Method for refining and removing impurities of torreya grandis seeds by gradient pressing

Abstract

The application discloses a method for refining and removing impurities from Chinese torreya seed kernels by gradient pressing, and at least comprises the following steps: S3, segment refining: pumping the mixed Chinese torreya crude oil obtained in step S2 into a refining system, and sequentially performing low-temperature step-by-step treatment in the following five stages: S3.1, enzymatic ultrasonic low-temperature degumming: adding water and a composite enzyme preparation into the mixed Chinese torreya crude oil, stirring to form a mixed emulsion, controlling the reaction temperature of the mixed emulsion to be 40-45 DEG C, applying ultrasonic cavitation treatment for 30-40 minutes, then centrifugally separating and removing gum to obtain degummed oil. The application adopts low-temperature step-by-step segment refining, and through five-step low-temperature step-by-step synergistic refining of degumming, deacidification, decolorization, deodorization and dewaxing, an integrated synergistic impurity removal system is formed: enzymatic ultrasonic degumming completely removes gum, provides low-impurity and high-quality oil phase raw materials for the subsequent deacidification section, reduces the interference of impurities on the mass transfer efficiency of microbubble stripping, and lays the foundation for synergistic impurity removal.

Description

Technical Field

[0001] This invention belongs to the field of Torreya grandis technology, and particularly relates to a method for gradient pressing, refining and impurity removal of Torreya grandis kernels. Background Technology

[0002] Torreya oil, as a high-value oil from a woody nut, is rich in nutrients, has a unique flavor, and is rich in unsaturated fatty acids and a variety of active functional ingredients, giving it high nutritional and health benefits.

[0003] Existing refining and impurity removal processes are mostly simple combinations of single stages, with each stage operating independently and lacking a tiered, synergistic treatment system. This not only makes it difficult to simultaneously and efficiently remove multiple impurities such as gums, free fatty acids, pigments, odor substances, and waxes, but also easily leads to problems such as oil oxidation, darkening of color, low-temperature turbidity and wax precipitation, and loss of active nutrients during processing. As a result, it is difficult to meet the needs of refined and large-scale production of high-quality Torreya grandis oil. Summary of the Invention

[0004] To address the problems in the prior art, the present invention proposes the following technical solution: This invention provides a method for refining and removing impurities from Torreya grandis kernels by gradient pressing, comprising at least the following steps: S3 Segmented Refining: The mixed crude torreya oil obtained in step S2 is pumped into the refining system and subjected to the following five stages of low-temperature step processing: S3.1 Enzymatic ultrasonic low-temperature degumming: Water and compound enzyme preparation are added to the mixed crude torreya oil, and the mixture is stirred to form a mixed emulsion. The reaction temperature of the mixed emulsion is controlled at 40℃~45℃. Ultrasonic cavitation treatment is applied for 30 minutes~40 minutes, followed by centrifugation to remove the gum and obtain degummed oil. S3.2 Microbubble Gentle Deacidification: Following the degummed oil obtained in the previous step, it is first pretreated through a precision filter with an accuracy of 30μm~50μm. The oil phase temperature is controlled at 70℃~80℃, and the system vacuum is maintained at -0.085MPa~-0.092MPa. Micro-nano water vapor bubbles are injected into the oil phase through a wide-channel Venturi tube or a dynamic shear microbubble generator for physical stripping. Subsequently, free fatty acids are removed by centrifugation to obtain deacidified oil. S3.3 Dynamic constant temperature decolorization: Continuing with the deacidified oil obtained in the previous step, the oil temperature is controlled at 70℃~75℃, and the vacuum degree is maintained at ≥0.096MPa. Adsorbent is added to the mechanical scraper reactor and stirred for adsorption for 30~40 minutes. The pigment is removed by filtration to obtain decolorized oil. S3.4 Multi-stage thin-film low-temperature deodorization: Continuing with the decolorized oil obtained in the previous step, the oil temperature is controlled at 115℃~125℃, and the vacuum degree is maintained at ≤50Pa. Direct steam stripping is carried out in a falling film deodorization tower for 90 to 120 minutes to remove odors and volatile harmful substances, thus obtaining deodorized oil. S3.5 Gradient Winterization Dewaxing: Following the deodorized oil obtained in the previous step, the oil temperature is slowly reduced to 6℃~8℃ through programmed temperature control, and kept warm for crystal growth for 18 to 24 hours. The wax is removed by filtration in a closed temperature-controlled filtration system to obtain the finished Torreya grandis oil.

