Rice bran processing method and rice bran oil

Abstract

The present invention provides a processing method for rice bran, which includes the step of radio frequency heating the frozen rice bran. The crude oil obtained by extracting oil from the rice bran processed by the processing method of the present invention has the advantages of less gum and wax and light color, thereby reducing the difficulty of subsequent refining of the crude rice bran oil and reducing the loss of neutral oil and nutrients.

Description

Technical Field

[0001] The present invention belongs to the technical field of edible vegetable oil processing, relates to the preparation and processing of an oil product, and particularly relates to the preparation and processing of rice bran oil. Background Art

[0002] Rice bran oil is a vegetable oil with balanced fatty acids and high nutritional value, and is extracted and prepared from rice bran, a by-product of rice processing. The content of unsaturated fatty acids in rice bran oil is as high as 80%. At the same time, rice bran oil also contains bioactive substances such as oryzanol, fat-soluble vitamins, and phytosterols, and is a nutritionally healthy oil recognized at home and abroad.

[0003] Cao Xiaofeng (The influence of refining processes and storage conditions on the quality of high acid value rice bran oil, Wuhan Polytechnic University, 2014) studied the influence of each refining process on the quality of high acid value rice bran oil. After the crude rice bran oil was refined, its acid value, peroxide value, and color reached the national standards. In addition, some physiological active substances such as oryzanol, vitamin E, and phytosterols were also severely lost during the refining process. The loss of oryzanol was 93%, the loss of vitamin E was 58%, and the loss of phytosterols was 70%. This indicates that there is over-refining in the rice bran oil processing process.

[0004] Liu Yulan et al. (Liu Yulan, Zheng Laining, Wang Dongmin, etc., The influence of rice bran extrusion expansion on the quality of its crude oil and decolorization effect, Cereals & Oils, 2015, 28(8), 45-49) believe that under the extrusion expansion conditions of high temperature, high humidity, and high pressure, components such as proteins, phospholipids, and sugars in rice bran will interact or denature, resulting in the deepening of the color of rice bran and its crude oil. The extrusion expansion treatment can deepen the color of the extracted crude rice bran oil and the newly formed pigments are difficult to remove.

[0005] Radio frequency is a kind of high-frequency changing electromagnetic wave. Radio frequency heating relies on a rapidly changing electromagnetic field to cause the rapid rotation and friction of polar molecules inside the material, generating a thermal effect. Its action mechanism is similar to that of microwave (electromagnetic wave with a frequency of 300 - 3000 MHz), but radio frequency uses electromagnetic waves with a frequency of 3 kHz - 300 MHz. It is a whole-volume heating technology, with advantages such as rapid heating, large penetration depth, and good heating uniformity, and has received increasing attention in the field of food and agricultural product processing. Patent CN10724243A provides a method for stabilizing rice bran using a radio frequency heating device. The rice bran is fed onto the conveyor belt of the radio frequency heating system, moves along with the conveyor belt, and receives radio frequency irradiation to kill the enzymes contained in the rice bran, so as to achieve the purpose of stabilizing the rice bran. Patent CN10902212A discloses a processing method for extracting rice bran oil from heat-stable rice bran meal. Through steps such as radio frequency heating, enzymatic hydrolysis, jet cooking, and ultrasonic extraction of the rice bran, crude rice bran oil with good stability can be obtained. The above technologies mainly use radio frequency heating to inactivate lipase in rice bran to inhibit the hydrolysis of fat by lipase, but the effects on other qualities of the crude oil, such as impurity dissolution and color, are mostly negative.

[0006] The existing technology still lacks a preparation method for high-quality crude rice bran oil with few impurities and light color, so as to reduce the difficulty of subsequent refining of rice bran oil and the loss of neutral oil and nutrients. Summary of the Invention

[0007] To solve the above problems existing in the existing processing technology of crude rice bran oil, the first aspect of the present invention provides a processing method for rice bran, and the method includes: performing radio frequency heating treatment on frozen rice bran.

[0008] In one or more embodiments, the frozen rice bran is obtained by freezing the rice bran.

[0009] In one or more embodiments, the freezing temperature of the freezing step is -20 to 0 °C, and the freezing time of the freezing step is 2 - 10 h.

