Preparation process of walnut oil

Abstract

The invention provides a preparation process of walnut oil, which comprises the following steps: pretreating a walnut kernel raw material, performing supercritical CO2 fluid isobaric switching extraction on the pretreated walnut kernel, heating the extracted walnut oil, performing three-stage molecular distillation on the walnut oil, and finally cooling the distilled walnut oil, compared with a common supercritical CO2 fluid walnut oil extraction process, the extraction yield of the walnut oil is higher, compared with a traditional oil refining process, colloid, pigment and odor in the oil are removed, inherent nutrient substances in the oil are effectively reserved, a harmful substance plasticizer component in the raw materials can be removed, edible oil is safer and more nutritional, and the production cost is reduced. And the purpose of improving the quality of the edible oil is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of walnut oil preparation, and particularly relates to a preparation process of walnut oil. Background Art

[0002] With the continuous innovation of oil extraction technology, supercritical extraction technology has stood out in the field of oil extraction. Under the physical extraction conditions of high pressure and low temperature, it can not only achieve a higher extraction rate, but also has the advantages of no chemical solvent residue in the crude oil, which has won the favor of many experts and scholars. However, if supercritical extraction technology is industrialized, and its extraction operation process is not continuous production, it will lead to reduced extraction efficiency and the cost cannot be reduced. The oil obtained by traditional process has many impurities and low purity. It needs to go through complex refining and processing processes such as dehydration, deacidification, deodorization, decolorization, deodorization and five deodorization. It takes a long time and will produce trans fatty acids and bring pollution such as heavy metals and solvent residues. Its nutrients are also lost in large quantities, which greatly reduces the quality of edible oil. The environmental pollution caused by the transition process has also become a burden on enterprises. Summary of the invention

[0003] In view of the above problems, the object of the present invention is to provide a walnut oil with a high extraction yield, which effectively retains the nutrients inherent in the oil and can also avoid the production of harmful substances in the preparation process.

[0004] The present invention is achieved through the following technical solutions: A preparation technology of walnut oil, the steps are as follows: After the walnut kernel raw material is pretreated, the pretreated walnut kernel is extracted by supercritical CO2 fluid isobaric switching, the walnut oil is heated after extraction, and then the walnut oil is molecularly distilled in three stages, and finally the distilled walnut oil is cooled.

[0005] The pretreatment of the walnut kernel raw material includes microwave drying and crushing; the microwave drying temperature is 100°C to 180°C, and the microwave drying is performed to a moisture content of 5% to 10%; the crushing particle size is 20 to 60 meshes, the walnut oil content is above 60%, and the crushing is performed using a three-roll grinder, which can minimize the occurrence of caking in walnut powder.

[0006] In order to obtain walnut oil with less impurities and high purity, which is beneficial for subsequent refining treatment, the extraction pressure in the supercritical CO2 fluid isobaric switching extraction of walnut kernels is 15-55MPa, the extraction temperature is 30-45°C, the separation pressure is 6-15MPa, the separation temperature is 50-70°C, the isobaric switching pressure is 15-55MPa, the isobaric switching time is 2-3h, and the extraction time is 4-6h.