[0005] As a preferred embodiment of the above technical solution, the following steps are included: S1 Grading and Pretreatment: Remove the shells from the raw materials of Torreya grandis and separate them. Dry the kernels to a moisture content of 4% to 5%. Crush and sieve the shells to obtain coarse shell powder of 20-40 mesh and fine shell powder of 60-80 mesh, and dry them separately for later use. S2 gradient pressing for impurity control: S2.1 Grade 1 Pure Kernel Cold Press: The kernels are pressed at 40℃~45℃ and 10MPa~15MPa to obtain Grade 1 crude oil and Grade 1 cake. S2.2 Secondary Friction Re-pressing: After crushing the primary oil cake, it is mixed with coarse shell powder at a mass ratio of 15:1 and pressed at 60℃~65℃ and 25MPa~30MPa to obtain secondary crude oil and secondary oil cake. S2.3 Tertiary Cake Deep Pressing: After crushing the secondary cake, it is pressed at 50℃~55℃ and 35MPa~40MPa without adding exogenous filter aids to obtain tertiary crude oil; S2.4 Crude Oil Merging: Merge Grade I, II, and III crude oils to obtain mixed Torreya grandis crude oil; pump the mixed Torreya grandis crude oil into a temporary storage tank and keep it at 40℃~50℃ for 2h~4h to homogenize the oil temperature and allow it to undergo preliminary gravity settling. Then, coarsely filter it through an 80-100 mesh vibrating screen or leaf filter to remove micron-sized solid suspended matter, and obtain pretreated mixed Torreya grandis crude oil.

[0006] S3 segmented refining; S4 High-value recovery of by-products: The colloid residue, soap residue, waste clay and wax residue generated in each stage of step S3 are collected separately, and residual oils, phospholipids, pine acid derivatives and torreya wax are recovered by solvent extraction or recrystallization processes.

[0007] As a preferred embodiment of the above technical solution, in step S3.1, the compound enzyme preparation is composed of pectinase and phospholipase in a mass ratio of 1:2 to 1:3, and the amount added is 0.05% to 0.1% of the mass of the pretreated mixed Torreya grandis crude oil; Adjust the pH of the mixed emulsion to 5.5-6.0, and add water at a rate of 2%-4% of the mass of the pretreated mixed Torreya grandis crude oil; The ultrasonic cavitation treatment frequency is 20kHz~40kHz, the power density is 0.4W / mL~0.8W / mL, and a pulse mode of 3 seconds working and 2 seconds pausing is adopted.

[0008] As a preferred embodiment of the above technical solution, in step S3.2, the average diameter of the micro-nano water vapor bubbles is 10μm~50μm, and the steam introduction rate is 1.5%~2.5% of the mass of the degumming oil.

[0009] As a preferred embodiment of the above technical solution, in step S3.3, the adsorbent is composed of activated clay and powdered activated carbon in a mass ratio of 8:1 to 9:1, and the total amount added is 0.8% to 1.2% of the mass of the deacidified oil. As a preferred embodiment of the above technical solution, the scraper rotation speed of the mechanical scraper reactor is 60r / min to 100r / min to ensure that the oil film thickness is controlled within 1mm to 2mm.

[0010] As a preferred embodiment of the above technical solution, in step S3.4, the operating vacuum of the falling film deodorization tower is maintained at 20Pa~50Pa; the amount of direct steam introduced is 2.0%~3.0% of the mass of the decolorized oil, and the steam temperature is 160℃~180℃.

[0011] As a preferred embodiment of the above technical solution, in step S3.5, the cooling process is divided into two stages: the first stage cools the temperature from the deodorization temperature to 15℃ at a rate of 2℃ / h to 3℃ / h; the second stage cools the temperature from 15℃ to 6℃ to 8℃ at a rate of 0.5℃ / h to 1℃ / h.

[0012] As a preferred embodiment of the above technical solution, in step S3.5, the closed temperature-controlled filtration system is equipped with a chilled brine jacket to maintain the internal temperature of the filter and the surface temperature of the filter cloth ≤10℃, and uses polypropylene filter cloth with a filtration accuracy of 3μm~5μm.

