Method for retaining fragrance of rapeseed oil

Abstract

The invention discloses a method for retaining fragrance of rapeseed oil, and belongs to the technical field of rapeseed oil processing and storage. The method comprises the following steps: firstly, selecting small-particle rapeseeds in high-altitude, long-day, strong-radiation and large-temperature-difference regions in the aroma producing step, cleaning, storing in a dark place at low temperature, heating by a seed frying machine and a microwave oven until the cross section is brown, and tempering and hot pressing to ensure that the produced rapeseed oil is rich in aroma; in the fragrance keeping step, smoke generated in the seed frying and squeezing process is collected, a fragrant concentrated solution is obtained through condensation, activated carbon adsorption and desorption and fractionation and purification, the fragrant concentrated solution is added back into the rapeseed oil, the fragrance of the rapeseed oil is improved, and the problem of volatilization and loss of fragrant substances in a traditional hot squeezing process is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of rapeseed oil processing and storage, and in particular relates to a method for retaining the aroma of rapeseed oil. Background Art

[0002] Aroma-pressed rapeseed oil is produced using a traditional hot-pressing method. During the roasting and pressing process, the rapeseed structure changes, releasing many flavor compounds into the air and impacting environmental quality. While some companies have implemented measures, these have had limited success. Flavor compounds (aroma) are constantly wasted and degraded during production, refining, bottling, storage, transportation, and sales. By the time consumers consume the oil, some of these compounds may have completely disappeared, rendering the aroma of the oil less pronounced. Summary of the Invention

[0003] In view of the problems existing in the prior art, the object of the present invention is to provide a method for retaining the aroma of rapeseed oil.

[0004] In order to solve the above problems, the present invention adopts the following technical solutions: A method for retaining the aroma of rapeseed oil comprises the following steps: S1: Aroma production step: produce aroma during rapeseed oil processing; S2: Aroma preservation step: recovering the aroma volatilized during the high-temperature processing of rapeseed oil; Among them, S1 includes the following steps: S1-1: Seed selection: Select small-grain rapeseed from areas with an altitude of more than 2,500 meters, an annual sunshine duration of more than 2,200 hours, an annual solar radiation of 130-150 kcal / cm², and a day-night temperature difference of more than 12°C. S1-2: Cleaning: Remove moldy seeds, sediment, impurities and dust from the rapeseed obtained from the seed selection in S1-1; S1-3: Rapeseed storage: Store the rapeseed after cleaning in S1-2 at low temperature and away from light; S1-4: Roasting the rapeseeds: The rapeseeds stored in S1-3 are roasted in a seed roaster. After the rapeseeds are crushed and slightly browned, they are transferred to a microwave oven for heating and baking. When the diameter cross section of the rapeseeds turns browned, the seed roasting is completed. S1-5: Conditioning: Add the rapeseed fried in S1-4 into the conditioning machine and spray with boiling water for conditioning; S1-6: Pressing: The rapeseed obtained in S1-5 is hot-pressed through an oil press to obtain rapeseed oil; S2 includes the following steps: S2-1: Smoke collection: Collect the smoke generated during the seed frying process in S1-4 and the pressing process in S1-6; S2-2: Condensation and preliminary separation: The flue gas collected in S2-1 is condensed and cooled to below 100°C to obtain a liquid oil-water mixture and residual gas; S2-3: Adsorption and desorption: The remaining gas obtained in S2-2 is passed through an activated carbon adsorption bed, where the aroma molecules are adsorbed and water vapor is discharged. The gas is then heated to above 150°C to desorb and concentrate the aroma. S2-4: Fractional distillation and purification: The concentrated aroma obtained in S2-3 is passed through a fractionating tower to separate the aroma concentrate of different component compounds according to their boiling point differences; S2-5: Adding back the flavor concentrate: adding the flavor concentrate obtained in S2-4 back into the rapeseed oil obtained in S1-6 to obtain the aroma-preserved rapeseed oil.

