it does not have the conditions of technology, technology and equipment. Although the total output of rice bran in China is very large, it is difficult to concentrate production because of the scattered rice processing enterprises, small production scale and poor stability of fresh rice bran, which is not convenient for storage and transportation. At present, the effective utilization rate of rice bran is less than 20%, and most of it is used as feed or even waste, which is a serious waste of resources. 1 nutritional components and physiological functions of rice bran rice bran is the product of brown rice milling. When brown rice is ground white, the mixture of rice husk (endosperm), rice germ and a small amount of broken endosperm (broken rice and chaff) is usually called rice bran. Although the weight of rice bran is less than 10% of that of brown rice, the important nutrients of brown rice are concentrated in rice bran. Rice bran contains protein 12% ~ 16%, fat 12% ~ 23%, crude fiber 8% ~ 10% and ash 7% ~ 12%. In addition, it is rich in vitamins and minerals, and at least 78% VB is concentrated in brown rice. Rice bran protein contains all essential amino acids, is hypoallergenic, and is suitable for infant food. The fatty acid composition of rice bran oil is about 40% oleic acid and 34% linoleic acid. Rice bran has a high carbohydrate content, but its main component is dietary fiber. In addition, the physiological active substances such as γ-oryzanol, tocopherol, tocotrienols and inositol contained in rice bran are important reasons for its health care function. It is reported that rice bran can reduce serum total cholesterol and low-density lipoprotein cholesterol content, increase high-density lipoprotein cholesterol content, and has many health care functions such as lowering blood lipid, regulating blood sugar, preventing cancer and fatty liver. At present, in the American market, there are many kinds of nutritional and health foods made from rice bran, such as "Perfect Plus", "RiSoTriene" and "RIBUS rice bran beverage", which have good market prospects. The physiological function of rice bran oil and the research status of its deep-processed products. The oil content in rice bran is 14% ~ 24%, which belongs to functional oil and is a high-quality vegetable oil. The fat in rice bran is mainly composed of palmitic acid (about 17%), oleic acid (about 40%) and linoleic acid (about 34%). In addition, it also contains linolenic acid (about 65438 0%), and their total content accounts for about 92% of the total fatty acids. 2. 1 Physiological function of rice bran oil The content of unsaturated fatty acids in rice bran oil is over 80%, and the content of essential fatty acids is 35.7%, which can supplement the deficiency of essential fatty acids in human body. Rice bran oil, as the main raw material of high-grade blended oil, health oil and other high-grade oils, has a good curative effect on human cardiovascular diseases. At the same time, rice bran oil is rich in linoleic acid, and normal people can maintain physiological metabolism by ingesting 6g linoleic acid every day. Linoleic acid combines with cholesterol, which is converted into cholic acid and steroids, thus preventing cholesterol from depositing on the blood vessel wall, reducing blood lipid and softening blood vessels. Phospholipids are essential brain-nourishing substances for the normal operation of human nervous system. The glycolipid contained in it has the functions of lowering blood sugar, lowering blood fat and resisting tumor. The total content of unsaponifiable lipids in rice bran oil is 4.2%, especially the content of γ-oryzanol ranks first in all kinds of edible oils, which has important physiological functions, can prevent the deposition of cholesterol, reduce the contents of cholesterol and triglycerides in plasma, especially reduce the ratio of low-density lipoprotein to high-density lipoprotein (its high value indicates that it is easy to get heart disease), thus playing a role in preventing and treating cardiovascular and cerebrovascular diseases. The toxicological experiment of rukminid C. on rice bran oil shows that rice bran oil has no toxic side effects and is safe and reliable to human body. However, the carcinogenicity studies of Tamagawa M. et al. on humans and mice show that rice bran oil has no teratogenic effect. 