[0013] The beneficial effects of this invention are as follows: (1) This invention adopts a low-temperature stepped segmented refining process, which forms an integrated synergistic impurity removal system through five steps of low-temperature stepped synergistic refining: enzymatic ultrasonic degumming thoroughly removes gums, providing low-impurity, high-quality oil phase raw materials for the subsequent deacidification stage, reducing the interference of impurities on the mass transfer efficiency of microbubble stripping, and laying the foundation for synergistic impurity removal; microbubble gentle deacidification efficiently removes free fatty acids at low temperatures, avoiding oil oxidation and discoloration, and creating a stable oil phase for subsequent decolorization; dynamic constant temperature decolorization makes adsorption more uniform and sufficient, further improving the purity of the oil; multi-stage thin-film low-temperature deodorization removes odors under gentle conditions, and retains nutrients and flavor to the greatest extent; finally, program gradient winterization dewaxing achieves deep separation of waxes, significantly improving low-temperature stability.

[0014] (2) This invention employs a gradient pressing and impurity control section, using a three-stage step-by-step pressing process in conjunction with crude oil pretreatment: the first stage involves low-temperature cold pressing of pure kernels to preferentially extract high-quality crude oil under mild conditions, avoiding the large-scale mixing of kernel impurities; the second stage involves repressing by adding self-produced coarse shell powder as a friction aid, which not only increases the oil yield but also utilizes the shell powder to adsorb some solid impurities, avoiding pollution caused by external filter aids; the third stage involves deep pressing without external aids to further extract residual oil from the cake, improving resource utilization. Subsequently, the oil temperature is homogenized by heat preservation and static settling, and impurities are initially settled. Combined with coarse filtration, micron-sized solid suspended matter is efficiently removed, providing low-impurity, high-quality oil phase raw materials for subsequent staged refining, reducing the interference of impurities on the mass transfer efficiency of processes such as microbubble stripping, decolorization, and dewaxing, and laying a stable foundation for synergistic impurity removal. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Example 1

[0016] A method for refining and removing impurities from Torreya grandis seeds by gradient pressing, the specific steps of which are as follows: S1 graded cleaning and pretreatment: The raw material of Torreya grandis was shelled and separated, and the kernels were dried to a moisture content of 4%. The shells were crushed and sieved to obtain coarse shell powder of 20 mesh and fine shell powder of 60 mesh, which were dried separately for later use.

[0017] S2 gradient pressing for impurity control: S2.1 Grade 1 Pure Kernel Cold Press: The kernels are pressed at 40℃ and 10MPa to obtain Grade 1 crude oil and Grade 1 cake. S2.2 Secondary Friction Re-pressing: After crushing the primary cake, the above coarse shell powder is mixed in at a mass ratio of 15:1 and pressed at 60℃ and 25MPa to obtain secondary crude oil and secondary cake.

[0018] S2.3 Tertiary Cake Deep Pressing: After crushing the secondary cake, it is directly pressed again at 50℃ and 35MPa without adding any shell powder or exogenous filter aid to obtain tertiary crude oil.

[0019] S2.4 Crude Oil Merging and Pretreatment: Grade I, II, and III crude oils were merged to obtain mixed Torreya grandis crude oil. This oil was pumped into a temporary storage tank and kept at 40°C for 2 hours for initial gravity settling. Subsequently, it was coarsely filtered through an 80-mesh vibrating screen to remove micron-sized suspended solids, yielding pretreated mixed Torreya grandis crude oil.

[0020] S3 Segmented Refinement: S3.1 Enzymatic Ultrasonic Low-Temperature Degumming: Water and a compound enzyme preparation (pectinase and phospholipase mass ratio 1:2, addition amount 0.05%) were added to the mixed crude torreya oil. The pH was adjusted to 5.5, and the amount of water added was 2% of the oil mass. The mixture was stirred to form an emulsion, and the temperature was controlled at 40℃. Ultrasonic cavitation treatment (frequency 20kHz, power density 0.4W / mL, pulse mode with 3 seconds of operation and 2 seconds of pause) was applied for 30 minutes. The gum was removed by centrifugation to obtain degummed oil.

