Rice bran oil rich in nutritional adjuncts and preparation method thereof

Abstract

The invention discloses rice bran oil rich in nutrient adjuncts and a preparation method of the rice bran oil, and belongs to the technical field of food and biochemical engineering. In the rice bran oil provided by the invention, the content of oryzanol is greater than or equal to 12000 mg / kg, and / or the content of free sterol is greater than or equal to 10000 mg / kg, and / or the content of vitamin E is greater than or equal to 200 mg / kg. The preparation method comprises the following steps: (1) mixing rice bran oil with the acid value of 10 mg KOH / g-25 mg KOH / g, alkali liquor and glycerol by using a high-speed shearing machine; (2) adding lipase accounting for 3%-10% of the weight of the rice bran oil, continuously filling inert gas in a vacuum state, and reacting for 0.5-6 hours; and (3) decoloring, deodorizing and degreasing to obtain the rice bran oil rich in nutrient adjuncts. The rice bran oil provided by the invention has the characteristics of high nutrient adjunct content, good stability, reasonable cost and the like, and the problems of obvious nutrient adjunct loss existing in chemical and physical refining and high production cost confronted by an enzymatic process are avoided. According to the preparation method provided by the invention, the process time is obviously shortened, the enzyme productivity is improved, and no organic solvent is used.

Description

Technical Field

[0001] This invention belongs to the fields of food and biochemical technology, and relates to a rice bran oil that efficiently retains oryzanol, vitamin E and free sterols and its preparation method. Specifically, it relates to a method that uses immobilized lipase to catalyze esterification and / or ester-ester exchange and / or acid hydrolysis reactions to reduce the free fatty acid content in rice bran oil while efficiently retaining oryzanol, vitamin E and free sterols. Background Technology

[0002] Rice bran oil is an oil prepared from rice bran, a byproduct of rice processing, through pressing and / or leaching, as well as refining. Saturated fatty acids and unsaturated fatty acids account for 15%–20% and 80%–85% of rice bran oil, respectively. Linoleic acid and oleic acid account for 38% and 42% respectively, with a near 1:1 ratio, conforming to the golden ratio recommended by the World Health Organization. Rice bran oil is rich in various active ingredients with nutritional and health benefits. For example, oryzanol can regulate nerves and relieve fatigue; vitamin E can eliminate free radicals, delay aging, and inhibit cancer cell production; squalene can regulate metabolism and protect the liver; and sterols can treat cardiovascular diseases and have anti-inflammatory effects.

[0003] Currently, the commonly used deacidification methods in rice bran oil processing are mainly chemical alkali refining and physical deacidification. Although chemical deacidification is the most suitable and direct process to obtain odorless, good-colored, and highly stable rice bran oil, it suffers from high operating costs, high refining consumption, high energy consumption, large waste emissions, and significant loss of nutrients such as oryzanol due to high oil loss and soapstock formation during the neutralization process. Physical deacidification yields relatively higher finished oil and results in less loss of active ingredients, but it cannot guarantee the quality of rice bran oil. Moreover, it usually requires that the phosphorus content in the oil before deodorization be less than 10 mg / kg and the metal content be less than 0.2 mg / kg. Often, due to the difficulty in completely removing gums and impurities, the refined rice bran oil has poor taste and color, high energy consumption, and forms trans fatty acids. In addition, the technology of reducing free fatty acid content by chemical catalytic esterification is feasible, but it has high equipment requirements and high process costs; solvent extraction deacidification faces problems such as large solvent consumption, food safety risks of solvent residue in the product, increased equipment investment due to the need for explosion-proof equipment, and the consumption of a large amount of energy for solvent removal; supercritical fluid extraction deacidification process is relatively expensive and is only suitable for expensive high acid value specialty oils or when the quality and purity of the extract are particularly important.

[0004] Enzymatic reduction of free fatty acids utilizes the esterification reaction between free fatty acids and acyl acceptors to convert free fatty acids into esters, thereby reducing the content of free fatty acids. This avoids the direct removal of free fatty acids in chemical alkali refining and physical deacidification methods, and can significantly improve the yield of rice bran oil.

[0005] Bhattacharyya et al. reported using sources fromMucor miehei Lipase can reduce the free fatty acid content in rice bran oil from 30% to 3.6% when esterification is carried out under the conditions of 10% water addition, 10% enzyme addition, 70°C and vacuum. However, the triglyceride and diglyceride contents in the product are 80.3% and 12.8% respectively, and subsequent operations still require chemical alkali refining to remove free fatty acids (Bhattacharyya, S., Bhattacharyya, DK, 1989. Biorefining of high acid rice bran oil. J. Am. Oil Chem. Soc. 66 (12), 1809–1811. https: / / doi.org / 10.1007 / BF02660752).

[0006] Ma Chuanguo et al. reported that catalytic esterification of rice bran oil using Lipozyme TL IM at 65°C, 9.3 h reaction time, 10% catalyst addition, 150% monoglyceride and glycerol addition, and a 1:1 ratio of monoglyceride and glycerol could reduce the acid value of rice bran oil from 43.0 mg / g to 7.2 mg / g. However, the reaction time was long and the acid value was high, and subsequent operations still required chemical alkali refining (Ma Chuanguo, Pan Siyi, Wang Gaolin, Wang Dezhi. 2011. Study on enzymatic esterification and deacidification of rice bran oil. Chinese Journal of Cereals and Oils, 26(3), 41–47).

[0007] Song et al. reported that using Lipozyme RM IM at 56°C, 5.75 h, 4.77% catalyst, and a monoglyceride to rice bran oil ratio of 0.25:1, the free fatty acid content in rice bran oil could be reduced to 0.28%, but the diglyceride content was as high as 27.98% (Song, Z., Liu, Y., Jin, Q., Li, L., Wang, X., Huang, J., & Liu, R. 2012. Lipase-catalyzed preparation of diacylglycerol-enriched oil from high-acid rice bran oil in solvent-free system. Applied Biochemistry Biotechnology, 168, 364–374. https: / / doi.org / 10.1007 / s12010-012-9780-y).

[0008] CN 114736739 B discloses a method for simultaneous enzymatic deacidification and functional lipid preparation using monoglycerides and other substances as acyl acceptors. The method involves mixing a water-absorbing agent such as molecular sieve with an immobilized enzyme and filling it into a reaction column. However, once the water-absorbing agent becomes saturated with water, the dehydration efficiency is significantly reduced. Furthermore, the water-absorbing agent and the immobilized enzyme are difficult to separate, resulting in low enzyme productivity and high enzyme usage costs.