[0005] Preferably, the method of the present invention further comprises S3: a fragrance preservation step: preserving the fragrance during the rapeseed oil refining process; S3 includes the following steps: S3-1: Gradual filtration, cooling and storage: The rapeseed oil obtained in S2-5 is filtered through a graded filter plate to remove meal residues and impurities, and then placed in a sealed stainless steel temporary storage tank for cooling and nitrogen filling to store the oil until the oil temperature drops to 30°C. S3-2: Low-temperature coarse filtration: Filter the rapeseed oil temporarily stored in the S3-1 temporary storage tank through a frame filter paper to further remove impurities. The filtration process is carried out in a closed low-temperature state, and the temperature is maintained between 23°C ± 3°C; S3-3: Low-temperature fine filtration: The rapeseed oil filtered in S3-2 is sent to the winterization tank for winterization. The winterization requirements are: temperature -5 to -10°C, time 48 hours, stirring speed 15 circles / minute, and the winterized oil is then finely filtered using a 100-layer rice paper filter. The filtration process is carried out in a closed and low-temperature state, and the temperature is maintained between 20°C±3°C.

[0006] Preferably, the method of the present invention further comprises S4: a fragrance retention step: retaining the fragrance during the storage and packaging process of the rapeseed oil; S4 includes the following steps: S4-1: Constant temperature and nitrogen-filled storage: The rapeseed oil filtered in S3-3 is placed in a sealed stainless steel temporary storage tank and stored in a constant temperature and nitrogen-filled tank; S4-2: Repackaging in fragrance bottles: Repack the rapeseed oil temporarily stored in the S4-1 temporary storage tank into fragrance bottles.

[0007] Preferably, in S2-1, smoke pipes are provided on the seed roasting machine and the oil press to collect smoke generated during the seed roasting process and the oil press process; In S2-2, the end of the flue gas pipe is connected to a steam-water separator, which condenses the collected flue gas to below 100°C to obtain a liquid oil-water mixture and residual gas; In S2-3, the gas outlet of the steam-water separator is connected to the adsorption-desorption box through a pipeline. The adsorption-desorption box is provided with a plurality of activated carbon adsorption beds and a heating device. The aroma molecules in the residual gas are adsorbed by the activated carbon adsorption beds, and then the aroma molecules in the activated carbon adsorption beds are desorbed by the heating device. In S2-4, a plurality of distillation towers are connected in series at the end of the adsorption-desorption box through a pipeline according to the boiling point from high to low. A collecting tank is set at the bottom of each distillation tower. The flavor concentrates of different component compounds are separated according to the boiling point difference through the multiple distillation towers, and the flavor concentrates are recovered through the collecting tanks.

[0008] Preferably, in S1-2, moldy grains in the rapeseed are removed by a color sorter and an ultraviolet irradiator, and silt, impurities and dust in the rapeseed are removed by a grading vibrating screen, a specific gravity stone remover and a magnetic separator; In S1-3, rapeseed is stored in low temperature and dark environment by vertical silos; In S1-5, rapeseed is added to the conditioner, stirred for 2 minutes, sprayed with 1% boiling water, and stirred at a speed of 30 revolutions / minute for 5 minutes; In S1-6, rapeseed is hot pressed by a 95-type screw oil press.

[0009] Preferably, in S1-3, the vertical silo is a cylindrical galvanized steel tank with a conical funnel-shaped bottom. A vibrator is installed inside the cone bottom of the vertical silo. A type O main air duct is laid at the bottom of the vertical silo and connected to a centrifugal fan. Branch air ducts extend to various areas in the silo. Vertical ventilation pipes are set every 0.8-1.5 meters and a height of 2.5-4.0 meters. Holes are opened in the pipe wall to promote uniform air supply. Induction thermometers and hygrometers are installed at different heights of the vertical silo to monitor data in real time and transmit them to the control system. When the temperature in the silo is higher than 30°C and the relative humidity is higher than 65%, centrifugal fans are used for ventilation to cool and dehumidify. Ventilation is avoided during high temperature periods and rainy seasons, and is carried out between 7 and 9 am or 5 and 8 pm. An axial flow fan is configured on the top of the silo to cooperate with a centrifugal fan and a dehumidifier to operate in conjunction to cope with extreme high humidity environments. In high temperature seasons, the centrifugal fan air supply temperature is reduced by cooling water heat exchange, and the grain temperature is controlled below 20°C to inhibit respiration and mold growth.