[0021] S3.2 Microbubble Gentle Deacidification: The degummed oil is first pretreated through a precision filter with an accuracy of 30μm. The oil temperature is controlled at 70℃ and the vacuum degree is -0.085MPa. Micro-nano water vapor bubbles with an average diameter of 10μm (steam flow rate 1.5%) are injected through a wide-channel Venturi tube for physical stripping. Free fatty acids are removed by centrifugation to obtain deacidified oil.

[0022] S3.3 Dynamic Constant Temperature Decolorization: The deacidified oil temperature is controlled at 70℃ and the vacuum degree is 0.096MPa. Adsorbent (activated clay and powdered activated carbon in a mass ratio of 8:1, total addition amount 0.8%) is added to a mechanical scraper reactor. The scraper speed is 60r / min (oil film thickness 1mm), and the mixture is stirred and adsorbed for 30 minutes. The pigment is removed by filtration to obtain decolorized oil.

[0023] S3.4 Multi-stage thin-film low-temperature deodorization: The decolorized oil temperature is controlled at 115℃ and the vacuum degree is 50Pa. A falling film deodorization tower is used to pass direct steam (2.0% flow rate, 160℃ steam temperature) for 90 minutes to remove odors and volatile harmful substances, resulting in deodorized oil.

[0024] S3.5 Gradient Winterization Dewaxing: The deodorized oil is cooled by programmed temperature control: the first stage cools to 15℃ at a rate of 2℃ / h; the second stage cools to 6℃ at a rate of 0.5℃ / h. Crystallization is carried out at 6℃ for 18 hours. Wax is removed by filtration using a 3μm precision polypropylene filter cloth in a closed temperature-controlled filtration system equipped with a chilled brine jacket (internal temperature ≤10℃) to obtain the finished Torreya grandis oil.

[0025] High-value recovery of S4 byproducts: The colloid residue, soap residue, waste bleaching clay and wax residue generated in each stage of S3 were collected separately, and residual oils, phospholipids, pine acid derivatives and torreya wax were recovered by solvent extraction or recrystallization processes. Example 2

[0026] A method for refining and removing impurities from Torreya grandis seeds by gradient pressing, the specific steps of which are as follows: S1 graded cleaning and pretreatment: The raw material of Torreya grandis was shelled and separated, and the kernels were dried to a moisture content of 4.5%. The shells were crushed and sieved to obtain coarse shell powder of 30 mesh and fine shell powder of 70 mesh, which were dried separately for later use.

[0027] S2 gradient pressing for impurity control: S2.1 Grade 1 Pure Kernel Cold Press: The kernels are pressed at 42℃ and 12MPa to obtain Grade 1 crude oil and Grade 1 cake.

[0028] S2.2 Secondary Friction Re-pressing: After crushing the primary cake, the above coarse shell powder is mixed in at a mass ratio of 15:1 and pressed at 62℃ and 27MPa to obtain secondary crude oil and secondary cake.

[0029] S2.3 Tertiary Cake Deep Pressing: After crushing the secondary cake, it is directly pressed again at 52℃ and 37MPa without adding any shell powder or exogenous filter aid to obtain tertiary crude oil.

[0030] S2.4 Crude Oil Merging and Pretreatment: Grade I, II, and III crude oils were merged to obtain mixed Torreya grandis crude oil. This oil was pumped into a temporary storage tank and kept at 45°C for 3 hours for initial gravity settling. Subsequently, it was coarsely filtered through a 90-mesh vibrating screen to remove micron-sized suspended solids, yielding pretreated mixed Torreya grandis crude oil.

[0031] S3 Segmented Refinement: S3.1 Enzymatic Ultrasonic Low-Temperature Degumming: Water and a compound enzyme preparation (pectinase and phospholipase mass ratio 1:2.5, addition amount 0.075%) were added to the mixed crude torreya oil, and the pH was adjusted to 5.8. The amount of water added was 3% of the oil mass. The mixture was stirred to form an emulsion, and the temperature was controlled at 42℃. Ultrasonic cavitation treatment (frequency 28kHz, power density 0.6W / mL, pulse mode with 3 seconds of operation and 2 seconds of pause) was applied for 35 minutes. The gum was removed by centrifugation to obtain degummed oil.

