Rice bran oil and preparation method thereof

Abstract

The invention belongs to the technical field of oil processing, and particularly relates to rice bran oil and a preparation method thereof. According to the method, high-temperature and high-humidity gas jet impact is adopted for stabilizing rice bran; adding water, uniformly mixing, and grinding for 120-150 minutes by adopting an ultrasonic combined high-energy medium mill, so as to obtain rice bran emulsion; and mixing the rice bran emulsion with a salt solution, adding acid to adjust the pH value to 4.5, stirring, and centrifuging to obtain the rice bran oil. The invention provides the preparation method of the rice bran oil with high yield and high quality. According to the method, enzyme deactivation treatment is performed through a high-temperature and high-humidity gas jet impact technology, cell walls of rice bran are destroyed in combination with a high-energy medium mill and ultrasonic waves, dissolution of grease is promoted, the stability of emulsion is destroyed in combination with salt-pH, rice bran protein is precipitated, oil drops are gathered again, and therefore rice bran oil is separated out. The problems that rice bran is prone to rancidification, oil production is difficult, and oil quality is low are solved.

Description

Technical Field

[0001] The present application belongs to the technical field of oil processing, and specifically relates to rice bran oil and a preparation method thereof. Background Art

[0003] The lipase and peroxidase activities in rice bran are high and are easily spoiled. Fresh rice bran must be stabilized before it can be used in food. The main heat treatment methods for rice bran stabilization include extrusion puffing, radiation method, steam treatment, etc. Extrusion puffing can easily lead to the degradation of heat-sensitive components such as vitamin E in rice bran and the denaturation of rice bran protein; the radiation method usually uses infrared or microwave, which will result in uneven heating; and the direct steam heating method will increase the moisture in rice bran, and it is difficult for steam to penetrate the material layer and distribute evenly. Therefore, in actual production, methods such as extending the heating time and increasing the heat exchange area of ​​the equipment are often used to overcome the above problems, but this will increase the cost of rice bran oil production. In addition, the current methods for extracting rice bran oil from rice bran mainly include mechanical pressing and solvent leaching. Due to the poor physical properties of rice bran such as hardness and brittleness, the traditional mechanical pressing method consumes a lot of energy and has a low oil yield, and the residual oil rate of rice bran residue exceeds 5.0%. The extraction method often uses organic solvents or water-enzyme method. The organic solvent method has problems such as chemical pollution; the water-enzyme method has difficulty in demulsification, that is, the oil and protein are tightly combined and difficult to extract, resulting in a low yield. Therefore, the development of a simple, efficient, green, safe, and industrializable method for preparing high-quality rice bran oil is of great significance for expanding the rice bran oil market and breaking through the bottleneck of rice bran oil development. Summary of the invention

[0004] The object of the present invention is to solve the deficiencies in the prior art and to provide a method for preparing high-quality rice bran oil, which specifically adopts the following technical scheme: One aspect of the present invention provides a method for preparing rice bran oil, comprising the following steps: The rice bran is stabilized by high temperature and high humidity gas jet impact; The stabilized rice bran is mixed with water and then treated with ultrasound combined with high-energy medium mill for 120 min to 150 min to obtain a rice bran emulsion; The rice bran emulsion and the salt solution are mixed, and then acid is added to adjust the pH to 4.5, stirred, and centrifuged to obtain the rice bran oil.

[0005] The method of the present invention first utilizes high-temperature and high-humidity gas jet impact to inactivate lipase and peroxidase in fresh rice bran, then mixes it with water and places it in an ultrasonic and high-energy medium mill for grinding, and dissolves the oil by continuously crushing and refining the rice bran, then adds a saturated sodium chloride solution and adjusts the pH to 4.5 for demulsification treatment, so that protein precipitation and oil droplets re-aggregate, and high-quality rice bran oil can be obtained after centrifugation. The method solves the problems that rice bran is easy to become rancid, the oil yield is difficult, and active ingredients such as oryzanol are easy to degrade. In addition, the method is simple to operate, green and safe, has high processing efficiency, and is easy to realize continuous production.