[0009] CN 102318686 A and CN 104327954 A disclose a method for simultaneous enzymatic deacidification and preparation of sterol esters using sterols as acyl acceptors. However, the method has problems such as significant loss of activity due to lipase recovery and difficulty in collecting functional components. In addition, the immobilized enzyme has low catalytic efficiency during deacidification, resulting in a long reaction time and increased production costs. Furthermore, the use of organic solvents poses safety hazards.

[0010] CN 119061083 A discloses a method for simultaneous enzymatic deacidification and preparation of diglycerides using glycerol as an acyl acceptor. However, mechanical stirring can easily damage the immobilized support structure, thereby affecting the enzyme's catalytic activity and stability, increasing the cost of using the enzyme, and the immobilized enzyme has low catalytic efficiency.

[0011] CN 119709395 A discloses a gas-liquid-solid three-phase fluidized bed reactor and a method for simultaneous enzymatic deacidification and diglyceride preparation using the reactor. However, in the simultaneous deacidification and diglyceride preparation of high-acid-value rice bran oil, dewaxing is not performed, which affects the productivity of the immobilized enzyme.

[0012] CN 105802730 A discloses an enzymatic deacidification method using glycerol as an acyl acceptor, but the incoordination of vacuum degree, reaction temperature and reaction system surface-to-body ratio results in a high acid value and long reaction time, and a relatively low oryzanol retention rate. Moreover, the productivity of lipase was not evaluated under these conditions, which makes its actual application cost face many uncertainties.

[0013] CN 106566658 A discloses a method for esterification and deacidification catalyzed by glycerol-based lipase SMG1, which uses glycerol as an acyl acceptor, to reduce the free fatty acid content in rice bran oil from 25.6% to 1.42%. However, subsequent operations still require chemical deacidification, and the separation of liquid enzymes from oils is difficult, increasing investment in equipment such as centrifuges and processing difficulty.

[0014] CN 108611177 A discloses a type of rice bran oil with a content of ≥10000 mg / kg of oryzanol, ≥10000 mg / kg of sterol, and ≥400 mg / kg of vitamin E, but it needs to be prepared by externally adding oryzanol, sterol, and vitamin E.

[0015] Currently, conventional chemical and physical preparation technologies for rice bran oil face problems such as severe loss of accompanying nutrients, low product yield, and high energy consumption. Enzymatic preparation technologies mainly focus on enzyme screening and immobilization, selection of acyl acceptors and dehydrating agents, etc. There is an urgent need to provide a rice bran oil rich in accompanying nutrients and its preparation method. Summary of the Invention

[0016] Based on the existing problems in rice bran oil products and preparation technologies, this invention provides a rice bran oil rich in nutrient byproducts and its preparation method. The natural nutrient byproducts of rice bran oil are efficiently retained, the yield is high and the byproducts are few. The preparation method has the characteristics of high enzyme productivity, low production cost, no use of organic solvents, easy separation of product and enzyme, and suitability for continuous large-scale production.

[0017] To achieve the above technical solution, the technical solution of the present invention is as follows: A rice bran oil rich in nutritional byproducts, having a oryzanol content ≥12000 mg / kg, and / or a free sterol content ≥10000 mg / kg, and / or a vitamin E content ≥200 mg / kg; an acid value of 0.02 ~ 0.20 mg KOH / g, preferably 0.06 ~ 0.14 mg KOH / g, more preferably 0.08 ~ 0.12 mg KOH / g, and a peroxide value of 0 ~ 5.00 mmol / kg, preferably 0.02 ~ 2.00 mmol / kg, more preferably 0.05 ~ 0.10 mmol / kg.

[0018] The oryzanol content is 12,000 to 21,000 mg / kg, preferably 12,000 to 18,000 mg / kg, more preferably 15,000 to 18,000 mg / kg, and / or the free sterol content is 10,000 to 16,000 mg / kg, preferably 12,000 to 15,000 mg / kg, more preferably 14,000 to 15,000 mg / kg, and / or the vitamin E content is 200 to 390 mg / kg, preferably 250 to 360 mg / kg, more preferably 300 to 350 mg / kg.

[0019] A method for preparing the above-mentioned rice bran oil includes the following steps: (1) Rice bran oil, alkali solution and acyl acceptor are mixed using a high-speed shear machine and the temperature is adjusted to be no lower than the reaction temperature to obtain the first oil solution; (2) Add 3% to 10% of the weight of rice bran oil lipase to the first oil solution to obtain the second oil solution; (3) The second oil is continuously purged with inert gas at the reaction temperature and under vacuum for 0.5 to 6 hours to obtain the third oil; (4) The third oil is subjected to decolorization, deodorization and degreasing treatment in sequence to obtain rice bran oil rich in nutrients.

[0020] In step (1), the rice bran oil is pretreated by degumming and dewaxing, with an acid value of 10-25 mg KOH / g, a phosphorus content of less than 10 mg / kg, and a wax content of less than 0.1%. The alkaline solution is a sodium hydroxide or potassium hydroxide solution with an alkaline concentration of 2-10 mol / L, preferably 4 mol / L; the amount of alkaline added is 5-210 mg / kg, preferably 50-210 mg / kg, based on the weight of rice bran oil; the acyl acceptor includes glycerol, monoglyceride, and sterol, preferably glycerol; the molar ratio of the acyl acceptor to the free fatty acids in rice bran oil is 1:(2-4), preferably 1:(1.92-3).

[0021] In step (1), rice bran oil, alkali solution and acyl acceptor are mixed using a high-speed shear machine at a rate of 8000 ~ 21000 rpm and a time of 0.5 ~ 3 minutes, preferably 10000 ~ 16000 rpm and 0.5 minutes.

[0022] The lipase is derived from any one of the following microorganisms: Thermomyces lanuginosus, Rhizopus oryzae, Rhizomucor miehei, Candida antarctica, Aspergillus niger, and Candida dactylus, or a genetically modified strain thereof.

[0023] The lipase is an immobilized lipase, and the amount added is 3 to 10% of the weight of rice bran oil, preferably 5 to 10%. The immobilized lipase is selected from Lipozyme 435, CalB immo Plus, Addzyme CALB 165G, Lipozyme RMCN, and Lipozyme TL IM.

[0024] In step (3), the reaction temperature is 60 ~ 82°C; the vacuum state is an absolute pressure of 200 ~ 450 mbar; the inert gas is nitrogen or helium with a purity greater than 99.99%, preferably nitrogen which is readily available and has a controllable price; and the reaction time is 1 ~ 6 hours.