[0010] Preferably, in S4-2, the fragrance bottle is a vacuum double-layer bottle body, with a high borosilicate glass inner liner and an outer layer of explosion-proof glass. The middle is evacuated to a vacuum degree of ≤0.1Pa, and a metal sealing ring is used to achieve physical isolation; a nano-silver reflective layer is plated between the double walls, with a reflectivity of ≥95%, which blocks ultraviolet rays and infrared rays; a molecular sieve adsorption layer with a pore size of 3Å is set at the bottom of the bottle to absorb residual oxygen; a built-in neodymium iron boron magnetic ring controls a 316 stainless steel ball valve, and the magnetic force is released when the tilt is greater than 45°, and the ball valve opens by gravity, with an opening diameter of 4mm, and is equipped with a food-grade fluororubber secondary sealing ring. The leakage rate after closing is less than 0.01Pa·m³ / s, the bottle shoulder is filled with octadecanoic acid phase change material, and a graphene thermal conductive film is used to achieve uniform temperature, the bottle cap has a built-in pressure-triggered nitrogen capsule, which automatically replenishes nitrogen after opening the cap, a 120° staggered texture with a depth of 0.3mm is etched on the surface of the bottle body, and a spiral guide groove is set to match the fish-mouth type oil outlet.

[0011] Beneficial effects of the present invention: Compared with the prior art, the advantages of the present invention are: The present invention achieves aroma retention through an aroma generating step and an aroma preserving step: first, in the aroma generating step, small-grain rapeseeds are selected from areas with high altitudes, long sunshine, strong radiation, and large temperature differences, and after being cleaned and stored at low temperature and away from light, they are heated until the cross section is browned by a seed roasting machine and a microwave oven, and then tempered and hot-pressed to ensure that the produced rapeseed oil has a strong aroma; in the aroma preserving step, smoke generated during the seed roasting and pressing processes is collected, and a flavor concentrate is obtained through condensation, activated carbon adsorption and desorption, and fractional distillation purification, which is then added back into the rapeseed oil to enhance the aroma of the rapeseed oil, thereby solving the problem of volatilization and loss of aroma substances in the traditional hot pressing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the steps of the present invention; Figure 2 This is a schematic diagram of the structure of the fragrance preservation step of the present invention; Figure 3 It is a structural schematic diagram of the vertical silo of the present invention; Figure 4 It is a structural schematic diagram of the fragrance bottle of the present invention. DETAILED DESCRIPTION

[0013] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0014] like Figure 1As shown, the present invention provides a technical solution: a method for retaining the aroma of rapeseed oil, comprising the following steps: S1: Aroma production step: produce aroma during rapeseed oil processing; S1 includes the following steps: S1-1: Seed selection: Select small-grain rapeseed from areas with an altitude of more than 2,500 meters, an annual sunshine duration of more than 2,200 hours, an annual solar radiation of 130-150 kcal / cm², and a day-night temperature difference of more than 12°C. Specifically, the above-mentioned rapeseed is selected from the small-grain rapeseed (northern small-grain) from the Qinghai Plateau, which has sufficient sunshine (strong ultraviolet rays), fertile land (chernozem soil), and snow water irrigation, far away from industrial pollution. This rapeseed has high nutritional value (essential fatty acids 1:1), strong aroma (more than 100 flavor substances, as shown in the table below), pure flavor, strong antioxidant properties, etc., which can significantly enhance the aroma.

[0015] Comparison of aroma substances in different rapeseeds: At the same time, the plateau small-grain rapeseed was tested and analyzed with more than 40 selected rapeseed varieties, and it was found that the plateau small-grain rapeseed had higher contents of erucic acid and glucosinolates, with erucic acid content ≥20% and glucosinolate content ≥100μmol / g. After repeated tests and verifications, it was found that the source of rapeseed oil aroma was mainly determined by the level of erucic acid and glucosinolates in the rapeseed. Therefore, the plateau small-grain rapeseed was selected.