[0006] The present invention is based on high-temperature and high-humidity gas jet impact technology and efficient enzyme inactivation treatment. Fresh rice bran is used as raw material, and a method of destroying the cell wall of rice bran by ultrasonic combined with high-energy medium mill is adopted. Rice bran oil is extracted with water, and then a saturated sodium chloride solution is combined with an acid adjustment method to destroy the stability of the emulsion, so that the oil is released and the oil droplets are aggregated, and finally a rice bran oil with excellent quality is obtained. The experimental data results according to the embodiment of the present invention show that compared with the rice bran oil not subjected to enzyme inactivation treatment by high-temperature and high-humidity gas jet impact technology or treated by traditional enzyme inactivation technology, the acid value of the rice bran oil prepared by the process is low; compared with the rice bran oil directly subjected to high-energy medium mill treatment or directly centrifuged without demulsification, the oil yield of the process is higher. In addition, the rice bran oil prepared by the present invention has an acid value of ≤4mgKOH / g, a clear color, a large amount of beneficial components such as oryzanol are retained, and the method has the advantages of simple operation, mild reaction conditions, no chemical pollution, high oil yield, and stable oil quality. In summary, the present invention adopts multiple technical means to solve the problems of easy rancidity of rice bran, low oil yield and serious loss of active ingredients, realizes the high-value transformation of rice bran, and effectively broadens the development scope and ideas of rice bran oil products, and is very easy to realize industrial production.

[0007] It should be noted that the ultrasonic combined high energy medium grinding treatment equipment is an integrated equipment, and its grinding chamber structure diagram is as follows Figure 1 As shown, the treatment process of ultrasound combined with high-energy medium mill is as follows: ultrasonic probes (2 and 3) are attached outside the grinding chamber to ultrasonicate the liquid in the chamber, and the circulation system of ultrasound combined with high-energy medium mill allows the rice bran suspension in the stirring cylinder to enter the grinding chamber of the high-energy medium mill through the inlet pipe area 1, and then leave the grinding chamber through the discharge port 4. The rice bran suspension is continuously circulated into the grinding chamber where grinding and ultrasound are turned on at the same time, and the combined action of the two causes the destruction of the rice bran cell wall. Compared with using high-energy medium mill and ultrasound to treat rice bran solution separately, combining the two processes can shorten the working time and reduce costs on the one hand, and on the other hand, the rice bran is violently moved and broken in the grinding chamber. In this state, the energy provided by ultrasound is more likely to act on the key sites of oil and fat, thereby more efficiently destroying the rice bran cell wall and releasing oil and fat, that is, the synergistic effect of high-energy medium mill and ultrasound is better than the individual effects of the two.

[0008] As a further preferred embodiment, the parameters of the high temperature and high humidity gas jet impact treatment are: relative humidity 25%-30%, wind speed 10±0.5 m / s, temperature 100-120°C, time 2-3 min. In the preparation process, if the treatment time is too short, the enzyme inactivation effect is poor, resulting in the rice bran oil being decomposed into free fatty acids by lipase, resulting in too high acid value; if the treatment time is too long, not only energy consumption will be lost and cost will be increased, but also the heat-sensitive components in the rice bran may be lost.

[0009] As a further preferred embodiment, the specific process parameters of the ultrasonic combined high-energy medium mill are as follows: the rotation speed is 1200 r / min, the diameter of the grinding beads is 0.6 mm, the filling degree of the grinding chamber is 70%-80%, and the power of the ultrasonic treatment is 300 W. In the preparation process, the higher the filling degree of the grinding chamber, the better the grinding effect, but when the filling degree is ≥80%, the excessive filling rate will affect the fluidity of the material in the cavity, and increase the friction between the medium and the medium and the material, thereby reducing the grinding efficiency and affecting the dissolution of rice bran oil. Therefore, the grinding chamber filling degree is 70%-80%, which is better.

[0010] As a further preferred embodiment, the temperature during grinding in the high energy medium mill is less than 30° C. During the preparation process, keeping the temperature below 30° C. can reduce the loss of heat-sensitive components such as oryzanol, squalene, and vitamin E in rice bran oil.

[0011] As a further preferred embodiment, the ratio of rice bran to water is 1:8-12. In the preparation process, water is used as an extractant, and too high or too low a proportion of water will affect the dissolution of rice bran oil.

[0012] As a further preferred embodiment, the salt solution is a sodium chloride solution, and the volume ratio of the sodium chloride solution to the rice bran emulsion is 1:1-2. In the preparation process, sodium chloride is an electrolyte. When its concentration is low, the charge it carries plays a stabilizing role relative to the surfactant; when its concentration continues to increase, the charge it carries produces a greater repulsive force relative to the charge carried by the surfactant, destroying its stability; and saturated sodium chloride solution has the best demulsification effect.