[0025] The process involves separating the third oil solution from the immobilized lipase via a bottom filter screen of the reactor before decolorization, deodorization, and degreasing, and then further filtering it through an external bag filter. The decolorization process conditions are: temperature 105-107°C, vacuum 0.09-0.1 MPa, decolorization time 25-30 min, clay addition of 2.5-4.0% of the oil weight, and activated carbon addition of 0.2%-0.4%. The deodorization process conditions are: oil temperature 245-255°C, absolute pressure not exceeding 200 Pa. The degreasing process conditions are: crystal growth tank 0-5°C, crystal growth for 72 hours followed by filtration.

[0026] The enzymatic method for reducing free fatty acids, characterized by system pH, temperature, time, pressure, and aeration volume, can achieve an enzyme productivity of no less than 4 tons / kg, preferably 4 to 5 tons / kg, and more preferably 4 to 4.5 tons / kg.

[0027] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention provides a rice bran oil rich in nutritional byproducts, namely oryzanol 12000 ~ 18000 mg / kg, and / or sterol 12000 ~ 15000 mg / kg, and / or vitamin E 250 ~ 360 mg / kg, which can achieve efficient retention of natural nutritional byproducts without the need for exogenous addition.

[0028] (2) In a solvent-free system, the present invention utilizes immobilized lipase to catalyze the esterification reaction between degummed and dewaxed rice bran oil and glycerol for 4 hours and 6 hours, which can reduce the free fatty acid content to below 0.70% and 0.20% respectively, with deacidification rates of 92.17% and 98.94% and triglyceride content above 92%. Subsequent conventional deodorization treatment can achieve the first-grade rice bran oil standard, and the immobilized lipase and product are easily separated.

[0029] (3) The present invention utilizes the pH of the alkaline solution to construct a suitable enzyme catalytic environment, which can significantly improve the catalytic activity and catalytic stability of immobilized lipase, and the enzyme productivity reaches 4~6 tons / kg, which is significantly higher than the 0.4~1.0 tons / kg of the currently reported enzymatic deacidification technology (based on an enzyme addition of 5%, 20~50 batches of recycling, and a free fatty acid content of less than 1.00% in the treated product).

[0030] (4) Based on the technical characteristics of immobilized lipase catalyzing esterification reaction to reduce free fatty acid content, this invention constructs an enzymatic method for reducing free fatty acid with characteristics such as system pH, surface-to-body ratio, temperature, time, pressure, and aeration volume. It has the advantages of low temperature, short time, less enzyme, small vacuum, and large processing capacity. Detailed Implementation

[0031] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] This invention provides a method for preparing rice bran oil rich in nutritional byproducts, comprising the following steps: (1) Rice bran oil, alkaline solution and acyl acceptor are mixed using a high-speed shear machine and the temperature is adjusted to be no lower than the reaction temperature to obtain the first oil solution; In this step, rice bran oil can be obtained using existing processes. For example, after pretreatment processes such as puffing, a mixed oil is obtained by leaching with n-hexane, and then the solvent is recovered by high-temperature vacuum evaporation to obtain crude rice bran oil. After degumming and dewaxing, the crude rice bran oil has an acid value of 10-25 mg KOH / g, a phosphorus content of <10 mg / kg, and a wax content of <0.1%. Based on the weight of the degummed and dewaxed rice bran oil, an alkaline solution with a concentration of 2-10 mol / L is added at a rate of 5-200 mg / kg. Based on the free fatty acids in the degummed and dewaxed rice bran oil, it is added to the mixture of degummed and dewaxed rice bran oil and alkaline solution at a molar ratio of acyl acceptors to free fatty acids of 1:2-4. The mixture is preheated to 1°C higher than the reaction temperature (60-80°C). (2) Add immobilized lipase to the first oil solution at 3% to 10% of the weight of the degummed and dewaxed rice bran oil to obtain the second oil solution; In this step, the immobilized lipase can be added using either a dry or wet method, with a wet method being preferred to avoid potential risks such as mechanical damage to the immobilized lipase and dust contamination causing allergies to operators. The lipase can be any one of the following microorganisms: *Thermomyces lanuginosus*, *Rhizopus oryzae*, *Rhizomucor miehei*, *Candida antarctica*, *Aspergillus niger*, and *Candida rugosa*, or a genetically modified strain thereof. The amount of lipase added is 3-10% of the total weight of the degummed and dewaxed rice bran oil, preferably 4-8%, more preferably 5-6%. Commercially available immobilized lipases include Lipozyme 435, CalB immo Plus, Addzyme CALB 165G, Lipozyme RM CN, and Lipozyme TL IM.

[0033] Among them, Lipozyme 435: from Candida antarctica and expressed in Aspergillus niger; Lipozyme RM CN: from Rhizomucor miehei and expressed in an Aspergillusoryzae; Lipzyme TL IM: from Thermomyces lanuginosus and expressed in an Aspergillus oryzae; CalB immo Plus: from Candida antarctica and expressed in Pichia pastoris; Addzyme CALB 165G: from Candida antarctica and expressed in Aspergillus niger.

[0034] Among them, Lipozyme 435, Lipozyme RM CN, and Lipozyme TL IM were purchased from Novozymes (China) Biotechnology Co., Ltd., CalB immo Plus was purchased from Purolite (China) Co., Ltd., and Addzyme CALB 165G was purchased from Advanced Enzyme Technologies Ltd. in India. (3) The reaction is carried out under set temperature and pressure for 0.5 to 6 hours to obtain the third oil; In this step, the reaction temperature is set to 60-80°C, preferably 65-75°C, and more preferably 67-72°C. The vacuum state is set to an absolute pressure of 200-450 mbar, preferably 250-400 mbar, and more preferably 275-325 mbar. The inert gas is nitrogen or helium with a purity greater than 99.99%, preferably readily available and inexpensive nitrogen. The reaction time is 0.5-6 hours, preferably 1-5 hours, and more preferably 2-4 hours.

[0035] (4) The third oil is then subjected to decolorization, deodorization and degreasing treatments to obtain rice bran oil rich in nutrients.

[0036] In this step, the third oil, before decolorization, deodorization, and degreasing, is separated from the immobilized lipase by a filter at the bottom of the reactor and then filtered again by an external bag filter. Decolorization process conditions: temperature 105~107°C, vacuum 0.09~0.1 MPa, decolorization time 25~30 min, bleaching clay addition 2.5~4.0% of oil weight, activated carbon addition 0.2%~0.4%. Deodorization process conditions: oil temperature 245~255°C, absolute pressure not exceeding 200 Pa. Degreasing process conditions: crystal growth tank 0~5°C, crystal growth for 72 hours followed by filtration.