[0016] Table of the relationship between erucic acid, glucosinolate content and aroma of rapeseed in different regions (main producing areas): S1-2: Cleaning: Remove moldy grains, sediment, impurities and dust from the rapeseed obtained from the seed selection in S1-1 to reduce oil adsorption loss. The quality indicators of the rapeseed after cleaning must meet the requirements (immature grains ≤6%, heat-damaged grains ≤1%, sprouted grains ≤2%, moldy grains ≤2%, impurities ≤1%, moisture ≤8%, and normal color and smell). Traditional cleaning only removes impurities (organic impurities and inorganic impurities) in rapeseed, but the key factor that really affects the aroma of rapeseed oil is the moldy grains of rapeseed. If rapeseed containing moldy grains is used to press oil, odors (such as moldy and rancid) may remain in the oil, the color deepens, and the acid value (reflecting the degree of rancidity of the oil) and peroxide value increase, affecting the flavor and shelf life of the edible oil. Removing moldy grains can make the squeezed oil clearer and taste better; S1-3: Rapeseed Storage: After S1-2 cleaning, rapeseed should be stored at low temperature and away from light. Cleaning is a basic condition for the safe storage of rapeseed, but the key condition is that rapeseed is a small-grain crop and must be stored in a cool and dry place (storage moisture ≤ 8%). S1-4: frying seeds: frying seeds requires controlling the temperature. The present invention adopts a method combining a rotary stirring seed frying machine and a microwave. First, the rapeseed stored in S1-3 is frying the seeds in a 100-115KG rotary stirring seed frying machine. The rapeseed is externally heated. The temperature of the seed frying pan is set at 159°C and the frying time is 30 minutes. After the rapeseed is crushed and slightly browned, it is transferred to a microwave oven for heating and baking. The microwave oven is set for 10 minutes and the microwave frequency is 2450MHz. When the diameter section of the rapeseed appears browned, the seed frying is completed and the rapeseed moisture content is ≤1.5%. Traditional seed roasting uses a rotating iron pan or a flat-bottomed stirring pan, heated by wood, charcoal, natural gas, or electricity. Temperature control is not strictly required, as long as there is a hint of fragrance and a high oil yield. However, due to poorly selected seed roasting equipment and uncontrolled roasting process and results, the resulting rapeseed is not the most fragrant. After long-term research and testing of more than a dozen seed roasting methods, a comparative analysis ultimately led to the selection of a microwave-assisted and traditional roasting method, as this method produces the most fragrant rapeseed. A 100-115 kg rotary stirring seed roaster was selected. This not only stirs the seeds evenly but also effectively heats the rapeseed surface. Microwave equipment is a newly developed heating method that uses electromagnetic waves to heat the rapeseed from the inside out, providing excellent penetration and stable, uniform heating.

[0017] Comparison table of several seed frying methods: S1-5: Tempering: The roasted rapeseed seeds from S1-4 are added to a tempering machine and sprayed with boiling water for tempering. Specifically, the roasted rapeseed seeds are added to the tempering machine, stirred for 2 minutes, and then sprayed with boiling water (1% spray rate) while still hot. Stirring is then uniform (stirring at 30 revolutions / minute). Tempering is then continued for 5 minutes to raise the moisture content of the rapeseed seeds to 2-3%. This promotes the degradation of glucosinolates and the production of volatile flavor compounds, such as glucosinolate degradation products (isothiocyanates) and oxidized volatiles (aldehydes and ketones), creating a rich aroma. Traditional methods of roasting rapeseed seeds may or may not add water, add cold water, or add hot water, or stir or not stir, resulting in irregular tempering processes. The present invention, through testing and verification, precisely adds water, adds boiling water, and uniformly stirs, distributing moisture and heat. The tempered rapeseed seeds exhibit excellent elasticity and plasticity, meeting pressing requirements.

[0018] Comparison of different tempering conditions after frying seeds: S1-6: Pressing: The rapeseed obtained in S1-5 is hot-pressed through an oil press to produce rapeseed oil. Specifically, the present invention utilizes a 95-type screw oil press. The pressing process disrupts the rapeseed's molecular structure, fully releasing its aromatic components through high-pressure grinding and squeezing. The press chamber design enhances mechanical friction, promoting the extraction of aromatic compounds.

[0019] Comparison of different oil presses and aroma of squeezed oil: During pressing, the temperature entering the press should not be lower than 100℃. At the same time, the feed amount is controlled according to the oil output and the color and thickness of the cake. The pressing chamber pressure and the cake thickness (1.25-2.5 mm) are adjusted to ensure that the oil is fully released while avoiding burning. The residual oil in the dry cake is controlled between 6-7%, balancing the oil output rate and flavor retention.