[0010] In one or more embodiments, the freezing temperature of the freezing step is -10 to -5 °C, and the freezing time of the freezing step is 2 - 6 h.

[0011] In one or more embodiments, in the radio frequency heating step, the plate spacing of the radio frequency heating device is 5 - 15 cm.

[0012] In one or more embodiments, in the radio frequency heating step, the radio frequency heating temperature is 80 - 120 °C.

[0013] In one or more embodiments, in the radio frequency heating step, the hot air temperature is 50 - 70 °C.

[0014] In one or more embodiments, in the radio frequency heating step, the radio frequency heating time is 1 to 15 minutes.

[0015] In one or more embodiments, the water content of the rice bran raw material in the freezing step is 15-25%.

[0016] In one or more embodiments, a rice bran conditioning step is further included before the freezing step.

[0017] In one or more embodiments, the conditioning liquid in the conditioning step is one or more of an aqueous sodium chloride solution, an aqueous potassium chloride solution, an aqueous calcium chloride solution, an aqueous magnesium chloride solution, and an aqueous zinc chloride solution.

[0018] The second aspect of the present invention provides a kind of rice bran, which is prepared by the method described in the first aspect of the present invention.

[0019] The third aspect of the present invention provides a method for preparing crude rice bran oil, the method comprising the step of extracting oil from the rice bran prepared by the method described in the first aspect of the present invention or the rice bran described in the second aspect of the present invention.

[0020] In one or more embodiments, the oil extraction is solvent extraction.

[0021] In one or more embodiments, the solvent is one or more of n-hexane, petroleum ether, and isopropanol.

[0022] The fourth aspect of the present invention provides a kind of crude rice bran oil, which is prepared by the method described in the third aspect of the present invention.

[0023] In one or more embodiments, the content of gum-soluble impurities in the crude rice bran oil is 0.2%-0.5%.

[0024] In one or more embodiments, the wax content in the crude rice bran oil is 1.0%-1.5%.

[0025] The fifth aspect of the present invention provides a method for preparing rice bran oil, the method comprising the step of refining the crude rice bran oil prepared by the method described in the third aspect of the present invention or the rice bran oil described in the fourth aspect of the present invention.

[0026] In one or more embodiments, the refining includes one or more of degumming, deacidification, decolorization, dewaxing, and deodorization.

[0027] The sixth aspect of the present invention provides a kind of rice bran oil, which is prepared by the method described in the fourth aspect of the present invention.

[0028] The seventh aspect of the present invention provides a blended oil, which includes the crude rice bran oil described in the fourth aspect of the present invention and / or the rice bran oil described in the sixth aspect of the present invention.

[0029] The eighth aspect of the present invention provides a method for preparing a blended oil, which includes mixing the crude rice bran oil of the fourth aspect of the present invention and / or the rice bran oil of the sixth aspect of the present invention with at least one base oil. Through the process of the present invention, the content of colloid-soluble impurities and rice bran wax in the crude rice bran oil can be significantly reduced, and the deepening of the color of the crude oil can be inhibited, which helps to improve the subsequent refining efficiency and reduce the loss of neutral oil and nutrients during the refining process. Detailed Embodiments

[0030] To enable those skilled in the art to understand the characteristics and effects of the present invention, the following provides a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meaning understood by those skilled in the art regarding the present invention. In case of conflict, the definition in this specification shall prevail.

[0031] The theories or mechanisms described and disclosed herein, whether correct or incorrect, shall not limit the scope of the present invention in any way, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.

[0032] In this article, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are only for the sake of brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions). In this article, unless otherwise specified, the percentage refers to the mass percentage, and the ratio refers to the mass ratio.

[0033] In this article, for the sake of concise description, all possible combinations of all technical features in each embodiment or example are not described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as the scope described in this specification.

[0034] In this article, unless otherwise specified, the raw materials mentioned can adopt the conventional raw materials in the art, and the processes mentioned can adopt the conventional operation methods in the art. Those skilled in the art can reasonably determine according to the content disclosed herein and the prior art.