[0032] S3.2 Microbubble Gentle Deacidification: The degummed oil is first pretreated through a precision filter with a precision of 40μm. The oil temperature is controlled at 75℃ and the vacuum degree is -0.088MPa. Micro-nano water vapor bubbles with an average diameter of 30μm (steam flow rate 2.0%) are injected through a wide-channel Venturi tube for physical stripping. Free fatty acids are removed by centrifugation to obtain deacidified oil.

[0033] S3.3 Dynamic Constant Temperature Decolorization: The deacidified oil temperature is controlled at 72℃ and the vacuum degree is 0.097MPa. Adsorbent (activated clay and powdered activated carbon mass ratio 8.5:1, total addition 1.0%) is added to a mechanical scraper reactor. The scraper speed is 80r / min (oil film thickness 1.5mm), and the mixture is stirred and adsorbed for 35 minutes. The pigment is removed by filtration to obtain decolorized oil.

[0034] S3.4 Multi-stage thin-film low-temperature deodorization: The decolorized oil temperature is controlled at 120℃ and the vacuum degree is 35Pa. A falling film deodorization tower is used to introduce direct steam (2.5% flow rate, 170℃ steam temperature) for stripping for 105 minutes to remove odors and volatile harmful substances, resulting in deodorized oil.

[0035] S3.5 Gradient Winterization Dewaxing: The deodorized oil is cooled by programmed temperature control: the first stage cools to 15℃ at a rate of 2.5℃ / h; the second stage cools to 7℃ at a rate of 0.8℃ / h. Crystallization is carried out at 7℃ for 20 hours. Wax is removed by filtration using a 4μm precision polypropylene filter cloth in a closed temperature-controlled filtration system equipped with a chilled brine jacket (internal temperature ≤10℃) to obtain the finished Torreya grandis oil.

[0036] High-value recovery of S4 byproducts: The colloid residue, soap residue, waste bleaching clay and wax residue generated in each stage of S3 were collected separately, and residual oils, phospholipids, pine acid derivatives and torreya wax were recovered by solvent extraction or recrystallization processes. Example 3

[0037] A method for refining and removing impurities from Torreya grandis seeds by gradient pressing, the specific steps of which are as follows: S1 graded cleaning and pretreatment: The raw material of Torreya grandis was shelled and separated, and the kernels were dried to a moisture content of 5%. The shells were crushed and sieved to obtain coarse shell powder of 40 mesh and fine shell powder of 80 mesh, which were dried separately for later use.

[0038] S2 gradient pressing for impurity control: S2.1 Grade 1 Pure Kernel Cold Press: The kernels are pressed at 45℃ and 15MPa to obtain Grade 1 crude oil and Grade 1 cake.

[0039] S2.2 Secondary Friction Re-pressing: After crushing the primary cake, the above coarse shell powder is mixed in at a mass ratio of 15:1 and pressed at 65℃ and 30MPa to obtain secondary crude oil and secondary cake.

[0040] S2.3 Tertiary Cake Deep Pressing: After crushing the secondary cake, it is directly pressed again at 55℃ and 40MPa without adding any shell powder or exogenous filter aid to obtain tertiary crude oil.

[0041] S2.4 Crude Oil Merging and Pretreatment: Grade I, II, and III crude oils were merged to obtain mixed Torreya grandis crude oil. This oil was pumped into a temporary storage tank and kept at 50°C for 4 hours for initial gravity settling. Subsequently, it was coarsely filtered through a 100-mesh leaf filter to remove micron-sized suspended solids, yielding pretreated mixed Torreya grandis crude oil.

[0042] S3 Segmented Refinement: S3.1 Enzymatic Ultrasonic Low-Temperature Degumming: Water and a compound enzyme preparation (pectinase and phospholipase mass ratio 1:3, addition amount 0.1%) were added to the mixed crude torreya oil. The pH was adjusted to 6.0, and the amount of water added was 4% of the oil mass. The mixture was stirred to form an emulsion, and the temperature was controlled at 45℃. Ultrasonic cavitation treatment (frequency 40kHz, power density 0.8W / mL, pulse mode with 3 seconds of operation and 2 seconds of pause) was applied for 40 minutes. The gum was removed by centrifugation to obtain degummed oil.