[0020] The aroma components of rapeseed oil are mainly volatile organic compounds (VOCs), such as aldehydes, alcohols, nitrogen-containing compounds (nitriles, pyrazines, etc.) and sulfur-containing compounds, with boiling points mostly concentrated between 120-160°C. Therefore, the aroma components are easily volatilized by high temperatures during the seed roasting and pressing process. To solve this problem, the present invention uses S2: aroma preservation step to recover the aroma volatilized during the high-temperature processing of rapeseed oil; Among them, S2 includes the following steps: S2-1: Smoke collection: Collect the smoke generated during the seed frying process in S1-4 and the pressing process in S1-6; S2-2: Condensation and preliminary separation: The flue gas collected in S2-1 is condensed and cooled to below 100°C to obtain a liquid oil-water mixture and residual gas; S2-3: Adsorption and desorption: The remaining gas obtained in S2-2 is passed through an activated carbon adsorption bed, where the aroma molecules are adsorbed and water vapor is discharged. The gas is then heated to above 150°C to desorb and concentrate the aroma. S2-4: Fractional distillation and purification: The concentrated aroma obtained in S2-3 is passed through a fractionating tower to separate the aroma concentrate of different component compounds according to their boiling points (e.g., target compounds at 120–160°C); S2-5: Adding back the flavor concentrate: adding the flavor concentrate obtained in S2-4 back into the rapeseed oil obtained in S1-6 to obtain the aroma-preserved rapeseed oil.

[0021] Comparison of aroma substances in rapeseed oil before and after aroma recovery: The present invention achieves aroma retention through an aroma generating step and an aroma preserving step: first, in the aroma generating step, small-grain rapeseeds are selected from areas with high altitudes, long sunshine, strong radiation, and large temperature differences, and after being cleaned and stored at low temperature and away from light, they are heated until the cross section is browned by a seed roasting machine and a microwave oven, and then tempered and hot-pressed to ensure that the produced rapeseed oil has a strong aroma; in the aroma preserving step, smoke generated during the seed roasting and pressing processes is collected, and a flavor concentrate is obtained through condensation, activated carbon adsorption and desorption, and fractional distillation purification, which is then added back into the rapeseed oil to enhance the aroma of the rapeseed oil, thereby solving the problem of volatilization and loss of aroma substances in the traditional hot pressing process.

[0022] Furthermore, the method of the present invention further comprises S3: a fragrance preservation step: preserving the fragrance during the rapeseed oil refining process; S3 includes the following steps: S3-1: Gradual filtration, cooling and storage: The rapeseed oil obtained in S2-5 is filtered through a graded filter plate to remove meal residues and impurities, and then placed in a sealed stainless steel temporary storage tank for cooling and nitrogen filling to store the oil until the oil temperature drops to 30°C. S3-2: Low-temperature coarse filtration: Filter the rapeseed oil temporarily stored in the S3-1 temporary storage tank through a frame filter paper to further remove impurities. The filtration process is carried out in a closed low-temperature state, and the temperature is maintained between 23°C ± 3°C; S3-3: Low-temperature fine filtration: The rapeseed oil filtered in S3-2 is sent to the winterization tank for winterization. The winterization requirements are: temperature -5 to -10°C, time 48 hours, stirring speed 15 circles / minute. The winterized oil is then finely filtered using a 100-layer rice paper filter. The filtration process is carried out in a closed and low-temperature state, and the temperature is maintained between 20°C±3°C.

[0023] After sampling and testing the stored oil, it was found to have a strong aroma and clear color, and the quality indicators tested were in line with GB / T1536 (test report attached).

[0024] Comparison before and after storing incense: Inspection report: Furthermore, the method of the present invention further comprises S4: a fragrance retention step: retaining the fragrance during the storage and packaging process of the rapeseed oil; S4 includes the following steps: S4-1: Constant temperature and nitrogen storage: The rapeseed oil filtered in S3-3 is placed in a sealed stainless steel temporary storage tank and stored in a constant temperature and nitrogen-filled tank; S4-2: Fragrance bottle packaging: The rapeseed oil temporarily stored in the S4-1 temporary storage tank is packaged in fragrance bottles.

[0025] Comparison of the fragrance before and after storage of the fragrance bottle for 18 months: In summary, the present invention adopts a processing method that can both produce and preserve fragrance during the squeezing process, and preserve and retain fragrance during the refining, packaging, storage and transportation processes, to ensure that the food is full of fragrance, delicious and fresh when consumed by consumers.