[0035] Rice bran raw material before freezing treatment

[0036] The rice bran raw material used in the present invention is derived from rice and is obtained according to the currently known prior art. Rice bran is a mixture of the cortex (including the pericarp, testa, nucellar layer, and aleurone layer) milled off during the whitening process of brown rice, as well as a small amount of rice embryo and small broken rice particles.

[0037] The particle size of the rice bran is not particularly limited, and any existing particle size of rice bran can be used.

[0038] In some specific embodiments, the particle size of the rice bran is not higher than 750 microns.

[0039] In some specific embodiments, the moisture content of the rice bran is 8 - 14%.

[0040] Rice bran conditioning step

[0041] The rice bran conditioning step of the present invention refers to the step of contacting the rice bran with a conditioning liquid for a certain period of time to make the moisture content of the rice bran reach a certain range. The rice bran can be conditioned by spraying, dropping, or directly adding the conditioning liquid.

[0042] In some specific embodiments, the conditioning liquid is one or more of an aqueous sodium chloride solution, an aqueous potassium chloride solution, an aqueous calcium chloride solution, an aqueous magnesium chloride solution, and an aqueous zinc chloride solution.

[0043] In some specific embodiments, the conditioning liquid is an aqueous sodium chloride solution with a concentration of 0.1 - 2% by mass.

[0044] In some specific embodiments, based on the total weight of the rice bran, the addition amount of the conditioning liquid is 1 - 20%.

[0045] In some specific embodiments, after the conditioning step is completed, the moisture content of the rice bran reaches 15 - 25%.

[0046] Rice bran freezing step

[0047] The freezing step of the present invention refers to subjecting the rice bran to a freezing treatment in an environment of - 20 to 0 °C. The freezing environment of the rice bran can be arbitrary. For example, the rice bran is placed in a container with a certain thickness for freezing treatment.

[0048] In some specific embodiments, in the freezing step, the rice bran is placed in a container with a thickness of 3 - 7 cm.

[0049] In some specific embodiments, the freezing temperature is - 10 to 0 °C.

[0050] In some specific embodiments, the freezing time is 2 - 10 h.

[0051] Rice bran radio frequency heating step

[0052] The rice bran radio frequency heating step of the present invention is to place the rice bran between the two plates of a radio frequency device to heat the rice bran. The radio frequency device of the present invention can be any commercially available radio frequency device. For example, it can be a radio frequency heating device with a wavelength of 11 m, a frequency of 27.12 MHz, and a power of 6 KW.

[0053] In some specific embodiments, the distance between the plates is 5 - 15 cm.

[0054] In some specific embodiments, the radio frequency temperature is 80°C - 120°C.

[0055] In some specific embodiments, the hot air temperature in the radio frequency device is 50 - 70°C.

[0056] In some specific embodiments, the radio frequency treatment time is 1 - 15 min;

[0057] The present invention provides a method for preparing crude rice bran oil, and the method includes a step of extracting oil from the rice bran prepared by the method of the present invention.

[0058] The oil extraction step of the present invention can be any conventional oil extraction method. For example, it can be solvent extraction, pressing method, aqueous enzymatic method, etc. The method of solvent extraction can be selected for oil extraction, with an extraction temperature of 30 - 60°C and an extraction time of 4 - 24 h. The extraction solvent can be any commonly used extraction solvent in the art, including one or more of n - hexane, petroleum ether, and isopropanol.

[0059] In some specific embodiments, the extraction solvent contains n - hexane and isopropanol.

[0060] In some specific embodiments, the ratio of n - hexane to isopropanol in the extraction solvent is 60:40 - 90:10 (volume ratio).

[0061] The present invention provides a crude rice bran oil, which is obtained by extracting oil from the rice bran prepared by the method of the present invention.

[0062] In some specific embodiments, the content of colloidal impurities in the crude rice bran oil is 0.2% - 0.5%, and / or the wax content is 1.0% - 1.5%.

[0063] In some specific embodiments, the colloidal impurities include one or more of phospholipids, proteins, saccharides, resins, and mucus substances.

[0064] The present invention provides a method for preparing rice bran oil, characterized in that the method includes a step of refining the crude rice bran oil obtained by the method of the present invention or the crude rice bran oil of the present invention.

