Ternary coupling rice bran fatty acid oxidation inhibition and control method

Abstract

The invention relates to a ternary coupling rice bran fatty acid oxidation inhibition and control method. Comprising the following steps: screening fresh rice bran through a funnel, sieving, cleaning the fresh rice bran with clear water, filtering and drying; the dried rice bran and mushroom residues with the mass fraction being 5%-10% are mixed to be uniform, a natural antioxidant is added, the adding amount of the natural antioxidant is 0.01%-0.1% of the mass of the rice bran, and a rice bran mixed material is obtained; bagging the rice bran mixed material, introducing high-purity nitrogen into a bag, establishing a preliminary inert gas environment, reducing the pressure in the bag to be less than or equal to 5Pa, and forming a high-vacuum environment; and performing microwave coupling dry heat treatment on the rice bran mixed material treated in the step S3. The condition avoids the problems of enzyme molecule residual activity and insufficient extremely heat caused by non-uniform microwave energy, and realizes efficient inactivation of multiple oxidation related enzymes such as lipase, catalase and lipoxygenase.

Description

Technical Field

[0001] The invention belongs to the technical field of agricultural product processing and preservation, in particular to a ternary coupled rice bran fatty acid oxidation inhibition and control method. Background Art

[0002] Rice bran accounts for about 8%-10% of the total weight of rice. It is rich in unsaturated fatty acids and a variety of nutritional and chemically active ingredients, and plays a significant role in preventing hypertension, hyperglycemia, and arteriosclerosis. However, because rice bran is rich in oils and fats, lipase breaks through the cell compartments after processing and reacts with oils and fats very quickly without treatment, and the generated free fatty acids are peroxidized in an oxygen-containing environment, causing the flavor of rice bran to deteriorate, the nutritional quality to decline, and the functional properties to deteriorate.

[0003] In recent years, microwave treatment technology has been widely used to inhibit the oxidation of rice bran fatty acids. Under the action of the microwave electromagnetic field, the dipole moment of the water molecules in the rice bran vibrates rapidly with the alternation of the electric field, resulting in mutual collision and friction between the molecules, thereby generating instantaneous extreme heat to inhibit the activity of enzymes related to fatty acid oxidation. Water molecules are important participating factors in fat hydrolysis reactions, an important source of thermal effects during microwave treatment, and the main medium for heat conduction. Improper regulation of microwave intensity on their activity will directly lead to increased fat hydrolysis. Moderate microwave intensity produces extreme heat to inhibit enzyme activity, and the molecular escape of water molecules after overactivity plays a role in suppressing fatty acid oxidation. The current method of using microwave treatment in the industry to inhibit the oxidation of rice bran fatty acids has the following shortcomings:

[0004] 1. The efficiency of microwave treatment in inhibiting enzyme activity in rice bran is limited: One of the main causes of fatty acid oxidation in rice bran is the activity of lipase. Microwave treatment destroys the active center of the enzyme by rapid heating, thereby inhibiting lipid hydrolysis catalyzed by lipase. However, the uneven distribution of microwave energy inside the substance may result in insufficient extreme heat or insufficient denaturation of some enzyme molecules. This selective inhibition may cause the remaining lipase to still function during subsequent storage. In addition, the inhibitory effect of microwaves on other oxidation-related enzymes (such as catalase and lipoxygenase) is also incomplete, which may indirectly accelerate fatty acid oxidation. Therefore, it is difficult for microwave treatment to comprehensively solve the problem of enzymatic oxidation.

[0005] 2. Microwave treatment has limited control over free radical generation and oxidation reaction chain: Microwave treatment has a weak effect on free radical generation and fatty acid auto-oxidation chain reaction in rice bran. Reactive oxidative species (ROS) and free radicals are generated during fatty acid oxidation, which promote the expansion of the oxidation reaction chain. Microwaves mainly destroy molecular structures through thermal effects rather than directly removing free radicals. In addition, the microwave-induced environment may change the electron density at the double bonds of fatty acids, further increasing their reactivity to oxygen. This potential negative effect may intensify the initial oxidation reaction.

[0006] 3. Microwave treatment does not adequately inhibit the formation of lipid oxidation products in rice bran: The end products of fatty acid oxidation, such as aldehydes and ketones, have high chemical stability, and microwave treatment has a weak inhibitory effect on their formation. From a molecular perspective, the thermal effect of microwave treatment mainly acts on weak bonds in fat molecules (such as hydrogen bonds and van der Waals forces), and cannot effectively inhibit the breaking and recombination of strong bonds during fatty acid oxidation. In addition, hydroxyl groups (-OH) in phenolic substances are prone to react with oxygen molecules or other reactive species (such as free radicals) in the environment, resulting in structural breakage or oxidative degradation. Therefore, natural antioxidants in rice bran (such as phenolic compounds) may degrade during microwave treatment, further weakening the ability to inhibit lipid oxidation products, resulting in an increased risk of deterioration in the flavor and quality of rice bran oil.

[0007] Chinese patent publication number: CN112568360A discloses a method for stabilizing enzyme inactivation in selenium-rich rice bran, wherein the method treats the rice bran with microwaves, seals the rice bran in a plastic bag while it is still hot, and then cools it. The method uses the moisture vapor generated by microwave treatment to quickly seal it in a plastic packaging bag to overcome the problem that traditional microwave treatment easily leads to uneven heating and different enzyme inactivation effects in the inner and outer layers of rice bran. However, sealing the heated rice bran in a plastic packaging bag while it is still hot may cause the packaging bag to release toxic substances, thereby affecting the edible value of the rice bran.

[0008] Chinese Patent Publication No.: CN104304444A discloses a method for continuous stabilization of rice bran by tunnel microwave. However, this method has oxygen in the presence of microwave treatment, and cannot avoid the initial oxidation reaction of rice bran fatty acids caused by the presence of oxygen during the heating process. In addition, microwave treatment has relatively limited inhibition on enzyme activity when treating large quantities of rice bran, thereby affecting the inhibitory effect on the oxidation of rice bran fatty acids. In addition, it is mentioned that this method can preserve the original good nutrients of rice bran. However, during microwave treatment, the hydroxyl group (-OH) of phenolic substances in rice bran is easy to react with oxygen molecules or other reactive species (such as free radicals) in the environment, resulting in structural fracture or oxidative degradation, which reduces the content of phenolic substances. Summary of the invention

[0009] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a ternary coupled rice bran fatty acid oxidation inhibition and control method, the purpose is to overcome the shortcomings of the prior art such as limited inhibition efficiency of microwave treatment on enzyme activity, insufficient inhibition of the generation of lipid oxidation products, limited control ability of free radical generation and oxidation reaction chain, etc., aiming to obtain the best way to inhibit the oxidation of rice bran fatty acids and provide new ideas and methods for the industrialization and high-value utilization of rice bran.