[0007] Follow the steps below to achieve isobaric extraction of walnut kernels using supercritical CO2 fluid: Put the crushed walnut powder into the No. 1 extraction kettle, and load the material according to the bulk density of 0.4-0.5Kg / L. Adjust the equipment to the start state, set the extraction parameters to extraction pressure 15-55MPa, extraction temperature 30-45℃, separation pressure 6-15MPa, and separation temperature 50-70℃. When the temperature reaches the conditions, start to increase the pressure at a rate of 1-3MPa per minute until the pressure reaches 15-55MPa. Start circulation and record data. After the cycle starts, the extraction time is recorded, and the loading of the No. 2 extraction kettle is prepared. After the loading is completed, the spare booster pump is used to increase the pressure at a rate of 1-3 MPa per minute until the pressure reaches 15-55 MPa, the booster pump is stopped, the inlet and outlet valves of the No. 2 extraction kettle are closed, and the pressure is maintained. After the extraction time of the No. 1 extraction kettle reaches 2-4 hours, the inlet and outlet valves of the No. 2 extraction kettle are opened, and the pressure is switched to the No. 1 kettle in series with the No. 2 kettle. After the No. 1 extraction kettle continues to extract for 4-6 hours, the extraction of the No. 1 extraction kettle is completed. After 4-6 hours of extraction time, stop and release the pressure. At the same time, kettle No. 2 has completed extraction for 2-4 hours. After isobaric switching to kettle No. 1 in series with kettle No. 2, start preparing for kettle No. 3 loading, pressure increase, pressure maintenance, etc., until kettle No. 2 extraction time reaches 2-4 hours, isobaric switching to kettle No. 2 in series with kettle No. 3, kettle No. 2 continues to extract for 4-6 hours, after completing the extraction time of kettle No. 2 for 4-6 hours, stop, release the pressure, isobaric switching to kettle No. 2 in series with kettle No. 3, start preparing for kettle No. 1 loading, pressure increase, pressure maintenance, etc. The process is as follows: operate until kettle No. 3 has completed extraction for 2-4 hours, then switch to kettle No. 3 in series with kettle No. 1 at equal pressure, and kettle No. 3 continues to extract for 4-6 hours. After kettle No. 3 has completed extraction for 4-6 hours, stop and release the pressure, so as to realize continuous and uninterrupted extraction of walnut oil in this isobaric switching cyclic extraction mode. During the operation of the isobaric switching extraction mode, not only the extraction of walnut oil is realized continuously and uninterruptedly, but the pressure-maintaining operation increases the static dissolution time of supercritical CO2, thereby increasing the yield of walnut oil and improving the extraction efficiency.

[0008] The temperature of the heat-conducting oil in the heating of the extracted walnut oil is 100-120° C., the stirring speed is 10-30 r / min, and the heating time is 10-30 min. After the temperature of the walnut oil is reached, the heating and stirring are stopped, and the precipitation time is 1-6 hours. The extracted walnuts are heated before molecular distillation to increase the sedimentation time of impurities in the oil and ensure that it is consistent with the first-level distillation temperature of molecular distillation. This can not only increase the sedimentation time of impurity moisture, colloid, and protein in the oil, but also reduce the damage of the viscosity of the extracted walnut oil to the scraping film of the molecular distillation equipment, improve the film-forming effect, and then improve the removal efficiency of the distillation plasticizer in the second and third levels of molecular distillation.

[0009] The first-stage distillation process in the three-stage molecular distillation of walnut oil is as follows: the feed rate is 20-60L / h, the heat transfer oil temperature is 100-120°C, the condensation surface temperature is 0-35°C, the vacuum degree is 30-100Pa, the heavy component material pump frequency is 30-35HZ, and the light component material pump frequency is 10-20HZ; the second-stage distillation process is as follows: the heat transfer oil temperature is 120-200°C, the condensation surface temperature is 0-35°C, the vacuum degree is 10-50Pa, the heavy component material pump frequency is 30-35HZ, and the light component material pump frequency is 20-30HZ; the third-stage distillation process is as follows: the heat transfer oil temperature is 200-240°C, the condensation surface temperature is 0-35°C, the vacuum degree is 0.1-5Pa, the heavy component material pump frequency is 30-35HZ, and the light component material pump frequency is 10-20HZ.

[0010] In order to reduce the high temperature contact time of walnut oil and maximize the preservation of walnut oil nutritional ingredients and active ingredients, the distilled walnut oil is cooled: the distilled walnut oil is quickly cooled to 35-40°C using condensed water; the condensed water temperature is 0-5°C, and the stirring speed is 30-40r / min.

[0011] Beneficial effects of the present invention: The invention can effectively retain the inherent nutrients in the oil while removing harmful plasticizer components in the raw materials on the premise of preparing walnut oil with a higher yield, thereby making the edible oil safer and more nutritious, and achieving the purpose of improving the quality of the edible oil. DETAILED DESCRIPTION