[0065] Crude oil refining

[0066] In some embodiments, the present invention provides a method for refining crude rice bran oil, comprising one or more of the steps of degumming, deacidification, decolorization, dewaxing, and deodorization. The process conditions for degumming, deacidification, decolorization, dewaxing, degreasing, and deodorization can be conventional process conditions in the art and can be adjusted according to the actual production situation.

[0067] In the present invention, the degumming method can be a conventional degumming method in the art, and the specific process is well-known to those skilled in the art. For example, it can but is not limited to adopt the methods in "Bailey's Industrial Oil and Fat Products" (Volume VI), etc. Generally, degumming includes: after filtering the crude oil to remove solid impurities, adding a degumming medium to degum the crude oil. The degumming medium can be a conventional degumming medium in the art, such as citric acid solution, phosphoric acid solution, and degumming enzyme. The temperature of the reaction system can be in the range of 40 - 90 °C, depending on different degumming media.

[0068] After degumming, deacidification can be carried out. Its main purpose is to remove free fatty acids in the crude oil, and at the same time remove some impurities such as pigments, phospholipids, hydrocarbons, and mucilage. Physical deacidification methods can be used for deacidification. For example, the degummed oil can be treated at a pressure of 0.02 - 0.6 kPa and a temperature of 180 - 250 °C to obtain deacidified oil. Alternatively, the alkali refining method can be used for deacidification. In the present invention, the alkali refining method can be a conventional alkali refining method in the art, and the specific process is well-known to those skilled in the art. For example, it can but is not limited to adopt the methods in "Bailey's Industrial Oil and Fat Products" (Volume VI), etc. Generally, alkali refining includes: adding an alkali solution to the oil, reacting at a certain temperature for a period of time, then adding hot water to wash away the soap, and drying.

[0069] The decolorization step can use a decolorizing adsorbent. The adsorbent can be selected from activated carbon, natural organic adsorbents, natural inorganic adsorbents, and synthetic adsorbents. The dosage of the adsorbent, based on the total weight of the system to be treated, can be 0.1% - 2%, preferably 0.15 - 0.5%. The decolorization temperature can be above 60 °C, preferably 70 °C - 90 °C.

[0070] The dewaxing step can be achieved by means of cooling crystallization and crystal cultivation. Pump the oil to be dewaxed into a crystal cultivation tank, control the temperature to 50 - 60 °C, let it stand for 10 - 60 min, and then start cooling crystallization. It can be reduced to 2 - 6 °C within 10 - 60 hours, and then cultivate crystals at this temperature for 6 - 10 hours. After crystal cultivation, filter.

[0071] The deodorization treatment is mainly used to remove possible off-flavors such as burnt smell, solvent smell, and soap smell in the oil. There is no particular limitation on the deodorization device, and conventional devices in the art can be used, such as deodorization towers. There is no particular limitation on the deodorization temperature, time, and vacuum degree, and conventional temperature, time, and vacuum degree in the art can be selected. Preferably, the deodorization temperature is controlled between 170°C and 220°C, the deodorization time is controlled between 40 - 90 minutes, and the vacuum degree of the deodorization tower is controlled between 0.5 - 3 mbar (the absolute vacuum degree is recorded as 0 mbar).

[0072] In addition, for the needs of improving flavor, taste, and durability, etc., the rice bran oil described in the present invention can also be added with various additives and nutritional components. In some specific embodiments, the additive can be an antioxidant, and the edible antioxidants that can be listed can be selected from one or more of tert-butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA), dibutylhydroxytoluene (BHT), vitamin E, rosemary extract, and tea extract. For the nutritional components, it can include various fat-soluble vitamin components required by the human body, etc.

[0073] For the blended oil provided by the present invention, in addition to the above-mentioned rice bran oil of the present invention, other types of oils can be added in any proportion according to actual nutritional needs or taste needs.

[0074] For the types of these other types of oils, they can be various edible vegetable oils and animal oils.

[0075] Typically, the other vegetable oils that can be used are selected from: sunflower oil, palm oil, palm kernel oil, peanut oil, rapeseed oil, soybean oil, linseed oil, cottonseed oil, safflower oil, perilla oil, tea seed oil, hemp seed oil, jojoba oil, olive oil, cocoa butter, Chinese tallow tree seed oil, almond oil, tung tree seed oil, rubber seed oil, corn germ oil, wheat germ oil, sesame seed oil, evening primrose oil, hazelnut oil, pumpkin seed oil, walnut oil, grape seed oil, sesame oil, borage oil, seabuckthorn oil, tomato seed oil, macadamia nut oil, coconut oil, etc.