[0043] S3.2 Microbubble Gentle Deacidification: The degummed oil is first pretreated through a precision filter with an accuracy of 50μm. The oil temperature is controlled at 80℃ and the vacuum degree at -0.092MPa. Micro-nano water vapor bubbles with an average diameter of 50μm (steam flow rate of 2.5%) are injected through a dynamic shear-type microbubble generator for physical stripping. Free fatty acids are removed by centrifugation to obtain deacidified oil.

[0044] S3.3 Dynamic Constant Temperature Decolorization: The deacidified oil temperature is controlled at 75℃, and the vacuum degree is 0.098MPa (≥0.096MPa). Adsorbent (activated clay and powdered activated carbon mass ratio 9:1, total addition 1.2%) is added to a mechanical scraper reactor. The scraper speed is 100r / min (oil film thickness 2mm), and the mixture is stirred and adsorbed for 40 minutes. The pigments are removed by filtration to obtain the decolorized oil.

[0045] S3.4 Multi-stage thin-film low-temperature deodorization: The decolorized oil temperature is controlled at 125℃, and the vacuum degree is 20Pa (≤50Pa). A falling film deodorization tower is used to pass direct steam (3.0% flow rate, 180℃ steam temperature) for stripping for 120 minutes to remove odors and volatile harmful substances, thus obtaining deodorized oil.

[0046] S3.5 Gradient Winterization Dewaxing: The deodorized oil is cooled by programmed temperature control: the first stage cools to 15℃ at a rate of 3℃ / h; the second stage cools to 8℃ at a rate of 1℃ / h. Crystallization is carried out at 8℃ for 24 hours. Wax is removed by filtration using a 5μm precision polypropylene filter cloth in a closed temperature-controlled filtration system equipped with a chilled brine jacket (internal temperature ≤10℃) to obtain the finished Torreya grandis oil.

[0047] Comparative Example 1 The only difference between this comparative example and Example 2 is that in step S3.2 deacidification treatment, the oil temperature of this section is raised to 85°C and then natural deacidification is carried out by conventional mechanical stirring. All other steps and parameters are the same as in Example 2.

[0048] Comparative Example 2 The only difference between this comparative example and Example 2 is that in step S3.5 winterization filtration, a single-pore size filter cloth is used directly for atmospheric pressure gravity filtration at the same crystallization temperature; the remaining steps and all parameters are the same as in Example 2.

[0049] The physicochemical properties of the Torreya grandis finished oil obtained from Examples 1-3 and Comparative Examples 1-2 of this application are shown in Table 1 below: The color is determined by the Lovibond colorimetric method, the peroxide value test method refers to GB / T5538, and the antifreeze test method refers to GB / T17756-1999.

[0050] Table 1 As can be seen from Table 1, the Torreya grandis oils prepared in Examples 1-3 of this application have significantly better color, acid value, antifreeze stability and peroxide value than those in Comparative Examples 1-2. This proves that the present invention can achieve efficient impurity removal and improve the quality stability of Torreya grandis oil through the synergistic technical solution of gradient pressing and segmented refining.

[0051] The yellow value (Y) of Examples 1 to 3 was controlled between 24.0 and 27.5, and the red value (R) was as low as 1.8 to 2.4. The oil was light yellow and had a strong sense of transparency. The color of Comparative Example 1 was significantly darker (33.0:3.6), and Comparative Example 2 was also slightly darker than Examples 1 (28.0:2.6).

[0052] This invention employs the S3.1 enzymatic ultrasonic low-temperature degumming and the S3.3 dynamic isothermal decolorization process, creating a clean substrate for subsequent decolorization. The ultrasonic cavitation effect enhances enzymatic hydrolysis efficiency and avoids pigment fixation caused by high-temperature degumming. The mechanical scraper reactor ensures uniform contact between the adsorbent and the oil, efficiently removing heat-sensitive pigments such as chlorophyll and carotenoids under mild conditions of 70-75℃. In contrast, Comparative Example 1, due to the increased deacidification temperature to 85℃, accelerated the Maillard reaction and pigment polymerization, resulting in a reddish and darkened oil color. This invention's process achieves deep decolorization while avoiding color deterioration caused by overheating.

[0053] The microbubble gentle deacidification technology of this invention (S3.2) injects micro-nano water vapor bubbles through a venturi tube, which greatly increases the contact surface area between the stripping medium and free fatty acids, enabling efficient physical deacidification at a relatively low temperature of 70-80℃. In Comparative Example 1, although the temperature was increased, relying solely on conventional mechanical stirring resulted in low mass transfer efficiency and incomplete deacidification; in Comparative Example 2, although the deacidification process was the same, subsequent atmospheric pressure filtration may lead to trace hydrolysis or impurity residues.