[0012] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Example 1

[0013] The walnut kernel raw material was microwave-dried at 100°C until the water content was 6% and the crushing particle size was 40 mesh. The crushed walnut powder was loaded into the No. 1 extraction kettle at a loading amount of 0.4Kg / L according to the bulk density. The equipment was adjusted to the start state, and the extraction parameters were set to extraction pressure 25MPa, extraction temperature 35°C, separation pressure 6MPa, and separation temperature 50°C. When the temperature reached the conditions, the pressure was increased at a rate of 1.5MPa per minute until the pressure reached 25MPa, and the circulation was started and data was recorded. When the No. 1 extraction kettle began to circulate, the extraction time was recorded, and the loading of the No. 2 extraction kettle was prepared at the same time. The loading amount was loaded according to the bulk density of 0.4Kg / L. After the loading was completed, the spare pressure pump was used to increase the pressure at a rate of 1.5MPa per minute until the pressure reached 25MPa. Increase the pressure at 1.5MPa per minute until the pressure reaches 25MPa, stop the pressure pump, close the inlet and outlet valves of No. 2 extraction kettle and start static extraction for 1.5h (pressure maintained at 25MPa), after the extraction time of No. 1 extraction kettle reaches 2 hours, open the inlet and outlet valves of No. 2 extraction kettle, switch to No. 1 kettle in series with No. 2 kettle at equal pressure, and No. 1 kettle continues to extract for 2 hours. After the extraction time of No. 1 extraction kettle is completed for 4 hours, stop and release the pressure. At the same time, No. 2 kettle has completed the extraction for 2 hours. After isobaric switching to No. 1 kettle in series with No. 2 kettle, start preparing for No. 3 kettle loading, pressure increase, static extraction for 1.5h (pressure maintained at 25MPa) and other operations until the extraction time of No. 2 kettle reaches 2 hours, isobaric switching to No. 2 kettle in series with No. 3 kettle, and No. 2 kettle continues to extract After 2 hours, after the extraction time of No. 2 extraction kettle is completed for 4 hours, it is shut down, depressurized, and switched to kettle No. 2 in series with kettle No. 3 at equal pressure. Then, preparations for the loading of kettle No. 1, pressurization, static extraction for 1.5 hours (pressure maintained at 25MPa) and other operations are started, until kettle No. 3 has completed extraction for 2 hours, and isobaric switch is switched to kettle No. 3 in series with kettle No. 1. Kettle No. 3 continues to extract for 2 hours. After the extraction time of extraction kettle No. 3 is completed for 4 hours, it is shut down, depressurized, and the heat transfer oil temperature of the extraction walnut oil tank is set to 100℃, and the stirring speed is 10r / min. After the walnut oil temperature is reached, heating and stirring are stopped, and precipitation is performed for 1 hour. The first-level distillation process of the three-stage molecular distillation is as follows: the heat transfer oil temperature is 100℃, the condensation surface temperature is 5℃, and the vacuum degree is 50Pa; the secondary distillation process is as follows: The hot oil temperature is 160°C, the condensation surface temperature is 5°C, the vacuum degree is 30Pa, and the three-stage distillation process is a heat transfer oil temperature of 200°C, a condensation surface temperature of 5°C, and a vacuum degree of 2Pa. After the parameters meet the conditions, the heated walnut oil is fed at a feeding rate of 30L / h. At the same time, the first-stage molecular distillation heavy component material pump frequency is set to 30HZ, and the light component material pump frequency is set to 20HZ, the second-stage molecular distillation heavy component material pump frequency is set to 30HZ, and the light component material pump frequency is set to 15HZ, the third-stage molecular distillation heavy component material pump frequency is set to 30HZ, and the light component material pump frequency is set to 10HZ. The temperature of the condensed water is set to 5°C and the stirring speed is 30r / min. The molecular distilled walnut oil is cooled and the stirring is stopped after the distilled walnut oil is cooled to room temperature. Example 2