[0076] Typically, the other animal oils that can be used are selected from: beef tallow, lard, duck oil, mutton fat, chicken oil, fish oil, seal oil, whale oil, shrimp oil, dolphin oil, lanolin, etc.

[0077] The present invention also provides a food, which includes the rice bran oil, rice bran crude oil, or blended oil described in the present invention.

[0078] In addition, the above-mentioned foods can be various ready-to-eat foods, semi-finished products, or food flavor enhancers, etc. Typically, various fried foods, pastries, semi-cooked flour products, various pickled products, etc. can be listed. There is no limitation on the treatment method in the treatment of foods with the rice bran oil, crude rice bran oil or blended oil of the present invention, and it can be used for frying, coloring, flavoring or fragrance enhancing of foods.

[0079] The advantages of the present invention are as follows: The existing crude rice bran oil has the disadvantages of high viscosity, dark color, and high impurity content, which increases the difficulty of subsequent refining processes such as degumming, decoloring, and dewaxing; by using the method of the present invention, high-quality crude rice bran oil with less gum and wax content and light color can be obtained, thereby reducing the difficulty of subsequent refining of crude rice bran oil and the loss of neutral oil and nutrients.

[0080] The following examples are further elaborations of the present invention, but the content of the present invention is not limited by the following content. The embodiments in the specification of the present invention are only used to illustrate the present invention, and they do not limit the protection scope of the present invention. The protection scope of the present invention is only defined by the claims, and any omission, substitution or modification made by those skilled in the art based on the disclosed embodiments of the present invention will fall within the protection scope of the present invention.

[0081] Conventional instrument equipment in the art is used in the following examples. For the experimental methods without specific conditions indicated in the following examples, they are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. Various raw materials are used in the following examples, and unless otherwise stated, they are all conventional commercially available products. In the specification of the present invention and the following examples, unless otherwise specified, "%" represents weight percentage and "parts" represents weight parts.

[0082] The moisture determination refers to GB / T5009.3–2010;

[0083] The color determination refers to GB / T22460–2008;

[0084] The determination method of the content of gum-soluble impurities refers to Chapter 8 "Determination of the Content of Oil Deposits" in "Inspection and Analysis of Oilseeds and Oils";

[0085] The determination of wax content refers to GB / T15688-2008;

[0086] Radio frequency heating equipment: Model SO6B, wavelength 11m, frequency 27.12MHz, power 6KW, manufactured by Strayfield Internation, UK.

[0087] Example 1

[0088] Weigh 100 g of fresh rice bran (with a moisture content of 10%) and spray it with an aqueous NaCl solution with a concentration of 0.1% by mass to adjust the moisture content of the rice bran to 15%; then spread the rice bran evenly in a container with a thickness of 7 cm and place it in an environment at 0 °C for freezing for 8 h; then immediately place it between the two electrodes of a radio frequency heating device, adjust the electrode spacing to 5 cm, set the radio frequency temperature to 120 °C, the hot air temperature to 50 °C, and maintain for 1 min; finally, add the rice bran to a n - hexane - isopropanol composite solvent with a volume ratio of 60:40 at a solid - liquid ratio of 1:3 for extraction, with an extraction temperature of 30 °C and an extraction time of 24 h; then filter to separate the solvent phase, and remove the solvent by rotary evaporation at 50 °C to obtain crude rice bran oil.

[0089] Comparative Example 1

[0090] Weigh 100 g of fresh rice bran (with a moisture content of 10%) and spread it evenly in a container with a thickness of 7 cm, place it between the two electrodes of a radio frequency heating device, adjust the electrode spacing to 5 cm, set the radio frequency temperature to 120 °C, the hot air temperature to 50 °C, and maintain for 1 min; finally, add the rice bran to a n - hexane - isopropanol composite solvent with a volume ratio of 60:40 at a solid - liquid ratio of 1:3 for extraction, with an extraction temperature of 30 °C and an extraction time of 24 h; then filter to separate the solvent phase, and remove the solvent by rotary evaporation at 50 °C to obtain crude rice bran oil.