[0010] The present invention solves the technical problem by adopting the following technical solutions:

[0011] A ternary coupled rice bran fatty acid oxidation inhibition and control method comprises the following steps:

[0012] S1, sieving fresh rice bran through a funnel, sieving, washing the fresh rice bran with clean water, filtering, and drying;

[0013] S2, mixing the dried rice bran with 5%-10% of mushroom residues, and adding a natural antioxidant, wherein the amount of the natural antioxidant added is 0.01%-0.1% of the mass of the rice bran, to obtain a rice bran mixture;

[0014] S3, bagging the rice bran mixture, introducing high-purity nitrogen into the bag, establishing a preliminary inert gas environment, reducing the pressure in the bag to ≤5Pa, and forming a high vacuum environment;

[0015] S4, subjecting the rice bran mixture processed in step S3 to microwave-coupled dry heat treatment.

[0016] Moreover, fresh rice bran processed within 5 hours was selected as the raw material, and the raw material was sieved through a 40-mesh sieve funnel.

[0017] Furthermore, the natural antioxidant is ferulic acid.

[0018] Moreover, it includes a vacuum cavity, a funnel, a multi-layer transport conveyor belt, a temperature sensor, a circulating fan, a vacuum pump, a microwave generating module, a dry heat treatment module and a control system; the vacuum cavity is rectangular and arranged in a horizontal direction, a sealing cover is arranged at the top center of the vacuum cavity, the top of the sealing cover is connected to the funnel, the opening of the funnel is connected to the multi-layer transport conveyor belt, and a temperature sensor is also arranged on the top of the vacuum cavity; an air inlet and an air outlet are respectively arranged on the two side walls of the vacuum cavity, the air inlet is connected to the air outlet end of the circulating fan, and the air outlet is connected to the air inlet end of the circulating fan to form a closed-loop air path; a vacuum interface is also opened on one side wall of the vacuum cavity, and the vacuum interface is connected to the vacuum pump through a pipeline; a microwave generating module and a control system are respectively arranged on the outer wall of the vacuum cavity, and a dry heat treatment module is arranged at the bottom of the vacuum cavity.

[0019] Moreover, it also includes a gas control module, which is arranged in series with the circulation fan and is used to adjust the circulation wind speed and introduce inert gas.

[0020] Moreover, the rotation speed of the circulating fan is 100-3000rpm.

[0021] Moreover, the flow rate of the gas in the gas control module is 10-600 mL / min.

[0022] Moreover, the dry heat module realizes heat supply by an electric heating element arranged at the bottom of the vacuum cavity, and the dry heat module is equipped with 6-18 groups of high-efficiency heat-conducting elements.

[0023] Moreover, the material of the vacuum cavity is a high-strength stainless steel lining insulation layer, and the inner layer of the vacuum cavity is 3-5 layers of composite nano thermal insulation material.

[0024] Moreover, the low pressure environment in the vacuum chamber is ≤5Pa.

[0025] The advantages and positive effects of the present invention are:

[0026] 1. The vacuum microwave combined dry heat equipment in the present invention can heat rice bran quickly at a certain temperature by reducing the environmental pressure, generating extremely hot and evenly distributed microwave energy. This condition avoids the problem of residual activity of enzyme molecules and insufficient extreme heat caused by uneven microwave energy, and achieves efficient inactivation of various oxidation-related enzymes such as lipase, catalase and lipoxygenase. The high vacuum environment can slow down the heat loss during heat conduction, improve the efficiency of microwave and dry heat treatment, promote the comprehensive destruction of hydrogen bonds and hydrophobic interactions of enzyme proteins, and achieve a more comprehensive enzymatic oxidation inhibition effect.

[0027] 2. The vacuum environment in the present invention significantly reduces the oxygen concentration, reduces the necessary oxidant supply of the fatty acid oxidation reaction, and slows down the potential negative effect that may aggravate the initial oxidation reaction. At the same time, the combined dry heat treatment can avoid inducing the activation of fatty acid double bonds by regulating the reaction temperature and reaction time, thereby reducing the generation of reactive oxidative species (ROS) and free radicals. The fatty acid oxidation chain reaction depends on the diffusion and regeneration of free radicals. The dry heat treatment can reduce the initial rate of free radical generation and slow down the expansion rate of the reaction chain. Some non-volatile by-products (such as cross-linked polymers) generated during the dry heat treatment process can react with reactive oxidative species (ROS), reduce their concentration in the reaction system, and then reduce the reaction rate constant, change the kinetic parameters of fatty acid oxidation, and make the lipid chemical bonds in rice bran more stable.

[0028] 3. The vacuum environment in the present invention changes the molecular collision frequency and the regeneration process of free radicals, delays the formation of reactive intermediates, and this low oxygen environment can also reduce the contact probability of lipid molecule double bonds with oxygen molecules, thereby inhibiting the generation of oxidation products such as aldehydes and ketones. At the same time, the combination of dry heat and vacuum microwaves helps to protect the natural antioxidants in rice bran during heating, slows down its decomposition rate, and dry heat treatment promotes the molecular rearrangement of the compound and enhances its intramolecular stability, such as forming more covalent bonds or cross-linked structures to effectively retain the activity of phenolic components, thereby forming secondary protection for fatty acid oxidation. The vacuum environment also reduces the intermolecular collision frequency, reduces the possibility of thermal decomposition of phenolic substances, and the low oxygen partial pressure under vacuum state also helps to maintain the activity of natural antioxidants, and also indirectly and effectively retains the active ingredients of phenolic substances, further enhancing the inhibitory effect on oxidation reactions.

[0029] 4. Compared with the single dry heat treatment and microwave treatment, the microwave combined dry heat treatment of the present invention greatly reduces the total treatment time, improves the energy utilization efficiency, and reduces the production cost. According to the calculation of treating 100kg of rice bran, the activity of rice bran lipase is reduced to 20%. When treating 100kg of rice bran, the dry heat combined with microwave treatment consumes only 8kWh of electricity, which can save 47% of energy consumption compared with single microwave treatment (15kWh), and can save 60% of energy consumption compared with single dry heat treatment (20kWh), showing higher energy efficiency and economy overall.