2.2 Physiological functions and research status of the by-products of rice bran oil refining. The bran cake or meal left after rice bran oil extraction is the raw material for the production of phytin. Phytic acid (phytic acid) is produced by ion exchange of calcium magnesium phytate. Phytic acid can be used to prevent colon cancer and kidney calculi, reduce cholesterol, be used as anticoagulant, anti-phage infection agent, stabilizer of VB2, VC and VE, effectively treat acne, and be used as preservative for food such as oil and meat. Inositol is a high-pressure hydrolysis product of calcium magnesium phytate, which belongs to vitamin drugs and has obvious curative effect on hyperlipidemia, liver cirrhosis, fatty liver and hypercholesterolemia. Inositol is widely used in biochemical reagents, food fortifiers, health foods, advanced cosmetics and aquatic feed additives. Therefore, many deep-processed products of rice bran oil refining by-products have obvious pharmacological and clinical effects. 2.2. 1 oryzanol is a mixture of various fatty alcohols and ferulic acid esters, which has various physiological functions. Its main pharmacological and clinical effects are as follows: ① It has hormone-like effects on autonomic nervous system (which can exist and function independently). As a autonomic nerve regulator, it has a good effect on autonomic nerve dysfunction. ② It can decrease and increase total cholesterol, low density lipoprotein cholesteryl acid and high density ester protein cholesterol respectively; Has the effects of resisting hyperlipidemia and inhibiting cholesterol self-synthesis. ③ The activation energy (Ea) is relatively high, with Ea=33. 1KJ/mol (note: EA of VA =13.0 kj/mol ~ 30.5 kj/mol); The change rate of heating activity (Q 10) is low, and Q 10= 1.30 (Note: Q10 =1.1. The stability of anti-lipid oxidation is slightly lower than VE, but higher than VA..④ ④ It can regulate and improve gastrointestinal neurosis. ⑤ As a fat-soluble vitamin, it can promote the growth and reproduction of animals. 2.2.2 Vitamin E VE refers to eight naturally occurring fat-soluble nutrients, namely four homologues of α-,β-,γ-and δ-tocopherol (T) and four homologues of α-,β-,γ-and δ-tocotrienols (T3). Tocotrienols (T3) can effectively reduce serum cholesterol, especially low-density lipoprotein directly related to cardiovascular diseases. T3 is the most effective anti-aging antioxidant for free radical chain interruption. T3 is also a good antithrombotic agent, and its function of inhibiting tumor growth is also attractive. 2.2.3 50% ~ 60% of the total hydrocarbon content in the deep-processed products of hydrocarbon and sterol rice bran oil refining by-products is squalene, which has physiological activities such as lowering blood fat and cholesterol. At the same time, it also contains phytosterol, which has the physiological function of synthesizing steroid hormones that regulate the metabolism of water, protein, sugar and salt. Phytosterols, as drugs for treating cardiovascular diseases, skin squamous cell carcinoma and intractable ulcers, have been applied or are undergoing clinical trials. It can also be used as raw materials for oral contraceptives and steroid drugs for the treatment of hypertension. In the cosmetics industry, sterol is also a raw material. The function of cellulose in rice bran is a kind of cereal fiber with high biological value. In recent 10 years, dietary fiber in food has attracted great attention of nutritionists all over the world. It can prevent and control some diet-related diseases. Rice bran is rich in dietary fiber, especially dietary fiber containing soluble and insoluble fiber. Insoluble dietary fiber can reduce the transportation time of meals in the body, while soluble dietary fiber can reduce serum cholesterol and affect the structural characteristics, gelling characteristics, thickening characteristics and emulsifying characteristics of foods. Moreover, rice bran is rich in other nutrients, which can be used as a source of functional cellulose and as a nutritional source in traditional foods without affecting the original flavor and tissue structure of foods. Rice bran cellulose contains 74 kinds of antioxidants, which can scavenge active oxygen free radicals in the body. It has a wide range of physiological functions and plays an important role in preventing and improving cardiovascular diseases caused by coronary atherosclerosis. It can inhibit and delay the absorption of cholesterol and triglycerides in lymph, and has stronger adsorption capacity than wheat bran cellulose. It also plays an important role in adsorbing harmful pesticides in human body and preventing liver cancer and colorectal cancer. There are many newly discovered vitamin E with strong physiological activity and many trace elements (zinc, selenium, magnesium, etc. ) cellulose in rice bran. Its functions: first, reduce blood lipid; Second, it can prevent cancer, promote intestinal peristalsis and facilitate defecation; Third, it can reduce plasma cholesterol and prevent cardiovascular diseases; Fourth, control obesity and improve immune function; Fifth, it is very important for the normal function of islet