[0054] This process utilizes a multi-stage, highly coordinated system of gradient pressing for impurity control, segmented gentle refining, and programmed gradient winterization dewaxing to form an integrated impurity removal and quality preservation system. The initial three-stage gradient pressing extracts oil step-by-step at low temperatures and pre-removes solid coarse impurities and gum precursors, reducing the refining load and preventing initial oxidation of the feedstock. The middle stage employs a series of gentle refining processes: enzymatic ultrasonic degumming, microbubble stripping deacidification, dynamic membrane decolorization, and low-temperature high-vacuum deodorization. Each unit precisely removes gums, free fatty acids, pigments, and volatile impurities at suitable low temperatures, with interconnected processes reducing the risk of high-temperature retention and oxidation. The final stage uses gradient temperature-controlled crystallization to allow wax to grow into large, easily filterable crystals, combined with gradient negative pressure closed filtration for deep dewaxing. The entire process is conducted at low temperatures with closed systems and inert gas protection to further prevent oxygen contact. The processes are not simply superimposed; rather, the preceding processes create ideal treatment conditions of low impurities, low temperature, and low oxygen for the subsequent processes. The subsequent processes achieve more efficient deep purification and quality protection based on the preceding processes, ultimately achieving efficient removal of free fatty acids, pigments, waxes, and solid impurities, while maximizing the inhibition of oil oxidation. This results in finished torreya oil that is superior to traditional processes in terms of acid value, color, low-temperature stability, and oxidative stability, achieving a balance between efficient impurity removal and preservation of nutritional quality.

[0055] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it.

Claims

1. A method for refining and removing impurities from Torreya grandis seeds by gradient pressing, characterized in that, At least the following steps are included: S3 Segmented Refining: The mixed crude torreya oil obtained in step S2 is pumped into the refining system and subjected to the following five stages of low-temperature step processing: S3.1 Enzymatic ultrasonic low-temperature degumming: Water and compound enzyme preparation are added to the mixed crude torreya oil, and the mixture is stirred to form a mixed emulsion. The reaction temperature of the mixed emulsion is controlled at 40℃~45℃. Ultrasonic cavitation treatment is applied for 30 minutes~40 minutes, followed by centrifugation to remove the gum and obtain degummed oil. S3.2 Microbubble Gentle Deacidification: Following the degummed oil obtained in the previous step, it is first pretreated through a precision filter with an accuracy of 30μm~50μm. The oil phase temperature is controlled at 70℃~80℃, and the system vacuum is maintained at -0.085MPa~-0.092MPa. Micro-nano water vapor bubbles are injected into the oil phase through a wide-channel Venturi tube or a dynamic shear microbubble generator for physical stripping. Subsequently, free fatty acids are removed by centrifugation to obtain deacidified oil. S3.3 Dynamic constant temperature decolorization: Continuing with the deacidified oil obtained in the previous step, the oil temperature is controlled at 70℃~75℃, and the vacuum degree is maintained at ≥0.096MPa. Adsorbent is added to the mechanical scraper reactor and stirred for adsorption for 30~40 minutes. The pigment is removed by filtration to obtain decolorized oil. S3.4 Multi-stage thin-film low-temperature deodorization: Continuing with the decolorized oil obtained in the previous step, the oil temperature is controlled at 115℃~125℃, and the vacuum degree is maintained at ≤50Pa. Direct steam stripping is carried out in a falling film deodorization tower for 90 to 120 minutes to remove odors and volatile harmful substances, thus obtaining deodorized oil. S3.5 Gradient Winterization Dewaxing: Following the deodorized oil obtained in the previous step, the oil temperature is slowly reduced to 6℃~8℃ through programmed temperature control, and kept warm for crystal growth for 18 to 24 hours. The wax is removed by filtration in a closed temperature-controlled filtration system to obtain the finished Torreya grandis oil.