[0030] 5. The oil in the rice bran of the present invention is rich in unsaturated fatty acids and is prone to lipid peroxidation. Ferulic acid can inhibit all stages of lipid peroxidation, including the free radical initiation reaction in the initial stage, the peroxide free radical generation reaction in the propagation stage, and the peroxidation product generation reaction in the termination stage. Through this multi-stage inhibition, the generation of lipid peroxidation products such as malondialdehyde in rice bran can be significantly reduced, the oil component in rice bran is effectively protected, and the shelf life of rice bran mixed materials is extended.

[0031] 6. The phenolic compounds in the mushroom residue of the present invention can react with active oxygen free radicals such as hydroxyl free radicals and superoxide anion free radicals generated in the rice bran during processing and storage, thereby reducing the chance of unsaturated fatty acids in the rice bran being attacked by free radicals and inhibiting fatty acid oxidation reactions. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the ternary coupling device of the present invention.

[0033] Figure 2 This is a graph showing changes in rice bran lipase activity under single / combination treatments of the present invention. Different letters on each group of data indicate significant differences among the groups (p<0.05).

[0034] Figure 3 This is a graph showing changes in rice bran lipoxygenase activity under single / combination treatments of the present invention. Different letters on each group of data indicate significant differences among the groups (p<0.05).

[0035] Figure 4 This is a graph showing changes in the fatty acid values ​​of rice bran under the single / combination treatments of the present invention. Different letters on the data sets indicate significant differences among the groups (p<0.05).

[0036] Figure 5 This is a graph showing changes in carbonyl values ​​of rice bran under single / combination treatments of the present invention. Different letters on the data of each group indicate significant differences among the groups (p<0.05).

[0037] Figure 6 This is a graph showing changes in the total number of rice bran colonies under the single / combination treatments of the present invention. Different letters on each group of data indicate significant differences among the groups (p<0.05).

[0038] Figure 7 This is a graph showing changes in the peroxide value of rice bran under vacuum / non-vacuum treatment according to the present invention. Different letters on each group of data indicate significant differences among the groups (p<0.05).

[0039] Figure 8 This is a graph showing changes in malondialdehyde in rice bran under vacuum / non-vacuum treatment according to the present invention. Different letters on each group of data indicate significant differences among the groups (p<0.05).

[0040] Fig. 9 The figure is a graph showing the change of free phenol / bound phenol content in rice bran under different treatments of the present invention. Different letters on each group of data indicate significant differences among the groups (p<0.05).

[0041] Reference numerals

[0042] 1- multi-layer transport conveyor belt, 2- funnel, 3- vacuum chamber, 4- microwave generating module, 5- dry heat treatment module, 6- circulating fan, 7- vacuum pump, 8- gas control module, 9- temperature sensor, 10- control system. DETAILED DESCRIPTION

[0043] The present invention is further described in detail below through specific examples. The following examples are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereto.

[0044] The "three-way" in the three-way coupled rice bran fatty acid oxidation inhibition and control method of the present invention refers to the synergistic coupling of microwave, vacuum and dry heat. Fresh rice bran within 5 hours after processing is selected as raw material. The material needs to be screened by a 40-mesh screen funnel 2 to remove rice husk debris and other foreign particles, optimize its particle size distribution, and avoid the interference of impurities on the subsequent treatment effect. Then, the fresh rice bran is washed with clean water, filtered, and dried; the dried rice bran is evenly mixed with mushroom residues with a mass fraction of 5%-10% (the mushroom residue used in the present invention is red pine mushroom residue), and natural antioxidant ferulic acid is added, and the addition amount of ferulic acid is 0.01%-0.1% of the mass of the rice bran to obtain a rice bran mixed material; then the rice bran mixed material is bagged, and then, a circulating fan 6 is started to introduce high-purity nitrogen into the bag, the material is fully purged, and the residual oxygen in the bag and on the surface of the material is quickly removed to establish a preliminary inert gas environment, and the pressure in the bag is reduced to ≤5Pa by starting a vacuum pump 7 to form a high vacuum environment. The low oxygen condition further inhibits the oxidation reaction and provides a stable environmental foundation for the subsequent heat treatment. Then, microwave coupling dry heat treatment is carried out. The microwave treatment adopts the upper and lower double-sided wave source design. The microwave energy generated by the microwave generator per unit time is 0.2kW-1.5kW, the wavelength is set to 1mm-1m, and the treatment time is set to 1-5min. The band is optimized to ensure the efficient absorption and uniform distribution of electromagnetic waves in the material. The heating temperature of the dry heat treatment heat source is set to 120℃-130℃, and the treatment time is 5-10min.

[0045] A ternary coupled rice bran fatty acid oxidation inhibition and control method comprises the following steps:

[0046] S1. Preparation before operation: Lay the material to be processed evenly on the multi-layer conveyor belt for transportation, ensuring that the thickness is moderate to avoid uneven heating. Equipment inspection, check the connection status of the sealing cover, airtight gasket, and air inlet and outlet of the vacuum chamber 3 to ensure no leakage. Verify the normal working status of the microwave generating module 4, dry heat treatment module 5, vacuum pump 7, circulating fan 6 and sensor. Confirm whether the gas control module 8 is connected to a suitable inert gas (such as nitrogen). Enter the processing parameters through the control panel, including vacuum degree, microwave power, heating temperature, time, circulating wind speed, gas flow rate, etc. In addition, the device can also select corresponding programs according to the different characteristics of the materials, such as low temperature and long time mode (suitable for sensitive materials) or high temperature and fast mode (suitable for high temperature resistant materials).

[0047] S2, operation stage: the multi-layer conveyor belt is started, and the rice bran is passed through a 40-mesh sieve to remove rice husk fragments, incompletely processed rice grains, and mixed foreign particles. The vacuum environment is established, and the vacuum pump 7 is started to quickly extract the air in the cavity to establish a set low-pressure environment (such as 0-5Pa). After the vacuum degree reaches the target value, the gas control module 8 is started to maintain the vacuum state to prevent external air from entering the cavity. Microwave treatment and dry heat treatment, the microwave generation module 4 is started to uniformly heat the material with the set power. Microwaves induce molecular polarization to generate heat from the inside of the material, effectively improving the heating efficiency. At the same time, the dry heat treatment module 5 is started to provide uniform external heat through the bottom and side walls of the cavity to form an internal and external synergistic heating environment. The temperature sensor 9 monitors the parameters in the cavity in real time and feeds back to the control system 10 to dynamically adjust the microwave power and dry heat temperature to avoid overheating or overdrying. Gas circulation adjustment, the circulating fan 6 is started to guide the inert gas (such as nitrogen) to flow in the cavity, dissipate heat through uniform airflow, inhibit oxidation reactions, and discharge residual oxygen. If there is water evaporation in the cavity, the circulating fan 6 will discharge the moisture and replenish dry gas through the gas control module 8.