[0026] Specifically, in S2-1, if Figure 2 As shown, smoke pipes are set on the seed frying machine and the oil press to collect the smoke generated during the seed frying process and the pressing process; In S2-2, the end of the flue gas pipe is connected to a steam-water separator, which condenses the collected flue gas to below 100°C to obtain a liquid oil-water mixture and residual gas; In S2-3, the gas outlet of the steam-water separator is connected to the adsorption-desorption box through a pipeline. The adsorption-desorption box is provided with a plurality of activated carbon adsorption beds and a heating device. The aroma molecules in the residual gas are adsorbed by the activated carbon adsorption beds, and then the aroma molecules in the activated carbon adsorption beds are desorbed by the heating device. In S2-4, a plurality of distillation towers are connected in series at the end of the adsorption-desorption box through a pipeline according to the boiling point from high to low. A collecting tank is set at the bottom of each distillation tower. The flavor concentrates of different component compounds are separated according to the boiling point difference through the multiple distillation towers, and the flavor concentrates are recovered through the collecting tanks.

[0027] Specifically, in S1-2, moldy kernels are removed from rapeseed using a color sorter and UV irradiation system. Color sorting for moldy rapeseed consists of two stages. In the identification stage, a high-resolution CCD camera or micron-level sensor illuminates the material from multiple angles, capturing characteristics such as color and shape. Moldy kernels can be identified by the algorithm due to their dark color or surface spots. In the sorting stage, after defects are identified, a high-speed magnetic levitation spray valve (with a response time in the millisecond range) blows the moldy kernels out of the material flow, retaining qualified kernels. The color sorting equipment removes moldy kernels, achieving 100% screening efficiency and zero mold content in the rapeseed. Simultaneously, the sorted rapeseed is irradiated with UV light at a wavelength of 254nm for 30 minutes to remove toxins from the rapeseed. Sediment, impurities, and dust are removed from the rapeseed using a grading vibrating screen, a gravity stone remover, and a magnetic separator.

[0028] The traditional method of storing rapeseed is to pack it in woven bags (50 kg), stack it off the ground and against the wall, and leave ventilation ducts between the stacks, or store it in bulk. This method makes rapeseed difficult to detect, easily affected by moisture and heat, and prone to caking, mold, and browning. In response to this phenomenon, the present invention stores rapeseed in vertical silos, which are not only moisture-proof, insect-proof, and light-proof, but also can timely adjust ventilation according to the set temperature requirements, so as to achieve monitoring and regulation at the same time, ensuring high safety during the storage of raw materials. The specific design scheme is as follows: In S1-3, if Figure 3As shown, the silo is a cylindrical galvanized steel tank with a conical funnel-shaped bottom, which facilitates the natural flow and discharge of rapeseed, minimizing residue. A discharge port is located at the bottom of the cone, with an adjustable valve to control flow. A vibrator is installed inside the cone to loosen the rapeseed and prevent clumping and blockage caused by excessive humidity. An O-shaped main air duct is installed at the bottom of the silo, connected to a centrifugal fan. Branch ducts extend to various areas within the silo. Vertical ventilation ducts are installed at intervals of 0.8-1.5 meters, with heights of 2.5-4.0 meters. Perforations in the duct walls promote uniform air distribution. A "top-in, bottom-out" or "bottom-in, top-out" circulation pattern is used. Temperature and humidity sensors dynamically adjust airflow direction to ensure uniform temperature and humidity within the grain pile. Induction thermometers and hygrometers are installed at different heights within the silo (surface, middle, and bottom layers) to monitor real-time data and transmit it to the control system. When the temperature in the warehouse is higher than 30℃ and the relative humidity is higher than 65%, centrifugal fans are used for ventilation to cool down and remove moisture. Ventilation should be avoided during high temperature periods and rainy seasons. It should be carried out between 7-9 am and 5-8 pm. Axial fans are installed on the top of the warehouse in conjunction with centrifugal fans and dehumidifiers to cope with extreme high humidity environments. In high temperature seasons, the air supply temperature of the centrifugal fan is reduced through cooling water heat exchange, and the grain temperature is controlled below 20℃ to inhibit respiration and mold growth.

[0029] Preferably, in S4-2, as Figure 4 As shown, the fragrance bottle is a vacuum double-layer bottle with a high borosilicate glass inner liner and an outer layer of explosion-proof glass. The middle is vacuumed with a vacuum degree of ≤0.1Pa, and a metal sealing ring is used to achieve physical isolation. A nano-silver reflective layer is plated between the double walls with a reflectivity of ≥95% to block ultraviolet rays and infrared rays. A molecular sieve adsorption layer with a pore size of 3Å is set at the bottom of the bottle to absorb residual oxygen. A built-in neodymium iron boron magnetic ring controls a 316 stainless steel ball valve. When the tilt is greater than 45°, the magnetic force is released and the ball valve opens by gravity. The opening diameter is 4mm and is equipped with a food-grade fluororubber secondary sealing ring. The leakage rate after closing is less than 0.01Pa·m³ / s. The shoulder of the bottle is filled with octadecanoic acid phase change material, and a graphene thermal conductive film is used to achieve temperature uniformity. The bottle cap has a built-in pressure-triggered nitrogen capsule, which automatically replenishes nitrogen after opening the lid. A 120° staggered texture with a depth of 0.3mm is etched on the surface of the bottle body, and a spiral guide groove is set with a fish-mouth oil outlet.