[0037] The immobilized lipase is selected from Lipozyme 435, CalB immo Plus, Addzyme CALB 165G, Lipozyme RM CN, and Lipozyme TL IM. Example 1

[0038] This embodiment provides a method for preparing rice bran oil rich in nutritional byproducts, including the following steps: (1) Weigh 200 g of dewaxed and degummed rice bran oil (acid value of 16.99 ± 0.20 mg KOH / g) preheated to 73°C into a 500 mL reactor. Add 1.85 g of glycerol and then use a high-speed shear mixer to shear and mix at a rate of 10000 rpm for 0.5 minutes. Continue shearing and mixing for another 0.5 minutes and then add 62.5 μL of sodium hydroxide solution with a concentration of 4 mol / L.

[0039] (2) After adding 10 g of immobilized lipase Lipozyme 435, the reactor was sealed, the vacuum pump was started, nitrogen was introduced, and the pressure in the reactor was adjusted to stabilize at about 300 mbar. The reactor was kept at 72°C for 6 hours. After the reaction was completed, the immobilized lipase and rice bran oil (acid value of 0.36 ± 0.11 mg KOH / g) were separated by vacuum filtration.

[0040] (3) Add bleaching clay and activated carbon at 3.0% and 0.3% of the weight of the obtained rice bran oil, respectively, and decolorize for 30 min at 107°C and 0.1 MPa vacuum. Deodorize for 2 hours at 250°C and an absolute pressure not exceeding 200 Pa. After crystallizing in a crystallization tank at 5°C for 72 hours, filter to obtain rice bran oil rich in nutrients and byproducts. The acid value is 0.02 mg KOH / g, the peroxide value is 0.00 mmol / kg, and the contents of oryzanol, sterol and vitamin E are 18600 mg / kg, 15000 mg / kg and 380 mg / kg, respectively. The induction time is increased from 14.6 hours for degummed and dewaxed rice bran oil to 22.8 hours. Example 2

[0041] This embodiment provides a method for preparing rice bran oil rich in nutritional byproducts, including the following steps: (1) Weigh 200 g of dewaxed and degummed rice bran oil (acid value of 16.99 ± 0.20 mg KOH / g) preheated to 73°C into a 500 mL reactor. Add 1.85 g of glycerol and then use a high-speed shear mixer to shear and mix at a rate of 10000 rpm for 0.5 minutes. Continue shearing and mixing for another 0.5 minutes and then add 62.5 μL of sodium hydroxide solution with a concentration of 4 mol / L.

[0042] (2) After adding 10 g of immobilized lipase CalB Immo Plus, the reactor was sealed, the vacuum pump was started, nitrogen was introduced, and the pressure in the reactor was adjusted to stabilize at about 300 mbar. The reactor was kept at 72°C for 6 hours. After the reaction was completed, the immobilized lipase and rice bran oil (acid value of 0.87 ± 0.25 mg KOH / g) were separated by vacuum filtration.

[0043] (3) Add bleaching clay and activated carbon at 3.0% and 0.3% of the weight of the obtained rice bran oil, respectively, and decolorize for 30 min at 106°C and 0.1 MPa vacuum. Deodorize for 2 hours at 245°C and an absolute pressure not exceeding 200 Pa. After crystallizing in a crystallization tank at 5°C for 72 hours, filter to obtain rice bran oil rich in nutrients and byproducts. The acid value is 0.04 mg KOH / g, the peroxide value is 0.20 mmol / kg, and the contents of oryzanol, sterol and vitamin E are 16600 mg / kg, 15000 mg / kg and 360 mg / kg, respectively. The induction time is increased from 14.6 hours for degummed and dewaxed rice bran oil to 22.2 hours. Example 3

[0044] This embodiment provides a method for preparing rice bran oil rich in nutritional byproducts, including the following steps: (1) Weigh 200 g of dewaxed and degummed rice bran oil (acid value of 16.99 ± 0.20 mg KOH / g) preheated to 73°C into a 500 mL reactor. Add 1.85 g of glycerol and then use a high-speed shear mixer to shear and mix at a rate of 10000 rpm for 0.5 minutes. Continue shearing and mixing for another 0.5 minutes and then add 62.5 μL of sodium hydroxide solution with a concentration of 4 mol / L.

[0045] (2) After adding 10 g of immobilized lipase Addzyme CALB 165G, the reactor was sealed, the vacuum pump was started, nitrogen was introduced, and the pressure in the reactor was adjusted to stabilize at about 300 mbar. The reactor was kept at 72°C for 6 hours. After the reaction was completed, the immobilized lipase and rice bran oil (acid value of 0.46 ± 0.07 mg KOH / g) were separated by vacuum filtration.

[0046] (3) Add bleaching clay and activated carbon at 3.0% and 0.3% of the weight of the obtained rice bran oil, respectively, and decolorize for 30 min at 105°C and 0.1 MPa vacuum. Deodorize for 2 hours at 255°C and an absolute pressure not exceeding 200 Pa. After crystallizing in a crystallization tank at 5°C for 72 hours, filter to obtain rice bran oil rich in nutrients and byproducts. The acid value is 0.04 mg KOH / g, the peroxide value is 0.15 mmol / kg, and the contents of oryzanol, sterol and vitamin E are 17600 mg / kg, 145000 mg / kg and 330 mg / kg, respectively. The induction time is increased from 14.6 hours for degummed and dewaxed rice bran oil to 20.9 hours. Example 4

[0047] This embodiment provides a method for preparing rice bran oil rich in nutritional byproducts, including the following steps: (1) Weigh 200 g of dewaxed and degummed rice bran oil (acid value of 16.99 ± 0.20 mg KOH / g) preheated to 73°C into a 500 mL reactor. Add 1.85 g of glycerol and then use a high-speed shear mixer to shear and mix at a rate of 10000 rpm for 0.5 minutes. Continue shearing and mixing for another 0.5 minutes and then add 62.5 μL of sodium hydroxide solution with a concentration of 4 mol / L.

[0048] (2) After adding 10 g of immobilized lipase Lipozyme 435, the reactor was sealed, the vacuum pump was started, nitrogen was introduced, and the pressure in the reactor was adjusted to stabilize at about 300 mbar. The reactor was kept at 72°C for 4 hours. After the reaction was completed, the immobilized lipase and rice bran oil (acid value of 1.33 ± 0.11 mg KOH / g) were separated by vacuum filtration.