[0048] S3, end of operation and post-processing operations: cooling and exhausting. After the heating process is completed, the control system 10 reduces the power of the microwave and dry heat modules, and starts the cooling process to gradually discharge the gas in the cavity to prevent the material from being damaged by the sudden pressure change. Material removal. After the cavity returns to normal pressure, open the sealing cover and take out the processed material. Equipment cleaning and maintenance, clean the residue in the cavity, and check the cleanliness of the microwave generating module 4 and the heating element. Regularly calibrate the temperature sensor 9 and check the operating status of the vacuum pump 7.

[0049] The device of the ternary coupled rice bran fatty acid oxidation inhibition and control method of the present invention comprises a vacuum cavity 3, a funnel 2, a multi-layer transport conveyor belt 1, a temperature sensor 9, a circulating fan 6, a vacuum pump 7, a microwave generating module 4, a dry heat treatment module 5 and a control system 10; the vacuum cavity 3 is rectangular and arranged in a horizontal direction, a sealing cover is arranged at the top center of the vacuum cavity 3, the top of the sealing cover is connected to the funnel 2, the opening of the funnel 2 is connected to the multi-layer transport conveyor belt 1, and a temperature sensor 9 is also arranged at the top of the vacuum cavity 3; by real-time monitoring of temperature changes in the cavity, accurate data is provided for the control system 10. An air inlet and an air outlet are respectively arranged on the two side walls of the vacuum chamber 3, the air inlet is connected to the air outlet end of the circulating fan 6, and the air outlet is connected to the air inlet end of the circulating fan 6 to form a closed-loop air path; a vacuum interface is also arranged on one side wall of the vacuum chamber 3, and the vacuum interface is connected to the vacuum pump 7 through a pipeline; the vacuum pump 7 can draw air from the inside of the cavity to form a low-pressure environment, and the vacuum pump 7 is automatically adjusted by the gas control module 8 according to the environment during operation to maintain a constant vacuum degree in the cavity.

[0050] The outer wall of the vacuum cavity 3 is provided with a microwave generating module 4 and a control system 10. The microwave generating device sends microwave radiation to the inside of the cavity through a microwave waveguide device, and can perform non-contact heating on the material in the cavity; the control system 10 is equipped with a microprocessor, which can fine-tune the microwave, dry heat treatment intensity and the operating state of the vacuum pump 7 to ensure that the device is in the best working state. The sensing data is transmitted to the equipment control system 10 through a high-speed communication module, and the embedded advanced microprocessor performs data analysis and dynamic regulation. The processing system can accurately fine-tune the microwave power and heating temperature according to the feedback information to ensure that the material is heated evenly and avoid local overheating.

[0051] A dry heat treatment module 5 is arranged at the bottom of the vacuum cavity 3. The dry heat treatment module 5 realizes heat supply through an electric heating element arranged at the bottom of the cavity. The module is equipped with multiple sets of high-efficiency thermal conductive elements to ensure that the heat is evenly distributed inside the cavity, thereby avoiding local overheating of the material.

[0052] It also includes a gas control module 8, which is arranged in series with the circulation fan 6 and is used to adjust the circulation wind speed and introduce inert gas (such as nitrogen) to inhibit oxidation reaction and improve heating efficiency.

[0053] The entire device adopts a sealed design, using high-strength rubber gaskets and flange structures to ensure the airtightness of the vacuum chamber 3. At the same time, the entire device uses a modular design, and all components can be disassembled and replaced, which is convenient for maintenance and upgrading.

[0054] Example 1

[0055] A ternary coupled rice bran fatty acid oxidation inhibition and control method, the embodiment of the present invention is a test method:

[0056] (1) Lipase activity

[0057] Accurately weigh 12g of rice bran in each treatment group and place it in a 50mL centrifuge tube, add 10mL of 0.1mol / L sodium phosphate buffer solution of pH=7, ultrasonically oscillate at 25°C for 40min, centrifuge the mixed solution at 4000r / min for 10min, and the supernatant is the rice bran lipase extract. Take 0.2mL of supernatant in another 50mL centrifuge tube, add 0.2mL of solution A (0.1g PNPL dissolved in 30mL isopropanol) and 3mL of solution B (0.4g Triton X-100+0.1g gum arabic dissolved in 90mL 0.1mol / L sodium phosphate buffer solution of pH=7), vortex mix and place at 35°C ultrasonic oscillation reaction for 45min, then place in a boiling water bath to kill enzyme for 20min, cool, centrifuge at 5000r / min for 10min, take the supernatant and measure absorbance at 410nm. The rice bran activity of the blank control is set as 100%. The enzymatic activity and residual activity of lipase are calculated as follows:

[0058] Lipase activity = (A410 × 10) / W

[0059] Where: A410—absorbance; W—sample dry basis mass (g); 10—dilution multiple.

[0060] (2) Lipoxygenase activity

[0061] Weigh 1g of rice bran from each treatment group, add 20mL Tris-HCl buffer (0.05mol / L, pH 7.0), ultrasonically extract for 15min, centrifuge at 12000r / min for 15min at 4℃, take the supernatant and put it in a 4℃ refrigerator for later use. Using ultraviolet spectrophotometry, set the detection wavelength to 234nm, the detection time to 75s, record the data once every 15s, repeat 5 times to take the average value, and substitute the absorbance into the formula to calculate LOX activity. The activity of blank control rice bran is set to 100%. Calculate the lipoxygenase activity according to the following formula:

[0062] A=4×(OD 75s -OD 0s ) / 5 / 0.01

[0063] Where: A is the activity unit of lipoxygenase (U); OD 75s OD is the absorbance value of the reaction for 75 seconds; 0s is the absorbance value at the beginning of the reaction; 0.01 is a constant.