[0014] The walnut kernel raw material was microwave-dried at 140°C until the water content was 8% and the crushing particle size was 45 meshes. The crushed walnut powder was loaded into the No. 1 extraction kettle at a loading amount of 0.45Kg / L according to the bulk density. The equipment was adjusted to the start-up state, and the extraction parameters were set to extraction pressure 30MPa, extraction temperature 40°C, separation pressure 9MPa, and separation temperature 55°C. When the temperature reached the conditions, the pressure was increased at a rate of 2MPa per minute until the pressure reached 30MPa, and the circulation was started and data was recorded. When the No. 1 extraction kettle started to circulate, the extraction time was recorded, and the loading of the No. 2 extraction kettle was prepared at the same time. The loading amount was loaded according to the bulk density of 0.45Kg / L. After the loading was completed, the spare pressure pump was used to increase the pressure at a rate of 2MPa per minute. The pressure was increased by 2 MPa per minute until it reached 30 MPa, the pressure pump was stopped, the inlet and outlet valves of the No. 2 extraction kettle were closed, and static extraction for 2 hours was started (the pressure was maintained at 30 MPa). After the extraction time of the No. 1 extraction kettle reached 2.5 hours, the inlet and outlet valves of the No. 2 extraction kettle were opened, and the No. 1 extraction kettle was switched to the No. 2 extraction kettle in series with the No. 1 extraction kettle at equal pressure. After the No. 1 extraction kettle continued to extract for 2.5 hours, the No. 1 extraction kettle was shut down and the pressure was released after the No. 2 extraction kettle had completed the extraction for 2.5 hours. After the No. 2 extraction kettle was switched to the No. 1 extraction kettle in series with the No. 2 extraction kettle at equal pressure and the No. 3 extraction kettle was prepared for loading, increasing pressure, and static extraction for 2 hours (the pressure was maintained at 30 MPa) until the No. 2 extraction kettle reached 2.5 hours. The No. 2 extraction kettle was switched to the No. 2 extraction kettle in series with the No. 3 extraction kettle at equal pressure and the No. 2 extraction kettle continued to extract for 2. After 5 hours, the extraction time of No. 2 extraction kettle is completed for 5 hours, and then the machine is shut down, the pressure is released, and the No. 2 kettle is switched to the No. 3 kettle in series at an equal pressure. Then, the No. 1 kettle is prepared for loading, pressurization, and static extraction for 2 hours (the pressure is maintained at 30MPa), etc., until the No. 3 kettle has completed extraction for 2.5 hours, and the No. 3 kettle is switched to the No. 3 kettle in series at an equal pressure. After the No. 3 extraction kettle is extracted for 2.5 hours, the No. 3 kettle is shut down and the pressure is released. The heat transfer oil temperature of the extraction walnut oil tank is set to 110℃, and the stirring speed is 15r / min. After the walnut oil temperature is reached, the heating and stirring are stopped, and the sedimentation is carried out for 1.5 hours. The first-level distillation process of the three-stage molecular distillation is set to a heat transfer oil temperature of 110℃, a condensation surface temperature of 5℃, and a vacuum degree of 60Pa; the second-level distillation process The heat transfer oil temperature is 170℃, the condensation surface temperature is 5℃, the vacuum degree is 40Pa, and the three-stage distillation process is 210℃, the condensation surface temperature is 5℃, and the vacuum degree is 1Pa. After the parameters are met, the heated walnut oil is fed at a feeding rate of 35L / h. At the same time, the first-stage molecular distillation heavy component material pump frequency is set to 30HZ, and the light component material pump frequency is set to 20HZ, the second-stage molecular distillation heavy component material pump frequency is set to 30HZ, and the light component material pump frequency is set to 15HZ, the third-stage molecular distillation heavy component material pump frequency is set to 30HZ, and the light component material pump frequency is set to 10HZ. The temperature of the condensed water is set to 5℃ and the stirring speed is 35r / min. The molecular distilled walnut oil is cooled and the stirring is stopped after the distilled walnut oil is cooled to room temperature. Example 3