[0091] Comparative Example 2

[0092] Weigh 100 g of fresh rice bran (with a moisture content of 10%) and spread it evenly in a PP container with small holes densely distributed at the bottom and around with a thickness of 7 cm, place it in an environment at 0 °C for low - temperature freezing for 8 h, and finally add the rice bran to a n - hexane - isopropanol composite solvent with a volume ratio of 60:40 at a solid - liquid ratio of 1:3 for extraction, with an extraction temperature of 30 °C and an extraction time of 24 h; then filter to separate the solvent phase, and remove the solvent by rotary evaporation at 50 °C to obtain crude rice bran oil.

[0093] Comparative Example 3

[0094] Weigh 100 g of fresh rice bran (with a moisture content of 10%) and spread it evenly in a container with a thickness of 7 cm, place it between the two electrodes of a radio frequency heating device, adjust the electrode spacing to 5 cm, set the radio frequency temperature to 120 °C, the hot air temperature to 50 °C, and maintain for 1 min; spray it with an aqueous NaCl solution with a concentration of 0.1% by mass to adjust the moisture content of the rice bran to 15%, and place it in an environment at 0 °C for freezing for 8 h; finally, add the rice bran to a n - hexane - isopropanol composite solvent with a volume ratio of 60:40 at a solid - liquid ratio of 1:3 for extraction, with an extraction temperature of 30 °C and an extraction time of 24 h; then filter to separate the solvent phase, and remove the solvent by rotary evaporation at 50 °C to obtain crude rice bran oil.

[0095] Comparative Example 4

[0096] Weigh 100 g of fresh rice bran (with a moisture content of 10%), spray it with an aqueous NaCl solution with a concentration of 0.1% by mass, adjust the moisture content of the rice bran to 15%, and perform extrusion puffing stabilization (extrusion conditions: 120 °C, 3 min). Finally, add the rice bran to a n-hexane-isopropanol composite solvent with a volume ratio of 60:40 at a solid-liquid ratio of 1:3 for extraction. The extraction temperature is 30 °C and the extraction time is 24 h. Then, filter to separate the solvent phase, and remove the solvent by rotary evaporation at 50 °C to obtain crude rice bran oil.

[0097] Comparative Example 5

[0098] Weigh 100 g of fresh rice bran (with a moisture content of 10%), add it to a n-hexane-isopropanol composite solvent with a volume ratio of 60:40 at a solid-liquid ratio of 1:3 for extraction. The extraction temperature is 30 °C and the extraction time is 24 h. Then, filter to separate the solvent phase, and remove the solvent by rotary evaporation at 50 °C to obtain crude rice bran oil.

[0099] Table 1 Comparison of related indexes of crude oil

[0100]

[0101]

[0102] By comparing the crude rice bran oil extracted by the present invention with that produced by other methods, it can be seen that the crude rice bran oil of the present invention has lower colloidal impurities and wax content than that produced by other methods, and also has certain advantages in color compared with most processes.

[0103] Example 2

[0104] Weigh 100 g of fresh rice bran (with a moisture content of 14%), spray it with an NaCl solution with a concentration of 2%, and adjust the moisture content of the rice bran to 25%. Then, spread the rice bran evenly in a container with a thickness of 3 cm, place it in an environment of -10 °C for low-temperature freezing for 2 h. Then, immediately place it between the two electrodes of a radio frequency heating device, adjust the electrode spacing to 15 cm, set the radio frequency temperature to 80 °C, the hot air temperature to 70 °C, and maintain for 15 min. Finally, add the rice bran to a n-hexane-isopropanol composite solvent with a volume ratio of 90 / 10 at a solid-liquid ratio of 1∶10 for extraction. The extraction temperature is 60 °C and the extraction time is 4 h. Then, filter to separate the solvent phase, and remove the solvent by rotary evaporation at 50 °C to obtain crude rice bran oil.