[0064] (3) Fatty acid value

[0065] Weigh 5g of rice bran from each treatment group into a conical flask, add 50mL of n-hexane, and shake at room temperature of 25°C for 30min. Let stand for 10min and filter. Take 25mL of filtrate and 25mL of phenolphthalein ethanol solution, and titrate with potassium hydroxide ethanol until it turns slightly red and the color does not fade within 30s. The volume of potassium hydroxide ethanol solution consumed is V. Take 25mL of phenolphthalein ethanol solution and titrate with potassium hydroxide ethanol solution. The volume of potassium hydroxide ethanol solution consumed is V0 (V0=0.05mL), which is used as the blank group. The fatty acid value is calculated according to the following formula:

[0066]

[0067] Where: V is the volume of potassium hydroxide ethanol consumed by the titration sample, mL; V0 is the volume of potassium hydroxide ethanol consumed by the blank group; N is the concentration of potassium hydroxide ethanol solution, mol / L; m is the mass.

[0068] (4) Carbonyl value

[0069] Accurately weigh 0.25g of rice bran sample, add toluene to make up to the volume in a 25mL volumetric flask, and shake well. Take the sample in the 5mL volumetric flask, place it in a 25mL colorimetric tube, add 5mL of 4.3% trichloroacetic acid in toluene solution and 5mL of 0.05% 2,4-dinitrophenylhydrazine in toluene solution, and shake well. After 30 minutes in a 60℃ water bath, take out and cool, add 4% potassium hydroxide-ethanol solution, add ethanol to the 25mL mark, shake well, leave at room temperature for 10 minutes, and then measure the absorbance at 453nm. The blank sample is distilled water. The carbonyl value is expressed as the number of millimoles of carbonyl compounds per 1kg of oil and fat, in mmol / kg. The results are calculated as follows:

[0070]

[0071] In the formula: A—absorbance; W—sample weight; 854—absorption coefficient; V1—total dilution volume; V2—volume used for measurement.

[0072] (5) Determination of total microbial colony count

[0073] Refer to the plate count method in GB4789.2-2016 "National Food Safety Standard Food Microbiology Test Total Colony Count Determination" for determination and calculation

[0074] (6) Fatty acid composition and content

[0075] Preparation of 37 kinds of fatty acid methyl ester mixed standard solution: Take 1 mg of fatty acid methyl ester mixed standard solution, add 1 mL of n-hexane, place it in a gas chromatography bottle and set aside.

[0076] Extraction and methylation of rice bran oil: Weigh 5g of rice bran, add 100mL of petroleum ether to a Soxhlet extractor, and extract for 12h. After the extraction, evaporate the solvent in a 60℃ water bath to obtain an oil sample. Then add 5mL of n-hexane, vortex and mix evenly, then add 10mL of 0.4mol / L potassium hydroxide-methanol solution in a 70℃ water bath and heat for 20min. After standing and stratifying, take the supernatant and place it in a gas chromatography bottle for later use.

[0077] GC conditions: HP-5MS quartz capillary column (30m×0.25mm, 0.25μm); carrier gas is nitrogen; flow rate is 1mL / min; split ratio is 30:1; injection port temperature is 230℃; initial column temperature is 160℃, maintained for 4min; heating program is 4℃ / min, heating to 175℃ and maintained for 3min; heating to 185℃ and maintained for 3min; heating to 230℃ and maintained for 4min.

[0078] MS conditions: interface temperature 230°C, ion source temperature 230°C, electron impact ion source (EI), electron energy 80 eV, mass spectrometry scanning range m / z 40-450.

[0079] Qualitative and quantitative analysis of fatty acids: The retention time of 37 fatty acid mixed standards and NIST mass spectrum library search were used to qualitatively analyze each substance, and the area normalization method was used to quantitatively analyze fatty acids using MASS HUNTER software.

[0080] (7) Determination of peroxide value

[0081] Refer to GB5009.227-2016 "National Food Safety Standard Determination of Peroxide Value in Food" for determination and calculation

[0082] (8) Determination of malondialdehyde

[0083] Accurately weigh 2g of rice bran and place it in a mortar. Add 5mL of 10% trichloroacetic acid solution and grind until homogenous. Add 25mL of 10% trichloroacetic acid solution and shake well, then centrifuge at 4000r / min for 10min. Take 4mL of supernatant and 4mL of 0.6% thiobarbituric acid, mix well, and boil in boiling water for 15min. Measure the absorbance of the cooling liquid at 450nm, 532nm and 600nm. The malondialdehyde content is calculated according to the following formula:

[0084]

[0085] Where: A 450 is the absorbance value at 450nm; A 532 is the absorbance value at 532nm; A 600 is the absorbance value at 600nm; m is the mass.

[0086] (9) Determination of phenolic substances

[0087] Extraction of free phenol: Take 3g sample, extract with 20mL ethanol (80%) three times, stir magnetically for 10min each time, then centrifuge at 4500r / min for 5min. Combine the supernatants, evaporate to dryness at 45℃, then dilute to 25mL volumetric flask with 80% ethanol, and store at 4℃.

[0088] The method of extracting the combined phenol is as follows: the residue after the free phenol is extracted is dried, 1 g is weighed, 15 mL of n-hexane is added, the mixture is mixed and then centrifuged, the supernatant is decanted, 40 mL of NaoH (2 mol / L) is added, the mixture is sealed with nitrogen, and the mixture is digested on a shaker at 40°C for 4 h, and then the pH is adjusted to 2 with 2 mol / L HCl. The supernatant is transferred to a separatory funnel, the residue is washed with 10 mL of ultrapure water and centrifuged, the supernatants are combined, and the mixture is extracted three times with 10 mL of ethyl acetate. The ethyl acetate layers are combined, evaporated to dryness at 40°C, and then dissolved in 50% methanol to a 5 mL volumetric flask, and stored at 4°C.

[0089] Determination of free phenol / bound phenol content: Add 1 mL of ultrapure water to a 10 mL colorimetric tube, then add 250 μL of polyphenol extract and 250 μL of Folin phenol reagent, react at room temperature for 6 minutes, then add 2.5 mL of Na2CO3 (70 mg / mL) solution to terminate the reaction. Then add ultrapure water to the scale and mix evenly. After 90 minutes of storage in the dark, measure the absorbance at 760 nm. The blank sample is distilled water. Gallic acid is used as the standard, and the total phenol content is expressed as the gallic acid equivalent contained in 1 g of sample (dry weight), in mg / gd.b.

[0090] Example 2

[0091] A ternary coupled rice bran fatty acid oxidation inhibition and control method comprises the following steps:

[0092] The rice bran to be processed is placed on a multi-layer transport conveyor belt, the low pressure environment is set to 5 pa, the circulating fan speed is 1000 rpm, the gas is selected as nitrogen, the flow rate is selected as 200 mL / min, the microwave power is 0.6 kW, the wavelength is 1 m, the time is 1 min, the dry heat temperature is 130 ° C, the time is 5 min, the heat conductive element is 8 groups, and then the instrument is started to complete the treatment. The vacuum combined treatment group 1 (L1) is obtained.