β cells, which can increase the secretion function, reduce the production of insulin antagonist hormones, restore the hypoglycemic effect of insulin, and prevent and treat diabetes. Rice bran cellulose (RBH) accounts for about 50% of rice bran fiber, which can be divided into water-soluble and alkali-soluble RBH. Because the content of water-soluble RBH in rice bran is relatively small, its development and application value is not great. Alkali-soluble RBH can be divided into RBHA (neutralization precipitation extraction) and RBHB (neutralization solution with ethanol extraction, also known as RBHB). RBHA is generally insoluble in water, with a large molecular weight, and its uronic acid content, viscosity, water holding capacity, swelling power and ion exchange capacity are lower than those of RBHB. Many studies have confirmed that rbh B has three physiological functions: inhibiting the increase of serum cholesterol, improving the intestinal environment and inhibiting the occurrence of colorectal cancer. At the end of 1980s, rbh B was produced on an industrial scale in Japan, which was mainly used for baked goods, ice cream and beverages (product development and application methods often appeared in the form of patents), and it was very popular in the Japanese market. 4. Functions and research status of rice bran vitamins and minerals 4. 1 rice bran vitamins Rice bran is rich in B vitamins and vitamin E, but lacks vitamin A and vitamin C. The contents of various vitamins in rice bran (mg/kg) are usually: VB 1 10 ~ 28, VB 66540 ~ 7, nicotinic acid 296 ~ 590. 4. 1. 1 rice bran VB 13 In Japan, the coarse rice bran cake was heated with methanol containing HAC, neutralized, and the methanol was removed by distillation. The residue was treated with acetone, then recrystallized, and the bactericide VB 13 crystal was prepared with acidic ion exchange resin. 4. 1.2 rice bran VB series syrup Japan successfully extracted vitamin B 1 from rice bran. The 100g hexane defatted rice bran contains not only VB 1L8 ~ 30mg, but also VB25.4~5.7mg, VB 4 19 ~ 32mg and VPP 308 ~. 4. 1.3 rice bran extract VE rice bran oil contains a certain amount of tocopherol, which is enriched in soapstock and deodorized distillate during crude oil refining. Soap residue is saponified with sodium hydroxide and ethanol solution, and then extracted with concentrated solution such as methanol, ethanol or acetone. After cooling and decoloring, a concentrated solution with tocopherol content of 10% ~ 15% can be obtained, and then a higher concentration of tocopherol can be obtained by molecular distillation. Natural tocopherol is superior to synthetic tocopherol in physiological activity and safety, which can prevent abnormal lipid metabolism, especially the production of lipid peroxide and membrane lipid aging in internal organs. Only natural tocopherol complex has nutritional and physiological functions to prevent human aging and prolong life. 4.2 Rice Bran Minerals In rice bran, P is the most mineral, followed by K, Mg and Se, the rest are Ca, Mn and Si, and Fe and Na are the lowest. P in rice bran mainly exists in phytic acid, nucleic acid and casein, among which P in phytic acid accounts for 89% of total P in rice bran. The mineral content (mg/kg) of rice bran ranges from 53 to 369, ca 250 ~ 13 10, fel 30 ~ 530, mg 860 ~ 12300, mnll 0 ~ 880 and p 6550. 4 2. 1 rice bran phytate calcium magnesium phytate, also known as calcium magnesium phytate, is a double salt formed by plants and calcium and magnesium ions, which widely exists in the inulin layer of plant seeds, especially in defatted rice bran, with the highest content of10% ~1%,so defatted rice bran cake is the best raw material for extracting calcium phytate. The extraction methods of calcium and magnesium phytate include alcohol precipitation, heavy metal separation, dilute acid extraction and alkali neutralization. Calcium phytate contains organic matter, calcium and other chemicals that can be easily absorbed by human body, which has unique physiological and pharmacological functions and is widely used. Calcium phytate can promote human metabolism and the growth and development of bone tissue, restore the balance of phosphorus in the body, be used for adjuvant treatment of neurasthenia, rickets, hand twitching, etc., and also relieve aluminum poisoning. In addition, it is also a raw material for extracting phytic acid and inositol. 4.2.2 Rice bran inositol Rice bran is the main raw material for extracting inositol. Inositol, also known as cyclohexanol, is a white crystalline or crystalline powder, odorless, slightly sweet, with a density of 1.752 and a melting point of 225 ~ 227℃. Insoluble in ethanol, ether and chloroform, the aqueous solution is neutral. It is a vitamin drug and a blood pressure lowering drug that is stable in the air. Besides being used as biochemical reagents, food additives and feed additives, it is also widely used in pharmaceutical industry. 