[0049] (3) Add bleaching clay and activated carbon at 3.0% and 0.3% of the weight of the obtained rice bran oil, respectively, and decolorize for 30 min at 105°C and 0.1 MPa vacuum. Deodorize for 2 hours at 245°C and an absolute pressure not exceeding 200 Pa. After crystallizing in a crystallization tank at 5°C for 72 hours, filter to obtain rice bran oil rich in nutrients and byproducts. The acid value is 0.05 mg KOH / g, the peroxide value is 0.15 mmol / kg, and the contents of oryzanol, sterol and vitamin E are 19600 mg / kg, 16000 mg / kg and 390 mg / kg, respectively. The induction time is increased from 14.6 hours for degummed and dewaxed rice bran oil to 23.2 hours. Example 5

[0050] This embodiment provides a method for preparing rice bran oil rich in nutritional byproducts, including the following steps: (1) Weigh 200 g of dewaxed and degummed rice bran oil (acid value of 16.99 ± 0.20 mg KOH / g) preheated to 73°C into a 500 mL reactor, add 11.26 g of oleic acid monoglyceride, and then use a high-speed shear mixer to shear and mix at a rate of 10000 rpm for 0.5 minutes. During the shear and mix process for another 0.5 minutes, add 62.5 μL of sodium hydroxide solution with a concentration of 4 mol / L.

[0051] (2) After adding 10 g of immobilized lipase Lipozyme 435, the reactor was sealed, the vacuum pump was started, nitrogen was introduced, and the pressure in the reactor was adjusted to stabilize at about 300 mbar. The reactor was kept at 72°C for 6 hours. After the reaction was completed, the immobilized lipase and rice bran oil (acid value of 0.33 ± 0.03 mg KOH / g) were separated by vacuum filtration.

[0052] (3) Add bleaching clay and activated carbon at 3.0% and 0.3% of the weight of the obtained rice bran oil, respectively, and decolorize for 30 min at 105°C and 0.1 MPa vacuum. Deodorize for 2 hours at 245°C and an absolute pressure not exceeding 200 Pa. After crystallizing in a crystallization tank at 5°C for 72 hours, filter to obtain rice bran oil rich in nutrients and byproducts. The acid value is 0.05 mg KOH / g, the peroxide value is 0.10 mmol / kg, and the contents of oryzanol, sterol and vitamin E are 18200 mg / kg, 15300 mg / kg and 350 mg / kg, respectively. The induction time is increased from 14.6 hours for degummed and dewaxed rice bran oil to 17.6 hours. Example 6

[0053] An example provides a method for preparing rice bran oil rich in nutritional byproducts, comprising the following steps: (1) Weigh 200 g of dewaxed and degummed rice bran oil (acid value of 23.11 ± 0.13 mg KOH / g) preheated to 73°C into a 500 mL reactor. Add 3.03 g of glycerol and use a high-speed shear mixer to shear and mix at a rate of 10000 rpm for 0.5 minutes. Continue shearing and mixing for another 0.5 minutes and add 62.5 μL of sodium hydroxide solution with a concentration of 4 mol / L.

[0054] (2) After adding 10 g of immobilized lipase Lipozyme 435, the reactor was sealed, the vacuum pump was started, nitrogen was introduced, and the pressure in the reactor was adjusted to stabilize at about 300 mbar. The reactor was kept at 72°C for 6 hours. After the reaction was completed, the immobilized lipase and rice bran oil (acid value of 1.58 ± 0.22 mg KOH / g) were separated by vacuum filtration.

[0055] (3) Add bleaching clay and activated carbon at 3.0% and 0.3% of the weight of the obtained rice bran oil, respectively, and decolorize for 30 min at 105°C and 0.1 MPa vacuum. Deodorize for 2 hours at 245°C and an absolute pressure not exceeding 200 Pa. After crystallizing in a crystallization tank at 5°C for 72 hours, filter to obtain rice bran oil rich in nutrients and byproducts. The acid value is 0.05 mg KOH / g, the peroxide value is 0.20 mmol / kg, and the contents of oryzanol, sterol and vitamin E are 18100 mg / kg, 15300 mg / kg and 360 mg / kg, respectively. Example 7

[0056] This embodiment provides a method for preparing rice bran oil rich in nutritional byproducts, including the following steps: (1) Weigh 200 g of dewaxed and degummed rice bran oil (acid value of 23.11 ± 0.13 mg KOH / g) preheated to 73°C into a 500 mL reactor. Add 2.53 g of glycerol and use a high-speed shear mixer to shear and mix at a rate of 8000 rpm for 0.5 minutes. Continue shearing and mixing for another 0.5 minutes and add 31.8 μL of sodium hydroxide solution with a concentration of 4 mol / L.

[0057] (2) After adding 10 g of immobilized lipase Lipozyme 435, the reactor was sealed, the vacuum pump was started, nitrogen was introduced, and the pressure in the reactor was adjusted to stabilize at about 300 mbar. The reactor was kept at 72°C for 6 hours. After the reaction was completed, the immobilized lipase and rice bran oil (acid value of 3.38 ± 1.20 mg KOH / g) were separated by vacuum filtration.

[0058] (3) Add bleaching clay and activated carbon at 3.0% and 0.3% of the weight of the obtained rice bran oil, respectively, and decolorize for 30 min at 105°C and 0.1 MPa vacuum. Deodorize for 2 hours at 255°C and an absolute pressure not exceeding 200 Pa. After crystallizing in a crystallization tank at 5°C for 72 hours, filter to obtain rice bran oil rich in nutrients and byproducts. The acid value is 0.08 mg KOH / g, the peroxide value is 0.15 mmol / kg, and the contents of oryzanol, sterol and vitamin E are 18500 mg / kg, 15500 mg / kg and 370 mg / kg, respectively. Example 8

[0059] This embodiment provides a method for preparing rice bran oil rich in nutritional byproducts, including the following steps: (1) Weigh 200 g of dewaxed and degummed rice bran oil (acid value of 23.11 ± 0.13 mg KOH / g) preheated to 73°C into a 500 mL reactor. Add 2.53 g of glycerol and then use a high-speed shear mixer to shear and mix at a rate of 16000 rpm for 1 minute. Continue shearing and mixing for another minute and then add 131.2 μL of sodium hydroxide solution with a concentration of 4 mol / L.

[0060] (2) After adding 10 g of immobilized lipase Lipozyme 435, the reactor was sealed, the vacuum pump was started, nitrogen was introduced, and the pressure in the reactor was adjusted to stabilize at about 300 mbar. The reactor was kept at 72°C for 6 hours. After the reaction was completed, the immobilized lipase and rice bran oil (acid value of 2.46 ± 0.60 mg KOH / g) were separated by vacuum filtration.