[0105] Example 3

[0106] Weigh 100 g of fresh rice bran (with a moisture content of 12%) and spray it with a 1% NaCl solution to adjust the moisture content of the rice bran to 20%; then spread the rice bran evenly in a container with a thickness of 4 cm, place it in an environment at -8 °C for cryogenic freezing for 4 h; then immediately place it between the two electrodes of a radio frequency heating device, adjust the electrode spacing to 10 cm, set the radio frequency temperature to 100 °C, the hot air temperature to 60 °C, and maintain for 8 min; finally, add the rice bran to a n - hexane - isopropanol composite solvent with a volume ratio of 80 / 20 according to a solid - liquid ratio of 1∶6 for extraction, with an extraction temperature of 50 °C and an extraction time of 8 h; then filter by suction to separate the solvent phase, and remove the solvent by rotary evaporation at 50 °C to obtain crude rice bran oil.

[0107] Example 4

[0108] Weigh 100 g of fresh rice bran (with a moisture content of 11.5%) and spray it with a 0.5% NaCl solution to adjust the moisture content of the rice bran to 18%; then spread the rice bran evenly in a container with a thickness of 5 cm, place it in an environment at -6 °C for cryogenic freezing for 6 h; then immediately place it between the two electrodes of a radio frequency heating device, adjust the electrode spacing to 7.5 cm, set the radio frequency temperature to 110 °C, the hot air temperature to 65 °C, and maintain for 6 min; finally, add the rice bran to a n - hexane - isopropanol composite solvent with a volume ratio of 70 / 30 according to a solid - liquid ratio of 1:8 for extraction, with an extraction temperature of 40 °C and an extraction time of 12 h; then filter by suction to separate the solvent phase, and remove the solvent by rotary evaporation at 50 °C to obtain crude rice bran oil.

[0109] Example 5

[0110] Weigh 100 g of fresh rice bran (with a moisture content of 8%) and spray it with a 1.5% NaCl solution to adjust the moisture content of the rice bran to 22%; then spread the rice bran evenly in a container with a thickness of 6 cm, place it in an environment at -4 °C for cryogenic freezing for 7 h; then immediately place it between the two electrodes of a radio frequency heating device, adjust the electrode spacing to 8.5 cm, set the radio frequency temperature to 115 °C, the hot air temperature to 55 °C, and maintain for 10 min; finally, add the rice bran to a n - hexane - isopropanol composite solvent with a volume ratio of 85 / 15 according to a solid - liquid ratio of 1:5 for extraction, with an extraction temperature of 50 °C and an extraction time of 10 h; then filter by suction to separate the solvent phase, and remove the solvent by rotary evaporation at 50 °C to obtain crude rice bran oil.

[0111] Example 6

[0112] Weigh 100 g of fresh rice bran (with a moisture content of 14%) and spray it with a 2% NaCl solution to adjust the moisture content of the rice bran to 25%; then spread the rice bran evenly in a container with a thickness of 3 cm and place it in an environment at 0 °C for cryogenic freezing for 10 h; then immediately place it between the two electrodes of a radio frequency heating device, adjust the electrode spacing to 15 cm, set the radio frequency temperature to 80 °C, the hot air temperature to 70 °C, and maintain for 15 min; finally, add the rice bran to a petroleum ether-isopropanol composite solvent with a volume ratio of 90 / 10 at a solid-liquid ratio of 1:10 for extraction, with an extraction temperature of 60 °C and an extraction time of 4 h; then filter to separate the solvent phase and remove the solvent by rotary evaporation at 50 °C to obtain crude rice bran oil.

[0113] Example 7

[0114] Weigh 100 g of fresh rice bran (with a moisture content of 12%) and spray it with a 1% CaCl2 solution to adjust the moisture content of the rice bran to 20%; then spread the rice bran evenly in a container with a thickness of 4 cm and place it in an environment at -5 °C for cryogenic freezing for 5 h; then immediately place it between the two electrodes of a radio frequency heating device, adjust the electrode spacing to 10 cm, set the radio frequency temperature to 100 °C, the hot air temperature to 60 °C, and maintain for 8 min; finally, add the rice bran to petroleum ether solvent at a solid-liquid ratio of 1:6 for extraction, with an extraction temperature of 50 °C and an extraction time of 8 h; then filter to separate the solvent phase and remove the solvent by rotary evaporation at 50 °C to obtain crude rice bran oil.