[0013] As a further preferred embodiment, the acid is a citric acid solution or a hydrochloric acid solution. In the preparation process, the solution pH is adjusted to 4.5 by using an acid, and then stirred at room temperature for 30-40 minutes, and then centrifuged at 4800r / min for 30 minutes. Among them, the protein is easier to precipitate at the isoelectric point of rice bran protein, which is conducive to destroying the stability of the emulsion, thereby increasing the yield of rice bran oil.

[0014] As a further preferred embodiment, the stirring time is 30 min-40 min; the centrifugal speed is 4800 r / min, and the time is 30 min.

[0015] Another aspect of the present invention provides a rice bran oil prepared by the above preparation method, wherein the acid value of the rice bran oil is ≤4 mgKOH / g. The yield of the rice bran oil prepared by the method of the present invention is ≥80%, the acid value is ≤4 mg KOH / g, and the active ingredients such as oryzanol are well preserved, which greatly expands its application scenarios.

[0016] The beneficial effects of the present invention are: The present invention provides a method for preparing high-yield and high-quality rice bran oil. The method uses high-temperature and high-humidity gas jet impact technology to inactivate enzymes, combines high-energy medium milling with ultrasound to destroy the cell wall of rice bran, promotes the dissolution of oil, and then combines salt-pH to destroy the stability of the emulsion, so that rice bran protein is precipitated and oil droplets are re-aggregated, thereby separating rice bran oil, solving the problems of easy rancidity of rice bran, difficulty in oil production, and low oil quality. Among them, the high-temperature and high-humidity gas jet impact technology used in this method uses high-temperature and high-humidity gas as a heat transfer medium, which is sprayed onto the surface of the material after being heated by a centrifuge, and can achieve rapid heating of the material and uniform enzyme inactivation. This technology can inactivate lipase and peroxidase in the rice bran by uniformly heating the rice bran in a short time, reducing the loss of nutrients (oryzanol, vitamin E, etc.) and the generation of harmful substances such as benzopyrene. Secondly, the wet physical wall-breaking equipment adopted by the method, namely, ultrasonic combined high-energy medium mill, has the characteristics of low-temperature grinding, large processing capacity, good wall-breaking effect, and transmits energy to the stirring grinding medium and rice bran through the rotating shaft, and the violent movement between the grinding media produces shearing, extrusion and friction, and is assisted by ultrasound to make the rice bran between the media more easily deformed and broken, and promotes the destruction of the rice bran cell wall and the continuous dissolution of rice bran oil. Secondly, its perfect temperature control system can ensure that the material temperature is below 30°C during the grinding process, and the heat-sensitive active ingredients in the rice bran oil can be well retained, thereby realizing the preparation of high-yield and high-quality rice bran oil. In addition, the method proposed by the present invention is simple to operate, safe and controllable, has high processing efficiency, meets industrial production standards, and can be continuously produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 Shown is a schematic diagram of simultaneous treatment by ultrasound combined with high-energy media grinding. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0020] Example 1 A preparation method of rice bran oil specifically comprises the following steps: (1) Pretreatment: Sieve fresh rice bran through a 20-mesh sieve to remove broken particles and impurities.

[0021] (2) Stabilization: The rice bran in step (1) is placed in a high-temperature and high-humidity gas jet impact for stabilization treatment, with the parameters set as time 3 min, relative humidity 25%, wind speed 10±0.5 m / s, and temperature 110°C.

[0022] (3) Ultrasonic combined with high energy medium grinding (such as Figure 1 As shown in the figure): 1.2 kg of rice bran and 10.8 kg of distilled water in step (2) were mixed and placed in a stirring cylinder of an ultrasonic combined high-energy medium mill for grinding for 2 h. The grinding process was accompanied by ultrasonic treatment, and the temperature of the entire system was kept below 30 °C. The parameters were set as follows: the rotation speed was 1200 r / min, the diameter of the grinding beads (zirconia) was 0.6 mm, the filling degree of the grinding chamber was 75%, and the power of the ultrasonic treatment was 300 W.