[0093] Example 3

[0094] A ternary coupled rice bran fatty acid oxidation inhibition and control method comprises the following steps:

[0095] The microwave treatment time of Example 1 was adjusted to 30 seconds, the dry heat treatment time was adjusted to 10 minutes, and the others were kept the same as in Example 1. A combined vacuum treatment group 2 (L2) was obtained.

[0096] Example 4

[0097] A ternary coupled rice bran fatty acid oxidation inhibition and control method comprises the following steps:

[0098] The microwave power in Example 1 was adjusted to 400 W, the dry heat temperature was adjusted to 120° C., and the others were kept the same as in Example 1. A combined vacuum treatment group 3 (L3) was obtained.

[0099] Comparative Example 1

[0100] A ternary coupled rice bran fatty acid oxidation inhibition and control method comprises the following steps:

[0101] The dry heat treatment operation in Example 1 was omitted, and the other procedures were the same as in Example 1 to obtain a single vacuum microwave treatment group (WD).

[0102] Comparative Example 2

[0103] A ternary coupled rice bran fatty acid oxidation inhibition and control method comprises the following steps:

[0104] The vacuum pump in Example 1 was omitted to maintain the low pressure environment in the chamber, and the circulating fan was used to introduce nitrogen. Other operations were consistent with Example 1 to obtain a single non-vacuum microwave treatment group (HD).

[0105] Test results show

[0106] The lipase activity, lipoxygenase activity, fatty acid value, carbonyl value, total bacterial count, fatty acid composition and content of the single / combined treated rice bran obtained in Examples 2 to 4 and Comparative Examples 1 to 2 were measured. The test results are as follows:

[0107] See also Figure 1 , Figure 2 The changes of rice bran lipase and lipoxygenase activities under single / combination treatments are shown in Figure 1 , Figure 2 As shown. The fat in rice bran will generate free fatty acids under the action of lipase, and the generated free fatty acids will generate peroxides under the action of oxidase. In addition, the unsaturated fatty acids contained in rice bran itself will also undergo oxidation reaction under the action of lipoxygenase to generate peroxides. It can be seen that enzymes play a very important role in the fatty acid oxidation process. Therefore, the effect of different treatment methods on the oxidation of rice bran fatty acids can be evaluated by measuring the enzyme activity in rice bran after different treatments. Figure 1 It can be seen that after 30 days of storage, the lipase activity in the HD treatment group was the highest, at 53.37%, and the lipase activity in the L1 treatment group was the lowest, at 18.48%. At the same time, the lipase activity of the rice bran in the combined vacuum treatment group was significantly (P<0.05) lower than that in the single treatment group. Figure 2 It can be seen that after 30 days of storage, the lipoxygenase activity in the HD treatment group was the highest, at 53.06%, while the lipoxygenase activity in the L1 treatment group was the lowest, at 15.28%. The lipoxygenase activity in the combined vacuum treatment group was significantly (p<0.05) lower than that in the single vacuum treatment group, which was consistent with the results of lipase activity.

[0108] In summary, the combined treatment group was significantly better than the single treatment group in the inhibitory effect on the activity of rice bran lipase and lipoxygenase. This was mainly due to the fact that the rice bran in the single treatment group was not heated uniformly by microwave treatment and had a slow thermal conductivity due to the lack of a vacuum environment, resulting in an unsatisfactory enzyme inactivation effect. Therefore, the enzyme activity was significantly higher (p<0.05) than that in the combined treatment group after storage for 30 days. The combined treatment group had the characteristics of dry heat treatment and vacuum environment at the same time, which resulted in a more thorough inhibition of the activity of rice bran lipase and lipoxygenase. Therefore, the enzyme activity remained low after storage for 30 days.

[0109] See also Figure 3The changes of rice bran fatty acid values ​​under single / combination treatments are shown in Figure 3 As shown. The fat in rice bran will be hydrolyzed by lipase to form free fatty acids, which will then be oxidized to form peroxides. Therefore, measuring the fatty acid value of rice bran can determine the degree of fatty acid oxidation. Figure 3 It can be seen that during the storage period, the fatty acid values ​​of the single treatment group and the combined treatment group showed an upward trend. After 30 days, the fatty acid values ​​of HD and WD were 108.59 mg / 100g and 85.39 mg / 100g, respectively, which were about 7 times and 5.6 times of the 0th day, respectively, and significantly higher (p<0.05) than the combined treatment group. This shows that the combined vacuum treatment group played a more positive role in slowing down the increase in the fatty acid value of rice bran.

[0110] See also Figure 4 The changes of carbonyl values ​​of rice bran under single / combination treatments are shown in Figure 4 The carbonyl value reflects the oxidation and rancidity of fatty acids in rice bran during the late storage period. Figure 4 It can be seen that HD and WD increased slowly from the 0th day to the 20th day, and then increased rapidly from the 25th day, with HD increasing from 55.64mmol / kg to 96.49mmol / kg and WD increasing from 51.29mmol / kg to 90.40mmol / kg. After 30 days of storage, the carbonyl values ​​of the combined treatment group were significantly (p<0.05) lower than those of the single treatment group, indicating that the combined vacuum treatment group had a better inhibitory effect on the oxidation of rice bran fatty acids.

[0111] See also Figure 5 The changes in the total number of colonies under single / combination treatments are shown in Figure 5 As shown. The enzymes for fatty acid oxidation in rice bran are not only found in rice bran, but also in microorganisms, and microorganisms are also one of the important sources of key enzymes for fatty acid oxidation. Figure 5 It can be seen that after 30 days of storage, the total number of colonies in WD and HD reached 17921CFU / g and 15780CFU / g, respectively, while the total number of colonies in L1, L2, and L3 was only 5264CFU / g, 6012CFU / g, and 8095CFU / g, respectively, which were 70%, 67%, 66.4%, 62%, 54.8%, and 48.7% lower than WD and HD, respectively. This is mainly because the combined treatment is more evenly heated than the single treatment, the heat source has stronger penetration, and the anaerobic conditions of the vacuum environment are not conducive to the sound field of microorganisms, so it has a better effect on inhibiting the growth of microorganisms. The stronger the inhibition of microbial growth, the better the inhibitory effect on the oxidation of rice bran fatty acids.