[0015] The walnut kernel raw material was microwave-dried at 145°C until the water content was 10% and the crushing particle size was 50 mesh. The crushed walnut powder was loaded into the No. 1 extraction kettle at a loading amount of 0.5Kg / L according to the bulk density. The equipment was adjusted to the start-up state, and the extraction parameters were set to extraction pressure 40MPa, extraction temperature 45°C, separation pressure 12MPa, and separation temperature 55°C. When the temperature reached the conditions, the pressure was increased at a rate of 2MPa per minute until the pressure reached 40MPa, and the circulation was started and data was recorded. When the No. 1 extraction kettle began to circulate, the extraction time was recorded, and the loading of the No. 2 extraction kettle was prepared at the same time. The loading amount was loaded according to the bulk density of 0.5Kg / L. After the loading was completed, the spare pressure pump was used to increase the pressure at a rate of 2MPa per minute. The pressure is increased at a rate of 2MPa per minute until the pressure reaches 40MPa, the pressure pump is stopped, the inlet and outlet valves of No. 2 extraction kettle are closed, and static extraction for 2.5h is started (the pressure is maintained at 40MPa). After the extraction time of No. 1 extraction kettle reaches 3 hours, the inlet and outlet valves of No. 2 extraction kettle are opened, and the No. 1 kettle is switched to No. 2 kettle in series with No. 1 kettle at equal pressure. No. 1 kettle continues to extract for 3 hours. After the extraction time of No. 1 extraction kettle is completed for 6 hours, the machine is shut down and the pressure is released. At the same time, No. 2 kettle has completed the extraction for 3 hours. After the No. 1 kettle is switched to No. 1 kettle in series with No. 2 kettle at equal pressure, the No. 3 kettle is prepared for loading, pressurization, static extraction for 2.5h (the pressure is maintained at 40MPa) and other operations until the extraction time of No. 2 kettle reaches 3 hours. The No. 2 kettle is switched to No. 2 kettle in series with No. 3 kettle at equal pressure. No. 2 kettle continues to extract for 3 hours. After 6 hours, the extraction time of No. 2 extraction kettle is completed, the machine is shut down, the pressure is released, and the No. 2 kettle is switched to No. 3 kettle in series at equal pressure. Then, the No. 1 kettle is prepared for loading, pressurization, static extraction for 2.5 hours (pressure maintained at 40MPa) and other operations are started until No. 3 kettle has completed extraction for 3 hours, and the No. 3 kettle is switched to No. 3 kettle in series at equal pressure. No. 3 kettle continues to extract for 3 hours. After the extraction time of No. 3 extraction kettle is completed for 6 hours, the machine is shut down, the pressure is released, and the heat transfer oil temperature of the extraction walnut oil tank is set to 120℃, and the stirring speed is 20r / min. After the walnut oil temperature is reached, the heating and stirring are stopped, and the sedimentation is carried out for 2 hours. The first-level distillation process of the three-stage molecular distillation is set to a heat transfer oil temperature of 120℃, a condensation surface temperature of 5℃, and a vacuum degree of 80Pa; the secondary distillation process is a heat transfer oil The temperature is 180℃, the condensation surface temperature is 5℃, the vacuum degree is 50Pa, and the three-stage distillation process is a heat transfer oil temperature of 230℃, a condensation surface temperature of 5℃, and a vacuum degree of 0.8Pa. After the parameters meet the conditions, the heated walnut oil is fed at a feeding rate of 40L / h. At the same time, the first-stage molecular distillation heavy component material pump frequency is set to 30HZ, and the light component material pump frequency is set to 20HZ, the second-stage molecular distillation heavy component material pump frequency is set to 30HZ, and the light component material pump frequency is set to 15HZ, the third-stage molecular distillation heavy component material pump frequency is set to 30HZ, and the light component material pump frequency is set to 10HZ. The temperature of the condensed water is set to 5℃ and the stirring speed is 35r / min. The molecular distilled walnut oil is cooled and the stirring is stopped after the distilled walnut oil is cooled to room temperature.

[0016] Comparative Example 1: The walnut kernel raw material was microwave-dried at 100°C until the water content was 6% and the crushing particle size was 40 mesh. The crushed walnut powder was loaded into the No. 1 extraction kettle at a bulk density of 0.4Kg / L. The equipment was adjusted to the start-up state, and the extraction parameters were set to extraction pressure 25MPa, extraction temperature 35°C, separation pressure 6MPa, and separation temperature 50°C. After the temperature reached the conditions, the pressure was increased at a rate of 1.5MPa per minute until the pressure reached 25MPa. The circulation was started and the data was recorded until the total extraction time was 4 hours. Then the machine was shut down and the pressure was released. The heat transfer oil temperature of the extraction walnut oil tank was set to 100°C and the stirring speed was 10r / min. After the walnut oil temperature was reached, the heating and stirring were stopped and the mixture was allowed to settle for 1 hour. The three-stage molecular distillation and the first-stage distillation process were set to the heat transfer oil temperature of 100°C, The condensation surface temperature is 5°C and the vacuum degree is 50Pa; the secondary distillation process is a heat transfer oil temperature of 160°C, a condensation surface temperature of 5°C, and a vacuum degree of 30Pa; the tertiary distillation process is a heat transfer oil temperature of 200°C, a condensation surface temperature of 5°C, and a vacuum degree of 2Pa. After the parameters meet the conditions, the heated walnut oil is fed at a feeding rate of 30L / h. At the same time, the frequency modulation of the first-stage molecular distillation heavy component material pump is set to 30HZ, and the frequency modulation of the light component material pump is set to 20HZ, the frequency modulation of the second-stage molecular distillation heavy component material pump is set to 30HZ, and the frequency modulation of the light component material pump is set to 15HZ, the frequency modulation of the third-stage molecular distillation heavy component material pump is set to 30HZ, and the frequency modulation of the light component material pump is set to 10HZ. The temperature of the condensed water is set to 5°C and the stirring speed is 30r / min. The molecular distilled walnut oil is cooled and the stirring is stopped after the distilled walnut oil is cooled to room temperature.