[0061] (3) Add bleaching clay and activated carbon at 3.0% and 0.3% of the weight of the obtained rice bran oil, respectively, and decolorize for 30 min at 105°C and 0.1 MPa vacuum. Deodorize for 2 hours at 255°C and an absolute pressure not exceeding 200 Pa. After crystallizing in a crystallization tank at 5°C for 72 hours, filter to obtain rice bran oil rich in nutrients and byproducts. The acid value is 0.06 mg KOH / g, the peroxide value is 0.25 mmol / kg, and the contents of oryzanol, sterol and vitamin E are 14500 mg / kg, 12500 mg / kg and 280 mg / kg, respectively. Example 9

[0062] This embodiment provides a method for preparing rice bran oil rich in nutritional byproducts, including the following steps: (1) Weigh 200 g of dewaxed and degummed rice bran oil (acid value of 23.11 ± 0.13 mg KOH / g) preheated to 73°C into a 500 mL reactor. Add 2.53 g of glycerol and use a high-speed shear mixer to shear and mix at a rate of 21000 rpm for 1.5 minutes. Continue shearing and mixing for another 1.5 minutes and add 262.5 μL of sodium hydroxide solution with a concentration of 4 mol / L.

[0063] (2) After adding 10 g of immobilized lipase Lipozyme 435, the reactor was sealed, the vacuum pump was started, nitrogen was introduced, and the pressure in the reactor was adjusted to stabilize at about 300 mbar. The reactor was kept at 72°C for 6 hours. After the reaction was completed, the immobilized lipase and rice bran oil (acid value of 2.56 ± 0.59 mg KOH / g) were separated by vacuum filtration.

[0064] (3) Add bleaching clay and activated carbon at 3.0% and 0.3% of the weight of the obtained rice bran oil, respectively, and decolorize for 30 min at 105°C and 0.1 MPa vacuum. Deodorize for 2 hours at 255°C and an absolute pressure not exceeding 200 Pa. After crystallizing in a crystallization tank at 5°C for 72 hours, filter to obtain rice bran oil rich in nutrients and byproducts. The acid value is 0.12 mg KOH / g, the peroxide value is 0.25 mmol / kg, and the contents of oryzanol, sterol and vitamin E are 12000 mg / kg, 10100 mg / kg and 210 mg / kg, respectively. Example 10

[0065] This embodiment provides a method for preparing rice bran oil rich in nutritional byproducts, including the following steps: (1) Weigh 200 g of dewaxed and degummed rice bran oil (acid value of 23.11 ± 0.13 mg KOH / g) preheated to 63°C into a 500 mL reactor. Add 2.53 g of glycerol and then use a high-speed shear mixer to shear and mix at a rate of 12000 rpm for 0.5 minutes. Continue shearing and mixing for another 0.5 minutes and then add 62.5 μL of sodium hydroxide solution with a concentration of 4 mol / L.

[0066] (2) After adding 10 g of immobilized lipase Lipozyme 435, the reactor was sealed, the vacuum pump was started, nitrogen was introduced, and the pressure in the reactor was adjusted to stabilize at about 300 mbar. The reactor was kept at 62°C and the reaction time was recorded for 6 hours. After the reaction was completed, the immobilized lipase and rice bran oil (acid value of 6.98 ± 0.30 mg KOH / g) were separated by vacuum filtration.

[0067] (3) Add bleaching clay and activated carbon at 3.0% and 0.3% of the weight of the obtained rice bran oil, respectively, and decolorize for 30 min at 105°C and 0.1 MPa vacuum. Deodorize for 3 hours at 255°C and an absolute pressure not exceeding 200 Pa. After crystallizing in a crystallization tank at 5°C for 72 hours, filter to obtain rice bran oil rich in nutrients and byproducts. The acid value is 0.16 mg KOH / g, the peroxide value is 0.35 mmol / kg, and the contents of oryzanol, sterol and vitamin E are 13200 mg / kg, 11100 mg / kg and 230 mg / kg, respectively. Example 11

[0068] This embodiment provides a method for preparing rice bran oil rich in nutritional byproducts, including the following steps: (1) Weigh 200 g of dewaxed and degummed rice bran oil (acid value of 23.11 ± 0.13 mg KOH / g) preheated to 83°C into a 500 mL reactor. Add 2.53 g of glycerol and then use a high-speed shear mixer to shear and mix at a rate of 12000 rpm for 0.5 minutes. Continue shearing and mixing for another 0.5 minutes and then add 62.5 μL of sodium hydroxide solution with a concentration of 4 mol / L.

[0069] (2) After adding 10 g of immobilized lipase Lipozyme 435, the reactor was sealed, the vacuum pump was started, nitrogen was introduced, and the pressure in the reactor was adjusted to stabilize at about 300 mbar. The reactor was kept at 82°C for 6 hours. After the reaction was completed, the immobilized lipase and rice bran oil (acid value of 1.14 ± 0.12 mg KOH / g) were separated by vacuum filtration.

[0070] (3) Add bleaching clay and activated carbon at 3.0% and 0.3% of the weight of the obtained rice bran oil, respectively, and decolorize for 30 min at 105°C and 0.1 MPa vacuum. Deodorize for 2 hours at 255°C and an absolute pressure not exceeding 200 Pa. After crystallizing in a crystallization tank at 5°C for 72 hours, filter to obtain rice bran oil rich in nutrients and byproducts. The acid value is 0.03 mg KOH / g, the peroxide value is 0.15 mmol / kg, and the contents of oryzanol, sterol and vitamin E are 15500 mg / kg, 12700 mg / kg and 300 mg / kg, respectively. Example 12

[0071] This embodiment provides a method for preparing rice bran oil rich in nutritional byproducts, including the following steps: (1) Weigh 200 g of dewaxed and degummed rice bran oil (acid value of 23.11 ± 0.13 mg KOH / g) preheated to 73°C into a 500 mL reactor. Add 2.53 g of glycerol and then use a high-speed shear mixer to shear and mix at a rate of 12000 rpm for 0.5 minutes. Continue shearing and mixing for another 0.5 minutes and then add 62.5 μL of sodium hydroxide solution with a concentration of 4 mol / L.

[0072] (2) After adding 10 g of immobilized lipase Lipozyme 435, the reactor was sealed, the vacuum pump was started, nitrogen was introduced, and the pressure in the reactor was adjusted to stabilize at about 200 mbar. The reactor was kept at 72°C for 4 hours. After the reaction was completed, the immobilized lipase and rice bran oil (acid value of 2.60 ± 0.09 mg KOH / g) were separated by vacuum filtration.