[0115] Example 8

[0116] Weigh 100 g of fresh rice bran (with a moisture content of 11.5%) and spray it with a 0.5% KCl solution to adjust the moisture content of the rice bran to 18%; then spread the rice bran evenly in a container with a thickness of 5 cm and place it in an environment at -10 °C for cryogenic freezing for 3 h; then immediately place it between the two electrodes of a radio frequency heating device, adjust the electrode spacing to 7.5 cm, set the radio frequency temperature to 110 °C, the hot air temperature to 65 °C, and maintain for 6 min; finally, add the rice bran to n-hexane solvent at a solid-liquid ratio of 1:8 for extraction, with an extraction temperature of 40 °C and an extraction time of 12 h; then filter to separate the solvent phase and remove the solvent by rotary evaporation at 50 °C to obtain crude rice bran oil.

[0117] Example 9

[0118] Weigh 100 g of fresh rice bran (with a moisture content of 8%) and spray it with a 1.5% MgCl2 solution to adjust the moisture content of the rice bran to 22%; then spread the rice bran evenly in a container with a thickness of 6 cm and place it in an environment of -20 °C for cryogenic freezing for 2 h; then immediately place it between the two electrodes of a radio frequency heating device, adjust the electrode distance to 8.5 cm, set the radio frequency temperature to 115 °C, the hot air temperature to 55 °C, and maintain for 10 min; finally, add isopropanol solvent to the rice bran according to a solid-liquid ratio of 1:5 for extraction, the extraction temperature is 50 °C, and the extraction time is 10 h; then filter to separate the solvent phase, and remove the solvent by rotary evaporation at 50 °C to obtain crude rice bran oil.

[0119] Table 2 Comparison of related indexes of crude rice bran oil

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[0121]

Claims

1. A processing method of rice bran, characterized in that, The method includes: performing radio frequency heating treatment on frozen rice bran; wherein, Before the frozen rice bran, there is also a step of conditioning rice bran, and the conditioning liquid in the rice bran conditioning step is one or more of an aqueous sodium chloride solution, an aqueous potassium chloride solution, an aqueous calcium chloride solution, an aqueous magnesium chloride solution, and an aqueous zinc chloride solution; The concentration of the conditioning liquid is 0.1 - 2% by mass; After the rice bran conditioning step is completed, the water content of the rice bran reaches 15 - 25%; In the radio frequency heating, the plate spacing of the radio frequency heating device is 5 - 15 cm, the radio frequency heating temperature is 80 - 120 °C, and the radio frequency heating time is 1 - 15 min.

2. The method according to claim 1, characterized in that, The freezing temperature of the frozen rice bran is -20 to 0 °C, and the freezing time is 2 - 10 h.

3. The method according to claim 2, characterized in that The freezing temperature of the frozen rice bran is -10 to -5 °C, and the freezing time is 2 - 6 h.

4. The method according to any one of claims 1 to 3, characterized in that, In the radio frequency heating, the hot air temperature is 50 - 70 °C.

5. Rice bran prepared by the method according to any one of claims 1 - 4.

6. A preparation method of crude rice bran oil, characterized in that, The method includes a step of extracting oil from the rice bran according to claim 5.

7. A crude rice bran oil, characterized in that, The crude rice bran oil is prepared by the method according to claim 6.

8. The crude rice bran oil according to claim 7, characterized in that, The content of gum-soluble impurities in the crude rice bran oil is 0.2% - 0.5%, and / or the wax content is 1.0% - 1.5%.

9. A method for preparing rice bran oil, characterized in that, The method includes a step of refining the crude rice bran oil according to claim 7.

10. The method according to claim 9, wherein The refining includes one or more of degumming, deacidification, decolorization, dewaxing, and deodorization.

11. A rice bran oil, characterized in that, The rice bran oil is prepared by the method according to claim 9 or 10.

12. A blended oil, characterized in that, The blended oil includes the crude rice bran oil according to claim 7 and / or the rice bran oil according to claim 11.

13. A method for preparing a blended oil, including mixing the crude rice bran oil according to claim 7 and / or the rice bran oil according to claim 11 with at least one base oil.

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