[0017] Comparative Example 2: The difference between Example 2 and Example 1 is that the walnut kernel raw material is microwave-dried at 140°C to a water content of 8%, and the crushing particle size is 45 meshes. The crushed walnut powder is loaded into No. 1 extraction kettle, and the charging amount is charged according to the bulk density of 0.45Kg / L. The equipment is adjusted to the start-up state, and the extraction parameters are set to extraction pressure 30MPa, extraction temperature 40°C, separation pressure 9MPa, and separation temperature 55°C. After the temperature reaches the conditions, the pressure is increased, and the pressure increase rate is increased at 2MPa per minute until the pressure rises to 30MPa. The circulation is started and the data is recorded. After the total extraction time is 5 hours, the machine is shut down and the pressure is released. The heat transfer oil temperature of the extraction walnut oil tank is set to 110°C and the stirring speed is 15r / min. After the walnut oil temperature is reached, the heating and stirring are stopped, and the precipitation is 1.5 hours. The three-stage molecular distillation and the first-stage distillation process are set to the heat transfer oil temperature The temperature of the secondary distillation process is 110℃, the temperature of the condensation surface is 5℃, and the vacuum is 60Pa; the temperature of the secondary distillation process is 170℃ for the heat transfer oil, 5℃ for the condensation surface, and 40Pa for the vacuum; the temperature of the tertiary distillation process is 210℃ for the heat transfer oil, 5℃ for the condensation surface, and 1Pa for the vacuum. After the parameters meet the conditions, the heated walnut oil is fed at a feeding rate of 35L / h. At the same time, the frequency modulation of the first-stage molecular distillation heavy component material pump is 30HZ, and the frequency modulation of the light component material pump is 20HZ. The frequency modulation of the secondary molecular distillation heavy component material pump is 30HZ, and the frequency modulation of the light component material pump is 15HZ. The frequency modulation of the tertiary molecular distillation heavy component material pump is 30HZ, and the frequency modulation of the light component material pump is 10HZ. The temperature of the condensed water is set to 5℃ and the stirring speed is 35r / min. The molecular distilled walnut oil is cooled, and the stirring is stopped after the distilled walnut oil is cooled to room temperature.

[0018] Comparative Example 3: A highly efficient preparation process of walnut oil without plasticizer: walnut kernel raw material is microwave-dried at 145°C until the water content is 10%, the crushing particle size is 50 mesh, the crushed walnut powder is loaded into No. 1 extraction kettle, the loading amount is loaded according to the bulk density of 0.5 kg / L, the equipment is adjusted to the start state, the extraction parameters are set to extraction pressure of 40 MPa, extraction temperature of 45°C, separation pressure of 12 MPa, and separation temperature of 55°C, after the temperature reaches the conditions, the pressure is increased, and the pressure increase rate is increased at 2 MPa per minute until the pressure reaches 40 MPa, the circulation is started, and the data is recorded. After the total extraction time is 6 hours, the machine is stopped and the pressure is released, the temperature of the heat transfer oil in the extraction walnut oil tank is set to 120°C, the stirring speed is 20 r / min, after the temperature of the walnut oil is reached, the heating and stirring are stopped, and the precipitation is performed for 2 hours, and the three-stage molecular distillation and the first-stage distillation process are set to the heat transfer oil The temperature is 120℃, the condensation surface temperature is 5℃, and the vacuum degree is 80Pa; the secondary distillation process is a heat transfer oil temperature of 180℃, a condensation surface temperature of 5℃, and a vacuum degree of 50Pa; the tertiary distillation process is a heat transfer oil temperature of 230℃, a condensation surface temperature of 5℃, and a vacuum degree of 0.8Pa. After the parameters meet the conditions, the heated walnut oil is fed at a feeding rate of 40L / h. At the same time, the frequency modulation of the first-stage molecular distillation heavy component material pump is set to 30HZ, and the frequency modulation of the light component material pump is set to 20HZ, the frequency modulation of the second-stage molecular distillation heavy component material pump is set to 30HZ, and the frequency modulation of the light component material pump is set to 15HZ, the frequency modulation of the third-stage molecular distillation heavy component material pump is set to 30HZ, and the frequency modulation of the light component material pump is set to 10HZ, the temperature of the condensed water is set to 5℃, the stirring speed is 35r / min, the molecular distilled walnut oil is cooled, and the stirring is stopped after the distilled walnut oil is cooled to room temperature.