[0112] Please refer to Table 1 and Table 2 for the changes in fatty acid composition and content under single / combined treatment. Table 1 and Table 2 show that the fatty acid components in rice bran oil are mainly palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, and arachidic acid, accounting for more than 90% of the total fatty acid content. After single / combined treatment, there was no significant change (p>0.05) in either saturated fatty acid content or unsaturated fatty acid content. This also indirectly shows that neither vacuum single nor vacuum combined treatment will affect the content of saturated fatty acids and unsaturated fatty acids in rice bran after treatment. Table 2 shows that after 30 days of storage, the total saturated fatty acid content of rice bran in the single / combined treatment group increased, while the polyunsaturated fatty acid content decreased. In the process of oil oxidation, the fatty acid content usually shows a decrease in polyunsaturated fatty acid content and an increase in saturated fatty acid content, which indicates that the more severe the oxidation of oil, the greater the decrease in polyunsaturated fatty acids and the greater the increase in saturated fatty acids. Compared with the 0th day, the content of polyunsaturated fatty acids in the HD treatment group decreased by 5.61% and the content of saturated fatty acids increased by 2.97%; the content of polyunsaturated fatty acids in the WD treatment group decreased by 4.1% and increased by 2.06%; the content of polyunsaturated fatty acids in the L1 treatment group decreased by 0.54% and increased by 0.57%; the content of polyunsaturated fatty acids in the L2 treatment group decreased by 0.96% and increased by 0.82%; the content of polyunsaturated fatty acids in the L3 treatment group decreased by 1.28% and increased by 0.95%. The decrease in the content of polyunsaturated fatty acids and the increase in the content of saturated fatty acids in the single treatment group were significantly higher than those in the combined treatment group. This shows that the combined treatment has a better inhibitory effect on the oxidation of rice bran fatty acids. This is mainly because the combined treatment group has a better passivation effect on lipase and fatty acid oxidase in rice bran than the single treatment. Without the catalytic effect of these enzymes, the oxidation rate of fatty acids in rice bran also slows down, so the decrease or increase in content is also reduced.

[0113] Table 1 Effects of single / combined treatments on the composition and content of fatty acids in rice bran (0day)

[0114]

[0115]

[0116] Example 5

[0117] A ternary coupled rice bran fatty acid oxidation inhibition and control method comprises the following steps:

[0118] The rice bran to be processed is placed on the conveyor belt, the low pressure environment is set to 0pa, the circulating fan speed is set to 1000rmp, the gas is selected to be nitrogen, the flow rate is selected to be 200mL / min, the microwave power is set to 0.6kW, the wavelength is 1m, the time is 1min, the dry heat temperature is set to 130℃, the time is 5min, the heat conductive element is set to 8 groups, and then the instrument is started to complete the processing. The vacuum treatment group 1 (Z1) is obtained.

[0119] Example 6

[0120] A ternary coupled rice bran fatty acid oxidation inhibition and control method comprises the following steps:

[0121] Example 5 was adjusted, the low pressure environment was 5 Pa, the microwave treatment time was 30 s, the dry heat treatment time was 8 min, and the others were the same as in Example 5. A vacuum treatment group 2 (Z2) was obtained.

[0122] Comparative Example 3

[0123] A ternary coupled rice bran fatty acid oxidation inhibition and control method comprises the following steps:

[0124] The operation of the vacuum pump to maintain the low pressure inside the chamber and the operation of the circulating fan to introduce nitrogen in Example 5 were omitted, and the other operations were consistent with Example 5 to obtain a non-vacuum treatment group (ZK).

[0125] Test results show

[0126] The peroxide value, malondialdehyde content, and fatty acid composition and content of the vacuum / non-vacuum treated rice bran obtained in Examples 5 to 6 and Comparative Example 3 were measured. The test results are as follows:

[0127] See also Figure 6 As shown in Figure 2, the changes in the peroxide value of rice bran under vacuum / non-vacuum treatment are as follows: Figure 6 As shown. Figure 6 It can be seen that on the 0th day of storage, the peroxide value of rice bran in the ZK group was 2.76mmol / kg, while that in Z1 and Z2 was 1.938mmol / kg and 1.965mmol / kg, respectively. The peroxide value of the ZK group was significantly higher (p<0.05) than that of the ZI and Z2 groups. This is mainly because the ZK group did not undergo vacuum treatment. Therefore, during the microwave treatment and dry heat treatment, the fatty acids in the rice bran would undergo oxidation reactions with oxygen under heating conditions to generate peroxides, which led to a significant increase in the peroxide value of the non-vacuum group after the heating. Due to the early vacuum treatment in the vacuum group, there was no oxygen during the heating process, and the fatty acids in the rice bran could not undergo oxidation reactions under heating conditions, thus avoiding the premature oxidation of fatty acids in the rice bran due to heating. This shows that vacuum treatment has a good effect in preventing the premature oxidation of fatty acids in rice bran caused by heating.

[0128] See also Figure 7 As shown in Figure 2, the changes of MDA in rice bran under vacuum / non-vacuum treatment are as follows: Figure 7 As shown. Figure 7It can be seen that the MDA content in the ZK group was significantly higher (p<0.05) than that in the Z1 and Z2 groups during the entire storage day 0. This is because the fatty acids in the ZK group underwent an oxidation reaction with oxygen during the heating process due to the presence of oxygen, generating excessive peroxides, which would further decompose into ketones, aldehydes and other substances. Therefore, the MDA content was positively correlated with the peroxide value. When the peroxide value was higher, the MDA content was higher. This also proves that it is necessary to perform vacuum treatment before heating in order to prevent the fatty acids in the rice bran from reacting with oxygen during the heating process and causing the loss of fatty acids due to heating. At the same time, after 30 days of storage, the MDA content in the vacuum group was also significantly lower (p<0.05) than that in the non-vacuum treatment group, which also shows that vacuum treatment played a positive role in slowing down the increase in the MDA content in rice bran.

[0129] Please refer to Table 3, the changes in fatty acid composition and content under vacuum / non-vacuum treatment are shown in Table 3. As can be seen from Table 3: after treatment, the total saturated fatty acid content and monounsaturated fatty acid content of the ZK group did not change significantly (p>0.05) compared with the Z1 and Z2 groups, while the polyunsaturated fatty acid content decreased significantly (p<0.05) compared with the Z1 and Z2 groups. This is mainly because saturated fatty acids and monounsaturated fatty acids are single-bond structures, which are relatively stable under heating and are not easy to break bonds and react. Polyunsaturated fatty acids are double-bond structures, which are unstable and easily break double bonds under heating conditions. The fatty acids in rice bran are oxidized prematurely due to heating under aerobic conditions. These fatty acids are usually unstable unsaturated fatty acids. Therefore, this result shows that vacuum treatment can effectively reduce the reduction in the amount of unsaturated fatty acids and effectively avoid the oxidation of fatty acids caused by heating.