[0023] (4) Demulsification: Add the rice bran emulsion in step (2) to a saturated sodium chloride solution at a volume ratio of 1:1.5, then adjust the pH of the emulsion to 4.5 with hydrochloric acid, stir for 30 min, and centrifuge at 4800 r / min for 30 min. The upper oil layer is the rice bran oil. The yield of the prepared rice bran oil is 82.16%, and the acid value is 3.56 mg KOH / g.

[0024] Example 2 (1) Pretreatment: Sieve fresh rice bran through a 20-mesh sieve to remove broken particles and impurities.

[0025] (2) Stabilization: The rice bran in step (1) is placed in a high-temperature and high-humidity gas jet impact for stabilization treatment, with the parameters set as time 3 min, relative humidity 25%, wind speed 10±0.5 m / s, and temperature 110°C.

[0026] (3) Ultrasonic combined high-energy medium mill grinding: 1.2 kg of rice bran and 10.8 kg of distilled water in step (2) were mixed and placed in the stirring cylinder of an ultrasonic combined high-energy medium mill for grinding for 2.5 h. The grinding process was accompanied by ultrasonic treatment, and the temperature of the entire system was kept below 30 °C. The parameters were set as follows: speed of 1200 r / min, diameter of grinding beads (zirconia) of 0.6 mm, filling degree of grinding chamber of 75%, and power of ultrasonic treatment of 300 W.

[0027] (4) Demulsification: Add the rice bran emulsion in step (2) to a saturated sodium chloride solution at a volume ratio of 1:1.5, then adjust the pH of the emulsion to 4.5 with hydrochloric acid, stir for 30 min, and centrifuge for 30 min at 4800 r / min. The upper oil layer is the rice bran oil. The yield of the prepared rice bran oil is 82.97%, and the acid value is 3.67 mg KOH / g.

[0028] Example 3 (1) Pretreatment: Sieve fresh rice bran through a 20-mesh sieve to remove broken particles and impurities.

[0029] (2) Stabilization: The rice bran in step (1) is placed in a high-temperature and high-humidity gas jet impact for stabilization treatment, with the parameters set as time 3 min, relative humidity 25%, wind speed 10±0.5 m / s, and temperature 110°C.

[0030] (3) Ultrasonic combined high-energy medium mill grinding: 1.2 kg of rice bran and 10.8 kg of distilled water in step (2) were mixed and placed in the stirring cylinder of an ultrasonic combined high-energy medium mill for grinding for 2.5 h. The grinding process was accompanied by ultrasonic treatment, and the temperature of the entire system was kept below 30 °C. The parameters were set as follows: speed of 1200 r / min, diameter of grinding beads (zirconia) of 0.6 mm, filling degree of grinding chamber of 75%, and power of ultrasonic treatment of 300 W.

[0031] (4) Demulsification: Add the rice bran emulsion in step (2) to a saturated sodium chloride solution in a volume ratio of 1:2, then adjust the pH of the emulsion to 4.5 with hydrochloric acid, stir for 30 min, and centrifuge for 30 min at 4800 r / min. The upper oil layer is the rice bran oil. The yield of the prepared rice bran oil is 85.73%, and the acid value is 3.51 mg KOH / g.

[0032] Example 4 (1) Pretreatment: Sieve fresh rice bran through a 20-mesh sieve to remove broken particles and impurities.

[0033] (2) Stabilization: The rice bran in step (1) is placed in a high-temperature and high-humidity gas jet impact for stabilization treatment, with the parameters set as time 3 min, relative humidity 25%, wind speed 10±0.5 m / s, and temperature 110°C.

[0034] (3) Ultrasonic combined high-energy medium mill grinding: 1.2 kg of rice bran and 10.8 kg of distilled water in step (2) were mixed and placed in the stirring cylinder of an ultrasonic combined high-energy medium mill for grinding for 2.5 h. The grinding process was accompanied by ultrasonic treatment, and the temperature of the entire system was kept below 30 °C. The parameters were set as follows: speed of 1200 r / min, diameter of grinding beads (zirconia) of 0.6 mm, filling degree of grinding chamber of 75%, and power of ultrasonic treatment of 300 W.