[0030] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for retaining the aroma of rapeseed oil, characterized in that, The following steps are involved: S1: Aroma production step: produce aroma during rapeseed oil processing; S2: Aroma preservation step: recovering the aroma volatilized during the high-temperature processing of rapeseed oil; Among them, S1 includes the following steps: S1-1: Seed selection: Select small-grain rapeseed from areas with an altitude of more than 2,500 meters, an annual sunshine duration of more than 2,200 hours, an annual solar radiation of 130-150 kcal / cm², and a day-night temperature difference of more than 12°C. S1-2: Cleaning: Remove moldy seeds, sediment, impurities and dust from the rapeseed obtained from the seed selection in S1-1; S1-3: Rapeseed storage: Store the rapeseed after cleaning in S1-2 at low temperature and away from light; S1-4: Roasting the rapeseeds: The rapeseeds stored in S1-3 are roasted in a seed roaster. After the rapeseeds are crushed and slightly browned, they are transferred to a microwave oven for heating and baking. When the diameter cross section of the rapeseeds turns browned, the seed roasting is completed. S1-5: Conditioning: Add the rapeseed fried in S1-4 into the conditioning machine and spray with boiling water for conditioning; S1-6: Pressing: The rapeseed obtained in S1-5 is hot-pressed through an oil press to obtain rapeseed oil; S2 includes the following steps: S2-1: Smoke collection: Collect the smoke generated during the seed frying process in S1-4 and the pressing process in S1-6; S2-2: Condensation and preliminary separation: The flue gas collected in S2-1 is condensed and cooled to below 100°C to obtain a liquid oil-water mixture and residual gas; S2-3: Adsorption and desorption: The remaining gas obtained in S2-2 is passed through an activated carbon adsorption bed, where the aroma molecules are adsorbed and water vapor is discharged. The gas is then heated to above 150°C to desorb and concentrate the aroma. S2-4: Fractional distillation and purification: The concentrated aroma obtained in S2-3 is passed through a fractionating tower to separate the aroma concentrate of different component compounds according to their boiling point differences; S2-5: Adding back the flavor concentrate: adding the flavor concentrate obtained in S2-4 back into the rapeseed oil obtained in S1-6 to obtain the aroma-preserved rapeseed oil.

2. A method for retaining the aroma of rapeseed oil according to claim 1, characterized in that, It also includes S3: aroma preservation step: preserving the aroma during the rapeseed oil refining process; S3 includes the following steps: S3-1: Gradual filtration, cooling and storage: The rapeseed oil obtained in S2-5 is filtered through a graded filter plate to remove meal residues and impurities, and then placed in a sealed stainless steel temporary storage tank for cooling and nitrogen filling to store the oil until the oil temperature drops to 30°C. S3-2: Low-temperature coarse filtration: Filter the rapeseed oil temporarily stored in the S3-1 temporary storage tank through a frame filter paper to further remove impurities. The filtration process is carried out in a closed low-temperature state, and the temperature is maintained between 23°C ± 3°C; S3-3: Low-temperature fine filtration: The rapeseed oil filtered in S3-2 is sent to the winterization tank for winterization. The winterization requirements are: temperature -5 to -10°C, time 48 hours, stirring speed 15 circles / minute, and the winterized oil is then finely filtered using a 100-layer rice paper filter. The filtration process is carried out in a closed and low-temperature state, and the temperature is maintained between 20°C±3°C.

3. A method for retaining the aroma of rapeseed oil according to claim 2, characterized in that, It also includes S4: aroma preservation step: preserving the aroma during the storage and packaging of rapeseed oil; S4 includes the following steps: S4-1: Constant temperature and nitrogen storage: The rapeseed oil filtered in S3-3 is placed in a sealed stainless steel temporary storage tank and stored in a constant temperature and nitrogen-filled tank; S4-2: Fragrance bottle packaging: The rapeseed oil temporarily stored in the S4-1 temporary storage tank is packaged in fragrance bottles.