[0073] (3) Add bleaching clay and activated carbon at 3.0% and 0.3% of the weight of the obtained rice bran oil, respectively, and decolorize for 30 min at 105°C and 0.1 MPa vacuum. Deodorize for 2 hours at 255°C and an absolute pressure not exceeding 200 Pa. After crystallizing in a crystallization tank at 5°C for 72 hours, filter to obtain rice bran oil rich in nutrients and byproducts. The acid value is 0.07 mg KOH / g, the peroxide value is 0.08 mmol / kg, and the contents of oryzanol, sterol and vitamin E are 16700 mg / kg, 13300 mg / kg and 266 mg / kg, respectively. Example 13

[0074] This embodiment provides a method for preparing rice bran oil rich in nutritional byproducts, including the following steps: (1) Weigh 200 g of dewaxed and degummed rice bran oil (acid value of 23.11 ± 0.13 mg KOH / g) preheated to 73°C into a 500 mL reactor. Add 2.53 g of glycerol and then use a high-speed shear mixer to shear and mix at a rate of 12000 rpm for 0.5 minutes. Continue shearing and mixing for another 0.5 minutes and then add 62.5 μL of sodium hydroxide solution with a concentration of 4 mol / L.

[0075] (2) After adding 20 g of immobilized lipase Lipozyme 435, the reactor was sealed, the vacuum pump was started, nitrogen was introduced, and the pressure in the reactor was adjusted to stabilize at about 450 mbar. The reactor was kept at 72°C for 6 hours. After the reaction was completed, the immobilized lipase and rice bran oil (acid value of 2.76 ± 0.37 mg KOH / g) were separated by vacuum filtration.

[0076] (3) Add bleaching clay and activated carbon at 3.0% and 0.3% of the weight of the obtained rice bran oil, respectively, and decolorize for 30 min at 105°C and 0.1 MPa vacuum. Deodorize for 2 hours at 255°C and an absolute pressure not exceeding 200 Pa. After crystallizing in a crystallization tank at 5°C for 72 hours, filter to obtain rice bran oil rich in nutrients and byproducts. The acid value is 0.06 mg KOH / g, the peroxide value is 0.13 mmol / kg, and the contents of oryzanol, sterol and vitamin E are 15800 mg / kg, 12900 mg / kg and 295 mg / kg, respectively. Example 14

[0077] This embodiment provides a method for preparing rice bran oil rich in nutritional byproducts, including the following steps: (1) Weigh 360 g of dewaxed and degummed rice bran oil (acid value of 23.11 ± 0.13 mg KOH / g) preheated to 73°C into a 500 mL reactor. Add 5.46 g of glycerol and use a high-speed shear mixer to shear and mix at a rate of 12000 rpm for 0.5 minutes. Continue shearing and mixing for another 0.5 minutes and add 112.5 μL of sodium hydroxide solution with a concentration of 4 mol / L.

[0078] (2) After adding 20 g of immobilized lipase Lipozyme 435, the reactor was sealed, the vacuum pump was started, nitrogen was introduced, and the pressure in the reactor was adjusted to stabilize at about 450 mbar. The reactor was kept at 72°C for 6 hours. After the reaction was completed, the immobilized lipase and rice bran oil (acid value of 3.63 ± 0.18 mg KOH / g) were separated by vacuum filtration.

[0079] (3) Add bleaching clay and activated carbon at 3.0% and 0.3% of the weight of the obtained rice bran oil, respectively, and decolorize for 30 min at 105°C and 0.1 MPa vacuum. Deodorize for 2 hours at 255°C and an absolute pressure not exceeding 200 Pa. After crystallizing in a crystallization tank at 5°C for 72 hours, filter to obtain rice bran oil rich in nutrients and byproducts. The acid value is 0.09 mg KOH / g, the peroxide value is 0.08 mmol / kg, and the contents of oryzanol, sterol and vitamin E are 16300 mg / kg, 13700 mg / kg and 325 mg / kg, respectively. Example 15

[0080] This embodiment provides a method for preparing rice bran oil rich in nutritional byproducts, including the following steps: (1) Weigh 200 g of dewaxed and degummed rice bran oil (acid value of 23.11 ± 0.13 mg KOH / g) preheated to 73°C into a 500 mL reactor. Add 2.53 g of glycerol and then use a high-speed shear mixer to shear and mix at a rate of 12000 rpm for 0.5 minutes. Continue shearing and mixing for another 0.5 minutes and then add 62.5 μL of sodium hydroxide solution with a concentration of 4 mol / L.

[0081] (2) After adding 2.50 g of immobilized lipase Lipozyme 435, the reactor was sealed, the vacuum pump was started, nitrogen was introduced, and the pressure in the reactor was adjusted to stabilize at approximately 300 mbar. The reactor was then kept at 72°C for 24 hours. After the reaction, the immobilized lipase and rice bran oil were separated by vacuum filtration, with an acid value of 0.35 ± 0.05 mg KOH / g. The operation was repeated 50 times, and the average acid value of the obtained rice bran oil was less than 2.0 mg KOH / g. The residual enzyme activity of the lipase can be mixed with fresh immobilized enzyme for use.

[0082] Comparative Example 1 This embodiment provides a method for preparing rice bran oil rich in nutritional byproducts, including the following steps: (1) Weigh 200 g of preheated dewaxed and degummed rice bran oil (acid value of 16.99 ± 0.20 mg KOH / g) into a 500 mL reactor, add 1.85 g of glycerol, and then use a high-speed shear mixer to shear and mix at a rate of 10000 rpm for 0.5 minutes. Continue shearing and mixing for another 0.5 minutes, and then add 62.50 μL of sodium hydroxide solution with a concentration of 4 mol / L.

[0083] (2) After adding 10 g of immobilized lipase Lipozyme 435, the reactor was sealed, the vacuum pump was started, nitrogen was introduced, and the pressure in the reactor was adjusted to stabilize at about 300 mbar. The reaction temperature was 50℃, and the reaction time was recorded for 6 hours. After the reaction was completed, the immobilized lipase and rice bran oil (acid value of 10.47 ± 0.06 mg KOH / g) were separated by vacuum filtration.

[0084] (3) Add bleaching clay and activated carbon at 3.0% and 0.3% of the weight of the obtained rice bran oil, respectively, and decolorize for 30 min at 105°C and 0.1 MPa vacuum. Deodorize for 2 hours at 245°C and an absolute pressure not exceeding 200 Pa. After crystallizing in a crystallization tank at 5°C for 72 hours, filter to obtain rice bran oil rich in nutrients and byproducts. The acid value is 0.15 mg KOH / g, the peroxide value is 0.20 mmol / kg, and the contents of oryzanol, sterol and vitamin E are 12600 mg / kg, 13000 mg / kg and 320 mg / kg, respectively. The induction time is increased from 14.6 hours for degummed and dewaxed rice bran oil to 15.1 hours.