[0035] (4) Demulsification: Add the rice bran emulsion in step (2) to a saturated sodium chloride solution in a volume ratio of 1:2, then adjust the pH of the emulsion to 4.5 with hydrochloric acid, stir for 40 min, and centrifuge for 30 min at 4800 r / min. The upper oil layer is the rice bran oil. The yield of the prepared rice bran oil is 86.41%, and the acid value is 3.46 mg KOH / g.

[0036] Comparative Example 1: (1) Pretreatment: Sieve fresh rice bran through a 20-mesh sieve to remove broken particles and impurities.

[0037] (2) Stabilization: The rice bran in step (1) is placed in a high-temperature and high-humidity gas jet impact for stabilization treatment, with the parameters set as time 3 min, relative humidity 25%, wind speed 10±0.5 m / s, and temperature 110°C.

[0038] (3) High-energy medium mill grinding: 1.2 kg of rice bran and 10.8 kg of distilled water were mixed in step (2) and placed in the stirring cylinder of the high-energy medium mill for grinding for 2.5 h. The temperature of the entire system was kept below 30 °C. The parameters were set as follows: speed of 1200 r / min, diameter of grinding beads (zirconia) of 0.6 mm, and filling degree of the grinding chamber of 75%.

[0039] (4) Demulsification: Add the rice bran emulsion in step (2) to a saturated sodium chloride solution at a volume ratio of 1:2, then adjust the pH of the emulsion to 4.5 with hydrochloric acid, stir for 40 min, and centrifuge for 30 min at 4800 r / min. The upper oil layer is the rice bran oil. The yield of the prepared rice bran oil is 60.16%, and the acid value is 3.75 mg KOH / g.

[0040] Comparative Example 2 (1) Pretreatment: Sieve fresh rice bran through a 20-mesh sieve to remove broken particles and impurities.

[0041] (2) Stabilization: The rice bran in step (1) is placed in a high-temperature and high-humidity gas jet impact for stabilization treatment, with the parameters set as time 3 min, relative humidity 25%, wind speed 10±0.5 m / s, and temperature 110°C.

[0042] (3) Ultrasonic treatment: 1.2 kg of rice bran and 10.8 kg of distilled water were mixed in a stirring tank and ultrasonicated for 2.5 h. The temperature of the whole system was kept below 30 °C. The power of ultrasonic treatment was 300 W.

[0043] (4) Demulsification: Add the rice bran emulsion in step (2) to a saturated sodium chloride solution in a volume ratio of 1:2, then adjust the pH of the emulsion to 4.5 with hydrochloric acid, stir for 40 min, and centrifuge for 30 min at 4800 r / min. The upper oil layer is the rice bran oil. The yield of the prepared rice bran oil is 10.16%, and the acid value is 3.68 mg KOH / g.

[0044] Comparative Example 3: (1) Pretreatment: Sieve fresh rice bran through a 20-mesh sieve to remove broken particles and impurities.

[0045] (2) Stabilization: The rice bran in step (1) is placed in a high-temperature and high-humidity gas jet impact for stabilization treatment, with the parameters set as time 3 min, relative humidity 25%, wind speed 10±0.5 m / s, and temperature 110°C.

[0046] (3) Ultrasonic treatment: 1.2 kg of rice bran and 10.8 kg of distilled water were mixed in a stirring tank and ultrasonicated for 2.5 h. The temperature of the whole system was kept below 30 °C. The power of ultrasonic treatment was 300 W.

[0047] (4) High-energy medium mill grinding: The rice bran suspension after ultrasonic treatment in step (3) was placed in the stirring cylinder of a high-energy medium mill and ground for 2.5 h. The temperature of the entire system was maintained below 30 °C. The parameters were set as follows: rotation speed of 1200 r / min, grinding bead (zirconia) diameter of 0.6 mm, and grinding chamber filling degree of 75%.

[0048] (5) Demulsification: Add the rice bran emulsion in step (2) to a saturated sodium chloride solution in a volume ratio of 1:2, then adjust the pH of the emulsion to 4.5 with hydrochloric acid, stir for 40 min, and centrifuge for 30 min at 4800 r / min. The upper oil layer is the rice bran oil. The yield of the prepared rice bran oil is 67.93%, and the acid value is 3.84 mg KOH / g.

[0049] Comparative Example 4: (1) Pretreatment: Sieve fresh rice bran through a 20-mesh sieve to remove broken particles and impurities.