4.2.3 Rice bran phytic acid phytic acid, also known as phytic acid, contains 28. 16% phosphorus, and is light yellow or light brown slurry liquid. Calcium phytate is often used as raw material to remove metal ions such as Na+, Mg2+, Ca2+ and mixed anions from double salt by ion exchange, and then decolorized by activated carbon and concentrated in vacuum. Phytic acid has strong chelation with Ca2+ in a wide pH range, which is the basis of its medical application. It can prevent and dissolve calcium precipitation in patients with various diseases, reduce calcium ion concentration in urine, and check the formation of kidney calculi. In pharmaceutical industry, phytic acid is one of the effective components in the production of riboflavin by fermentation. As a fermentation promoter, it can improve the yield of aminoglycoside antibiotics such as gentamicin; In medicine, special phytic acid colloid can be prepared for organ scintillation scanner; It can also be used as anticoagulant and anti-phage infection agent; Preventive agent for hyperbaric oxygen poisoning; Stabilizers such as VB2, VC and VE; Can inhibit the occurrence of colon cancer and effectively treat acne. In fact, different rice bran raw materials have different contents of vitamins and minerals, which is the result of their rice varieties, growing environment conditions, milling degree and rice bran shell content. Obviously, understanding this law has important practical significance. Because some vitamins and minerals in rice bran can be determined as quality control indicators of rice processing quality. Many rice bran products have much higher economic value than rice bran directly used as feed, such as rice germ oil, rice bran protein, rice bran protein beverage, inositol, oryzanol and so on. Many countries in the world, especially Japan, South Korea and some developed countries in Southeast Asia, have done a lot of research on the comprehensive utilization of rice bran, and China has also made great progress in the deep processing of rice bran in recent years. Rice bran is a potential high-quality food raw material. The functional active ingredients in rice bran are still under development, and new active ingredients will appear. In the process of understanding the functional components of rice bran, we should increase the industrial application of functional components and develop more and better high value-added products. It is believed that the functional components of rice bran will bring new vitality to all walks of life. Rice bran has high nutritional value and is the source of healthy food. A series of substances with health care function can be extracted. Functional oil, calcium phytate, oryzanol, phytic acid, inositol, vitamin B and vitamin E. These functional components have the functions of anti-tumor, reducing blood fat, lowering blood sugar, lowering cholesterol, sterilizing, diminishing inflammation and enhancing immunity. There are many deep processing technologies and methods of rice bran, and there are also many deep processing products of rice bran. Edible commercial rice bran (stable full-fat rice bran or defatted rice bran) can be used as primary products, and can also be further processed into secondary products of refined rice bran oil, rice bran protein hydrolysate, rice bran dietary fiber and other functional foods, as well as traditional foods with rice bran as raw materials, so as to increase efficiency and increase value. Using secondary products as raw materials, various new drugs can be produced, which are called tertiary products of rice bran processing. The development and utilization of rice bran has a wide range, deep level and great value-added potential, which may lead to fundamental changes in the traditional rice milling industry. In China, a country rich in rice bran resources, developing and popularizing rice bran stabilization technology suitable for China's national conditions, processing rice bran rationally and economically, using rice bran resources scientifically and in series, and developing first-,second-and third-grade products of rice bran processing with the guidance of international and domestic markets will increase the value of rice bran by dozens of times! This is not only conducive to the adjustment of rural industrial structure and the relief of grain and oil industry, but also a powerful measure to meet the challenges after China's entry into WTO and overcome the negative impact of global economic internationalization on China's underdeveloped agriculture and agricultural products processing industry. ◇