[0019] The above-mentioned embodiments 1-3 are specific embodiments of the present invention, and comparative examples 1-3 are conventional technical means.

[0020] Table 1 below is a comparison of experimental data between supercritical CO2 fluid isobaric switching extraction of walnut kernels and supercritical CO2 fluid extraction using a supercritical extraction 700L device as an example:

[0021] Table 1 From Table 1 above, it can be concluded that after isobaric switching, the extraction rate obtained by the static extraction scheme is higher than that of conventional means, and the amount of walnut kernels that can be processed per day is also increased by nearly 50%, and the work efficiency is significantly improved.

[0022] Table 2 below shows the content of various plasticizers in walnut raw materials:

[0023] Table 2 Table 3 below shows the content of various plasticizers in supercritical CO2 fluid isobaric switching extraction:

[0024] Table 3 It can be seen from Table 2 and Table 3 that the isobaric switching extraction combined with the three-stage molecular distillation of the present invention can prepare walnut oil with a higher yield, effectively retain the inherent nutrients in the oil, and remove the harmful plasticizer components in the raw materials, making the edible oil safer and more nutritious, thereby achieving the purpose of improving the quality of the edible oil.

[0025] The protection scope of the present invention is not limited to the technical solutions disclosed in the specific implementation methods. Any modifications, equivalent replacements, improvements, etc. made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. a preparation technology of walnut oil, the steps are as follows: After the walnut kernel raw material is pretreated, the pretreated walnut kernel is extracted by supercritical CO2 fluid isobaric switching, the walnut oil is heated after extraction, and then the walnut oil is molecularly distilled in three stages, and finally the distilled walnut oil is cooled.

2. A process for preparing walnut oil according to claim 1, characterized in that: The walnut kernel raw material pretreatment is to microwave dry the walnut kernel and then crush it to obtain walnut powder.

3. A preparation process for walnut oil according to claim 2, characterized in that: The microwave drying temperature is 100° C. to 180° C., and the microwave drying is performed until the moisture content is 5% to 10%; the crushing particle size is 20 to 60 meshes.

4. A process for preparing walnut oil according to claim 1 or 2, characterized in that: The walnut kernel supercritical CO2 fluid isobaric switching extraction is to put walnut powder into an extraction kettle, set the parameters of extraction pressure 15-55MPa, extraction temperature 30-45°C, separation pressure 6-15MPa, separation temperature 50-70°C, isobaric switching pressure 15-55MPa, isobaric switching time 2-3h, and extraction time 4-6h.

5. A process for preparing walnut oil according to claim 1, characterized in that: The temperature of the heat-conducting oil in the heating of the extracted walnut oil is 100-120° C., the stirring speed is 10-30 r / min, the heating time is 10-30 min, and the precipitation time is 1-6 hours.

6. A process for preparing walnut oil according to claim 1, characterized in that: The first-stage distillation process in the three-stage molecular distillation of walnut oil is as follows: the feed rate is 20-60L / h, the heat transfer oil temperature is 100-120°C, the condensation surface temperature is 0-35°C, the vacuum degree is 30-100Pa, the heavy component material pump frequency is 30-35HZ, and the light component material pump frequency is 10-20HZ; the second-stage distillation process is as follows: the heat transfer oil temperature is 120-200°C, the condensation surface temperature is 0-35°C, the vacuum degree is 10-50Pa, the heavy component material pump frequency is 30-35HZ, and the light component material pump frequency is 20-30HZ; the third-stage distillation process is as follows: the heat transfer oil temperature is 200-240°C, the condensation surface temperature is 0-35°C, the vacuum degree is 0.1-5Pa, the heavy component material pump frequency is 30-35HZ, and the light component material pump frequency is 10-20HZ.

7. A process for preparing walnut oil according to claim 1, characterized in that: The distilled walnut oil cooling: the distilled walnut oil is rapidly cooled to 35-40° C. using condensed water.

8. A process for preparing walnut oil according to claim 7, characterized in that: The condensed water temperature is 0-5°C, and the stirring speed is 30-40r / min.

Images