[0130] Table 3 Effect of vacuum / non-vacuum treatment on the composition and content of fatty acids in rice bran

[0131]

[0132]

[0133] Example 7

[0134] A ternary coupled rice bran fatty acid oxidation inhibition and control method comprises the following steps:

[0135] The rice bran to be processed is placed on the conveyor belt, the low pressure environment is set to 0pa, the circulating fan speed is set to 1000rmp, the gas is selected to be nitrogen, the flow rate is selected to be 200mL / min, the microwave power is set to 0.6kW, the wavelength is 1m, the time is 1min, the dry heat temperature is set to 130℃, the time is 5min, the heat conductive element is set to 8 groups, and then the instrument is started to complete the processing. The vacuum combined processing group 1 (F1) is obtained.

[0136] Comparative Example 4

[0137] A ternary coupled rice bran fatty acid oxidation inhibition and control method comprises the following steps:

[0138] The dry heat treatment operation in Example 6 was omitted, and the other procedures were kept consistent with Example 6 to obtain a vacuum microwave treatment group F2 (F2).

[0139] Comparative Example 5

[0140] A ternary coupled rice bran fatty acid oxidation inhibition and control method comprises the following steps:

[0141] The operation of the vacuum pump to maintain the low pressure inside the chamber and the operation of the circulating fan to introduce nitrogen in Example 6 were omitted, and the other operations were consistent with Example 6 to obtain a non-vacuum treatment group (ZF).

[0142] Test results show

[0143] The free phenol / bound phenol content of the differently treated rice bran obtained in Example 7 and Comparative Examples 5-6 was measured. The test results are as follows:

[0144] See also Fig. 9 The changes in the contents of free phenol and bound phenol in rice bran under different treatments are shown in the figure. Fig. 9 It can be seen that the free phenol and bound phenol contents in the F1 treatment group were significantly higher than those in the F2 and ZF treatment groups. This is mainly because dry heat treatment promotes the molecular rearrangement of the compound and enhances its intramolecular stability, such as forming more covalent bonds or cross-linked structures to effectively retain the activity of phenolic components. The vacuum environment also reduces the frequency of intermolecular collisions and the possibility of thermal decomposition of phenolic substances. The low oxygen partial pressure under vacuum also helps to maintain the activity of natural antioxidants and indirectly and effectively retains the active ingredients of phenolic substances. This shows that the operation of vacuum microwave combined with dry heat treatment has a significant effect on maintaining the active ingredients of phenolic substances in rice bran.

[0145] Although the embodiments of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments.

Claims

1. A ternary coupled rice bran fatty acid oxidation inhibition and control method, characterized in that: The steps include: S1, sieving fresh rice bran through a funnel, sieving, washing the fresh rice bran with clean water, filtering, and drying; S2, mixing the dried rice bran with 5%-10% of mushroom residues, and adding a natural antioxidant, wherein the amount of the natural antioxidant added is 0.01%-0.1% of the mass of the rice bran, to obtain a rice bran mixture; S3, bagging the rice bran mixture, introducing high-purity nitrogen into the bag, establishing a preliminary inert gas environment, reducing the pressure in the bag to ≤5Pa, and forming a high vacuum environment; S4, subjecting the rice bran mixture processed in step S3 to microwave-coupled dry heat treatment.

2. The ternary coupled rice bran fatty acid oxidation inhibition and control method according to claim 1, wherein: Fresh rice bran processed within 5 hours is selected as the raw material, and the raw material is sieved through a 40-mesh sieve funnel.

3. The ternary coupled rice bran fatty acid oxidation inhibition and control method according to claim 2, wherein: The natural antioxidant is ferulic acid.

4. The device of the ternary coupled rice bran fatty acid oxidation inhibition and control method according to any one of claims 1 to 3, characterized in that: It includes a vacuum cavity, a funnel, a multi-layer transport conveyor belt, a temperature sensor, a circulating fan, a vacuum pump, a microwave generating module, a dry heat treatment module and a control system; the vacuum cavity is rectangular and arranged in the horizontal direction, a sealing cover is arranged at the top center of the vacuum cavity, the top of the sealing cover is connected to the funnel, the opening of the funnel is connected to the multi-layer transport conveyor belt, and a temperature sensor is also arranged on the top of the vacuum cavity; an air inlet and an air outlet are respectively arranged on the two side walls of the vacuum cavity, the air inlet is connected to the air outlet end of the circulating fan, and the air outlet is connected to the air inlet end of the circulating fan to form a closed-loop air path; a vacuum interface is also opened on one side wall of the vacuum cavity, and the vacuum interface is connected to the vacuum pump through a pipeline; a microwave generating module and a control system are respectively arranged on the outer wall of the vacuum cavity, and a dry heat treatment module is arranged at the bottom of the vacuum cavity.

5. The device of the ternary coupled rice bran fatty acid oxidation inhibition and control method according to claim 4, characterized in that: It also includes a gas control module, which is arranged in series with the circulation fan and is used to adjust the circulation wind speed and introduce inert gas.

6. The device of the ternary coupled rice bran fatty acid oxidation inhibition and control method according to claim 5, characterized in that: The rotation speed of the circulating fan is 100-3000rpm.

7. The device of the ternary coupled rice bran fatty acid oxidation inhibition and control method according to claim 6, characterized in that: The flow rate of the gas in the gas control module is 10-600 mL / min.

8. The device of the ternary coupled rice bran fatty acid oxidation inhibition and control method according to claim 7, characterized in that: The dry heat module realizes heat supply by an electric heating element arranged at the bottom of the vacuum cavity, and the dry heat module is equipped with 6-18 groups of high-efficiency heat-conducting elements.

9. The device of the ternary coupled rice bran fatty acid oxidation inhibition and control method according to claim 8, characterized in that: The material of the vacuum cavity is a high-strength stainless steel lining insulation layer, and the inner layer of the vacuum cavity is 3-5 layers of composite nano thermal insulation material.

10. The device of the ternary coupled rice bran fatty acid oxidation inhibition and control method according to claim 9, characterized in that: The low pressure environment in the vacuum chamber is ≤5Pa.

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