[0050] (2) Ultrasonic combined high-energy medium mill grinding: 1.2 kg of rice bran and 10.8 kg of distilled water in step (2) were mixed and placed in the stirring cylinder of an ultrasonic combined high-energy medium mill for grinding for 2.5 h. The grinding process was accompanied by ultrasonic treatment, and the temperature of the entire system was kept below 30 °C. The parameters were set as follows: speed of 1200 r / min, diameter of grinding beads (zirconia) of 0.6 mm, filling degree of grinding chamber of 75%, and power of ultrasonic treatment of 300 W.

[0051] (3) Demulsification: Add the rice bran emulsion in step (2) to a saturated sodium chloride solution at a volume ratio of 1:2, then adjust the pH of the emulsion to 4.5 with hydrochloric acid, stir for 40 min, and centrifuge at 4800 r / min for 30 min. The upper oil layer is the rice bran oil. The yield of the prepared rice bran oil is 77.16%, and the acid value is 46.92 mg KOH / g.

[0052] Comparative Example 5: (1) Pretreatment: Sieve fresh rice bran through a 20-mesh sieve to remove broken particles and impurities.

[0053] (2) Stabilization: The rice bran in step (1) is placed in a direct steam heating device for stabilization treatment, with the parameters set as time 3 min, relative humidity 25%, wind speed 10±0.5 m / s, and temperature 110°C.

[0054] (3) Ultrasonic combined high-energy medium mill grinding: 1.2 kg of rice bran and 10.8 kg of distilled water in step (2) were mixed and placed in the stirring cylinder of an ultrasonic combined high-energy medium mill for grinding for 2.5 h. The grinding process was accompanied by ultrasonic treatment, and the temperature of the entire system was kept below 30 °C. The parameters were set as follows: speed of 1200 r / min, diameter of grinding beads (zirconia) of 0.6 mm, filling degree of grinding chamber of 75%, and power of ultrasonic treatment of 300 W.

[0055] (4) Demulsification: Add the rice bran emulsion in step (2) to a saturated sodium chloride solution in a volume ratio of 1:2, then adjust the pH of the emulsion to 4.5 with hydrochloric acid, stir for 40 min, and centrifuge for 30 min at 4800 r / min. The upper oil layer obtained is the rice bran oil. The yield of the prepared rice bran oil is 79.51%, and the acid value is 35.27 mg KOH / g.

[0056] Comparative Example 6: (1) Pretreatment: Sieve fresh rice bran through a 20-mesh sieve to remove broken particles and impurities.

[0057] (2) Stabilization: The rice bran in step (1) is placed in a high-temperature and high-humidity gas jet impact for stabilization treatment, with the parameters set as time 3 min, relative humidity 25%, wind speed 10±0.5 m / s, and temperature 110°C.

[0058] (3) Ultrasonic combined high-energy medium mill grinding: 1.2 kg of rice bran and 10.8 kg of distilled water in step (2) were mixed and placed in the stirring cylinder of an ultrasonic combined high-energy medium mill for grinding for 2.5 h. The grinding process was accompanied by ultrasonic treatment, and the temperature of the entire system was kept below 30 °C. The parameters were set as follows: speed of 1200 r / min, diameter of grinding beads (zirconia) of 0.6 mm, filling degree of grinding chamber of 75%, and power of ultrasonic treatment of 300 W.

[0059] (4) Demulsification: Add distilled water to the rice bran emulsion in step (2) at a volume ratio of 1:6, then adjust the pH of the emulsion to 4.5 with hydrochloric acid, stir for 40 min, and centrifuge at 4800 r / min for 30 min. The upper oil layer is the rice bran oil. The yield of the prepared rice bran oil is 60.37%, and the acid value is 3.85 mg KOH / g.

[0060] Comparative Example 7 (1) Pretreatment: Sieve fresh rice bran through a 20-mesh sieve to remove broken particles and impurities.

[0061] (2) Stabilization: The rice bran in step (1) is placed in a high-temperature and high-humidity gas jet impact for stabilization treatment, with the parameters set as time 3 min, relative humidity 25%, wind speed 10±0.5 m / s, and temperature 110°C.