4. A method for retaining the aroma of rapeseed oil according to claim 1, characterized in that, In S2-1, smoke pipes are provided on the seed roasting machine and the oil press to collect smoke generated during the seed roasting and pressing processes; In S2-2, the end of the flue gas pipe is connected to a steam-water separator, which condenses the collected flue gas to below 100°C to obtain a liquid oil-water mixture and residual gas; In S2-3, the gas outlet of the steam-water separator is connected to the adsorption-desorption box through a pipeline. The adsorption-desorption box is provided with a plurality of activated carbon adsorption beds and a heating device. The aroma molecules in the residual gas are adsorbed by the activated carbon adsorption beds, and then the aroma molecules in the activated carbon adsorption beds are desorbed by the heating device. In S2-4, a plurality of distillation towers are connected in series at the end of the adsorption-desorption box through a pipeline according to the boiling point from high to low. A collecting tank is set at the bottom of each distillation tower. The flavor concentrates of different component compounds are separated according to the boiling point difference through the multiple distillation towers, and the flavor concentrates are recovered through the collecting tanks.

5. A method for retaining the aroma of rapeseed oil according to claim 1, characterized in that, In S1-2, color sorters and ultraviolet irradiators are used to remove moldy kernels from rapeseed, while grading vibrating screens, gravity stone removers, and magnetic separators are used to remove sediment, impurities, and dust from the rapeseed. In S1-3, rapeseed is stored in low temperature and dark environment by vertical silos; In S1-5, rapeseed is added to the conditioner, stirred for 2 minutes, sprayed with 1% boiling water, and stirred at a speed of 30 revolutions / minute for 5 minutes; In S1-6, rapeseed is hot pressed by a 95-type screw oil press.

6. The method for retaining the aroma of rapeseed oil according to claim 5, wherein: In S1-3, the vertical silo is a cylindrical galvanized steel tank with a conical funnel-shaped bottom. A vibrator is installed inside the cone bottom of the silo. A type 0 main air duct is laid at the bottom of the silo and connected to a centrifugal fan. Branch air ducts extend to various areas in the silo. Vertical ventilation pipes are installed every 0.8-1.5 meters and at a height of 2.5-4.0 meters. Holes are opened in the pipe wall to promote uniform air supply. Induction thermometers and hygrometers are installed at different heights of the vertical silo to monitor the data in real time and transmit it to the control system. When the temperature in the silo is higher than 30°C and the relative humidity is higher than 65%, centrifugal fans are used for ventilation to cool and dehumidify. Ventilation is avoided during high temperature periods and rainy seasons and is carried out between 7 and 9 am or 5 and 8 pm. An axial flow fan is installed on the silo roof in conjunction with a centrifugal fan and a dehumidifier to operate in conjunction with the silo to cope with extreme high humidity environments. In high temperature seasons, the centrifugal fan's air supply temperature is reduced by cooling water heat exchange, and the grain temperature is controlled below 20°C, inhibiting respiration and mold growth.

7. The method for retaining the aroma of rapeseed oil according to claim 3, wherein: In S4-2, the fragrance bottle is a vacuum double-layer bottle with a high borosilicate glass inner liner and an explosion-proof glass outer layer. The middle is evacuated to a vacuum degree of ≤0.1Pa, and a metal sealing ring is used to achieve physical isolation. A nano-silver reflective layer is plated between the double walls with a reflectivity of ≥95% to block ultraviolet and infrared rays. A molecular sieve adsorption layer with a pore size of 3Å is set at the bottom of the bottle to absorb residual oxygen. A built-in neodymium iron boron magnetic ring controls a 316 stainless steel ball valve. When tilted >45°, the magnetic force is released and the ball valve opens by gravity. The opening diameter is 4mm and is equipped with a food-grade fluororubber secondary sealing ring. The leakage rate after closing is <0.01Pa·m³ / s. The shoulder of the bottle is filled with octadecanoic acid phase change material, and a graphene thermal conductive film is used to achieve temperature uniformity. The bottle cap has a built-in pressure-triggered nitrogen capsule, which automatically replenishes nitrogen after opening the cap. A 120° staggered texture with a depth of 0.3mm is etched on the surface of the bottle body, and a spiral guide groove is set with a fish-mouth-shaped oil outlet.

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