2. The method for gradient pressing, refining, and impurity removal of Torreya grandis kernels according to claim 1, characterized in that, Includes the following steps: S1 Grading and Pretreatment: Remove the shells from the raw materials of Torreya grandis and separate them. Dry the kernels to a moisture content of 4% to 5%. Crush and sieve the shells to obtain coarse shell powder of 20-40 mesh and fine shell powder of 60-80 mesh, and dry them separately for later use. S2 gradient pressing for impurity control: S2.1 Grade 1 Pure Kernel Cold Press: The kernels are pressed at 40℃~45℃ and 10MPa~15MPa to obtain Grade 1 crude oil and Grade 1 cake. S2.2 Secondary Friction Re-pressing: After crushing the primary oil cake, it is mixed with coarse shell powder at a mass ratio of 15:1 and pressed at 60℃~65℃ and 25MPa~30MPa to obtain secondary crude oil and secondary oil cake. S2.3 Tertiary Cake Deep Pressing: After crushing the secondary cake, it is pressed at 50℃~55℃ and 35MPa~40MPa without adding exogenous filter aids to obtain tertiary crude oil; S2.4 Crude Oil Merging: Merge Grade I, II, and III crude oils to obtain mixed Torreya grandis crude oil; pump the mixed Torreya grandis crude oil into a temporary storage tank and keep it at 40℃~50℃ for 2h~4h to homogenize the oil temperature and allow it to undergo preliminary gravity settling. Then, coarsely filter it through an 80-100 mesh vibrating screen or leaf filter to remove micron-sized solid suspended matter, and obtain pretreated mixed Torreya grandis crude oil.

3. S3 segmented refining; S4 High-value recovery of by-products: The colloid residue, soap residue, waste clay and wax residue generated in each stage of step S3 are collected separately, and residual oils, phospholipids, pine acid derivatives and torreya wax are recovered by solvent extraction or recrystallization processes.

4. The method for gradient pressing, refining, and impurity removal of Torreya grandis kernels according to claim 2, characterized in that, In step S3.1, the compound enzyme preparation is composed of pectinase and phospholipase in a mass ratio of 1:2 to 1:3, and the amount added is 0.05% to 0.1% of the mass of the pretreated mixed crude torreya oil. Adjust the pH of the mixed emulsion to 5.5-6.0, and add water at a rate of 2%-4% of the mass of the pretreated mixed Torreya grandis crude oil; The ultrasonic cavitation treatment frequency is 20kHz~40kHz, the power density is 0.4W / mL~0.8W / mL, and a pulse mode of 3 seconds working and 2 seconds pausing is adopted.

5. The method for gradient pressing, refining, and impurity removal of Torreya grandis kernels according to claim 1, characterized in that, In step S3.2, the average diameter of the micro-nano water vapor bubbles is 10μm~50μm, and the steam introduction rate is 1.5%~2.5% of the mass of the degumming oil.

6. The method for gradient pressing, refining, and impurity removal of Torreya grandis kernels according to claim 1, characterized in that, In step S3.3, the adsorbent is a compound of activated clay and powdered activated carbon in a mass ratio of 8:1 to 9:1, and the total amount added is 0.8% to 1.2% of the mass of the deacidified oil. The scraper speed of the mechanical scraper reactor is 60r / min to 100r / min to ensure that the oil film thickness is controlled at 1mm to 2mm.

7. The method for gradient pressing, refining, and impurity removal of Torreya grandis kernels according to claim 1, characterized in that, In step S3.4, the operating vacuum of the falling film deodorization tower is maintained at 20 Pa to 50 Pa; the amount of direct steam introduced is 2.0% to 3.0% of the mass of the decolorized oil, and the steam temperature is 160°C to 180°C.

8. The method for gradient pressing, refining, and impurity removal of Torreya grandis kernels according to claim 1, characterized in that, In step S3.5, the cooling process is divided into two stages: the first stage cools the temperature from the deodorization temperature to 15℃ at a rate of 2℃ / h to 3℃ / h; the second stage cools the temperature from 15℃ to 6℃ to 8℃ at a rate of 0.5℃ / h to 1℃ / h.

9. The method for gradient pressing, refining, and impurity removal of Torreya grandis kernels according to claim 1, characterized in that, In step S3.5, the sealed temperature-controlled filtration system is equipped with a chilled brine jacket to maintain the internal temperature of the filter and the surface temperature of the filter cloth at ≤10℃, and uses polypropylene filter cloth with a filtration accuracy of 3μm~5μm.

Images