[0062] (3) Ultrasonic combined high-energy medium mill grinding: 1.2 kg of rice bran and 10.8 kg of distilled water in step (2) were mixed and placed in the stirring cylinder of an ultrasonic combined high-energy medium mill for grinding for 2.5 h. The grinding process was accompanied by ultrasonic treatment, and the temperature of the entire system was kept below 30 °C. The parameters were set as follows: speed of 1200 r / min, diameter of grinding beads (zirconia) of 0.6 mm, filling degree of grinding chamber of 75%, and power of ultrasonic treatment of 300 W.

[0063] (4) Demulsification: The rice bran in step (2) was stirred for 40 min and then centrifuged at 4800 r / min for 30 min. The upper oil layer obtained was the rice bran oil. The yield of the prepared rice bran oil was 18.16% and the acid value was 3.64 mg KOH / g.

[0064] Embodiment 5: In this example, the yield, acid value, oryzanol and vitamin E of the rice bran oil obtained in the above examples 1-4 and comparative examples 1-6 were measured and analyzed, and the specific process is as follows: (1) Determination of rice bran oil yield: (2) Determination of acid value of rice bran oil: The acid value of rice bran oil was determined according to the method in GB 5009.229-2016.

[0065] (3) Determination of oryzanol and vitamin E in rice bran oil: Determine according to the method of LS / T 6121.1-2017.

[0066] The above measurement results are shown in Table 1: Table 1 Results of determination of rice bran oil quality indicators As can be seen from the above table, the high-temperature and high-humidity gas jet impact technology is used for stabilization and combined with ultrasonic-high-energy medium mill grinding, and then salt and acid are used for demulsification. The yield of rice bran oil prepared reaches 86.41%, the acid value is greatly reduced, the loss of active ingredients is small, and the overall quality of rice bran oil is greatly improved. In addition, if the high-temperature and high-humidity gas jet impact technology or the traditional direct steam heating method is not used for stabilization treatment, the acid value of the prepared rice bran oil is high and the quality is poor. Secondly, the high-energy medium mill alone or the ultrasonic treatment alone will result in less dissolution of rice bran oil.

[0067] In summary, under the conditions of the present invention, high-temperature and high-humidity gas jet impact technology can be used for stabilization, combined with ultrasonic-high-energy medium grinding, and then salt and acid demulsification technology can be used to achieve high-yield and high-quality rice bran oil preparation. The process is simple and easy to realize industrial production, and has broad application prospects.

[0068] The embodiments of the present application are described above in conjunction with the accompanying drawings. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the core idea of ​​the present application, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the inspiration of the present application, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present application and the claims, all of which are within the protection of the present application.

Claims

1. A method for preparing rice bran oil, characterized in that, The following steps are involved: The rice bran is stabilized by high temperature and high humidity gas jet impact; The stabilized rice bran is mixed with water and then treated with ultrasound combined with high-energy medium mill for 120 min to 150 min to obtain a rice bran emulsion; The rice bran emulsion and the salt solution are mixed, and then acid is added to adjust the pH to 4.5, stirred, and centrifuged to obtain the rice bran oil.

2. The preparation method according to claim 1, characterized in that: The parameters of the high temperature and high humidity gas jet impact treatment are: relative humidity 25%-30%, wind speed 10±0.5 m / s, temperature 100-120°C, and time 2-3 min.

3. The preparation method according to claim 1, characterized in that: The specific process parameters of the ultrasonic combined high-energy medium mill are as follows: the rotation speed is 1200 r / min, the diameter of the grinding beads is 0.6 mm, the filling degree of the grinding chamber is 70%-80%, and the power of the ultrasonic treatment is 300 W.

4. The preparation method according to claim 3, characterized in that: The temperature of the high energy medium mill during grinding is less than 30°C.

5. The preparation method according to claim 1, characterized in that: The dosage ratio of rice bran to water is 1 g:8mL-12 mL.

6. The preparation method according to claim 1, characterized in that: The salt solution is a sodium chloride solution, and the volume ratio of the sodium chloride solution to the rice bran emulsion is 1:1-2.

7. The preparation method according to claim 1, characterized in that: The acid is a citric acid solution or a hydrochloric acid solution.

8. The preparation method according to claim 1, characterized in that: The stirring time is 30 min-40 min; the centrifugal speed is 4800 r / min, and the time is 30 min.

9. A rice bran oil, characterized in that The invention is prepared by the preparation method according to any one of claims 1 to 8.

10. Rice bran oil according to claim 9, characterized in that The acid value of the rice bran oil is ≤4 mgKOH / g.

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