[0085] Comparative Example 2 This embodiment provides a method for preparing rice bran oil rich in nutritional byproducts, including the following steps: (1) Weigh 200 g of dewaxed and degummed rice bran oil (acid value of 23.11 ± 0.13 mg KOH / g) preheated to 73°C into a 500 mL reactor, add 3.03 g of glycerol, and then use a high-speed shear mixer to shear and mix at a rate of 10000 rpm for 1 minute.

[0086] (1) After adding 10 g of immobilized lipase Lipozyme 435, the reactor was sealed, the vacuum pump was started, nitrogen was introduced, and the pressure in the reactor was adjusted to stabilize at about 300 mbar. The reaction time was recorded for 6 hours. After the reaction was completed, the immobilized lipase and rice bran oil (acid value of 2.74 ± 0.54 mg KOH / g) were separated by vacuum filtration.

[0087] (3) Add bleaching clay and activated carbon at 3.0% and 0.3% of the weight of the obtained rice bran oil, respectively, and decolorize for 30 min at 105°C and 0.1 MPa vacuum. Deodorize for 2 hours at 245°C and an absolute pressure not exceeding 200 Pa. After crystallizing in a crystallization tank at 5°C for 72 hours, filter to obtain rice bran oil rich in nutrients and byproducts. The acid value is 0.09 mg KOH / g, the peroxide value is 0.25 mmol / kg, and the contents of oryzanol, sterol and vitamin E are 18900 mg / kg, 15900 mg / kg and 380 mg / kg, respectively.

[0088] Comparative Example 3 This embodiment provides a method for preparing rice bran oil rich in nutritional byproducts, including the following steps: 200 g of preheated (73°C) dewaxed and degummed rice bran oil (acid value 23.11 ± 0.13 mg KOH / g) was weighed into a 500 mL reactor. 3.03 g of glycerol was added, and the mixture was sheared at 10,000 rpm for 1 minute using a high-speed shear mixer. 10 g of immobilized lipase Lipozyme 435 was added, the reactor was sealed, and a vacuum pump was started to maintain a pressure of approximately 300 mbar. The reaction was timed for 6 hours. After the reaction, the immobilized lipase and rice bran oil were separated by vacuum filtration. The acid value of the rice bran oil was 9.74 ± 0.34 mg KOH / g.

[0089] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the preferred embodiments have been described in detail, those skilled in the art can still make appropriate modifications or equivalent substitutions to the solutions of the present invention, and such modifications or substitutions should be considered to still fall within the spirit and scope of the technical solutions of the present invention.

Claims

1. A rice bran oil rich in nutritional byproducts, characterized in that, The content of oryzanol is ≥12000 mg / kg, and / or the content of free sterols is ≥10000 mg / kg, and / or the content of vitamin E is ≥200 mg / kg; the acid value is 0.02 ~ 0.20 mg KOH / g, and the peroxide value is 0 ~ 5.00 mmol / kg.

2. The rice bran oil according to claim 1, characterized in that, The content of oryzanol is 12,000 ~ 21,000 mg / kg, and / or the content of free sterol is 10,000 ~ 16,000 mg / kg, and / or the content of vitamin E is 200 ~ 390 mg / kg.

3. A method for preparing rice bran oil according to claim 1 or 2, characterized in that, Includes the following steps: (1) Rice bran oil, alkali solution and acyl acceptor are mixed using a high-speed shear machine and the temperature is adjusted to be no lower than the reaction temperature to obtain the first oil solution; (2) Add 3% to 10% of the weight of rice bran oil lipase to the first oil solution to obtain the second oil solution; (3) The second oil is continuously purged with inert gas at the reaction temperature and under vacuum for 0.5 to 6 hours to obtain the third oil; (4) The third oil is subjected to decolorization, deodorization and degreasing treatment in sequence to obtain rice bran oil rich in nutrients.

4. The preparation method according to claim 3, characterized in that, In step (1), the rice bran oil is pretreated by degumming and dewaxing, with an acid value of 10-25 mg KOH / g, a phosphorus content of less than 10 mg / kg, and a wax content of less than 0.1%.

5. The preparation method according to claim 3, characterized in that, In step (1), the alkaline solution is a sodium hydroxide or potassium hydroxide solution with an alkaline concentration of 2 to 10 mol / L; the amount of alkaline added is 5 to 200 mg / kg based on the weight of rice bran oil; the acyl receptors include glycerol, monoglycerides and sterols; the molar ratio of the acyl receptors to the free fatty acids in rice bran oil is 1:(2 to 4).

6. The preparation method according to claim 3, characterized in that, In step (1), rice bran oil, alkali solution and acyl acceptor are mixed using a high-speed shear machine at a rate of 8000 ~ 21000 rpm and a time of 0.5 ~ 3 minutes.

7. The preparation method according to claim 3, characterized in that, The lipase is derived from any one of the following microorganisms: Thermomyces lanuginosus, Rhizopus oryzae, Rhizomucor miehei, Candida antarctica, Aspergillus niger, and Candida rugosa, or a genetically modified strain thereof.

8. The preparation method according to claim 3, characterized in that, The lipase is an immobilized lipase, and the amount added is 3 to 10% of the weight of rice bran oil.

9. The preparation method according to claim 3, characterized in that, In step (3), the reaction temperature is 60 ~ 82°C; the vacuum state is an absolute pressure of 200 ~ 450 mbar; the inert gas is nitrogen or helium with a purity greater than 99.99%; and the reaction time is 1 ~ 6 hours.

10. The preparation method according to claim 4, characterized in that, Before the decolorization, deodorization, and degreasing treatments, the third oil solution is separated from the immobilized lipase by a filter screen at the bottom of the reactor and then filtered again by an external bag filter. The decolorization process conditions are: temperature 105 ~ 107°C, vacuum degree 0.09 ~ 0.1 MPa, decolorization time 25 ~ 30 min, bleaching clay addition of 2.5 ~ 4.0% of oil weight, and activated carbon addition of 0.2% ~ 0.4%. The deodorization process conditions are: oil temperature 245 ~ 255°C, absolute pressure not exceeding 200 Pa. The degreasing process conditions are: crystal growth tank 0 ~ 5°C, crystal growth for 72 hours and filtration.