A device for preparing diglyceride and a method for preparing diglyceride walnut oil by solvent-free enzyme method

Abstract

The application relates to the technical field of oil processing, and discloses a diglyceride preparation device and a method for preparing diglyceride walnut oil by using a solvent-free enzyme method. The device comprises a reaction kettle, a sealing cover, a stirring mechanism and a cage body loaded with immobilized lipase, the cage body is connected to the bottom of the reaction kettle, a cage cover is arranged at the top of the cage body, the cage cover is spliced by a plurality of fan-shaped plate bodies with floating balls, the stirring mechanism generates downward cyclone when being started to open the cage cover, and the cage cover is reset and closed after being closed; a temperature control cavity and a temperature control pipe are arranged on the side wall of the reaction kettle, and an air exhaust pipe is arranged on the sealing cover. In the method, the device is used to put walnut oil, immobilized lipase and glycerol into the reaction kettle, and the stirring reaction is carried out under the condition that the vacuum degree is-0.05 MPa to-0.10 MPa and the temperature is 35-75 DEG C for 10-40 hours, the cage cover is automatically closed after the reaction is completed, the cage body is taken out as a whole, and the lipase can be recovered. The application realizes in-situ rapid recovery of immobilized enzyme, has simple structure and convenient operation, and is suitable for large-scale preparation of functional diglyceride.

Description

Technical Field

[0001] This invention belongs to the field of oil processing technology, specifically relating to a diglyceride preparation apparatus and a solvent-free enzymatic method for preparing diglyceride walnut oil. Background Technology

[0002] Diacylglycerol (DAG) is a functional structural lipid found in very small amounts in natural oils and fats. It possesses physiological functions such as inhibiting weight gain and lowering postprandial blood lipids, and has been approved by many countries for use as a new food ingredient in the food industry. Preparing functional oils rich in diacylglycerol from vegetable oils and glycerol via lipase-catalyzed transesterification is currently one of the mainstream technological routes in this field.

[0003] Free lipases face bottlenecks in industrial applications, including poor stability, difficulty in separation and recovery from reaction systems, and poor reusability, leading to significantly increased production costs. To address these challenges, enzyme immobilization technology has emerged. Immobilizing lipases on suitable carriers not only significantly improves enzyme stability and operational stability but also enables enzyme recovery and reuse, reducing production costs. Immobilized lipases are therefore widely used in the enzymatic synthesis of diglycerides.

[0004] However, while immobilized enzyme technology brings convenience, it also introduces new problems—how to efficiently recover the immobilized enzyme from the reaction system after the reaction is completed.

[0005] Currently, the mainstream methods for industrial recovery of immobilized enzymes are filtration and centrifugation. For example, some technologies use hot filtration to recover lipase after the reaction; others use centrifugation to remove lipase. While these methods can achieve enzyme recovery, they all have significant drawbacks:

[0006] Firstly, both filtration and centrifugation require separating the enzyme catalyst from the large amount of reaction products, making the process cumbersome. After the reaction is complete, the entire reaction system needs to be transferred to filtration or centrifugation equipment, increasing the number of process steps and operating time.

[0007] Secondly, the pressure during filtration and the shear force during centrifugation can cause mechanical damage to the immobilized enzyme particles, affecting the number of times the enzyme can be reused and its catalytic activity. At the same time, residues and losses during the transfer process also reduce the enzyme recovery rate.

[0008] Third, the above operations make it difficult to achieve in-situ enzyme recovery—the enzyme needs to be transferred out of the reactor for separation, which increases the chance of the enzyme coming into contact with air and impurities, and may accelerate enzyme inactivation, especially under high temperature conditions.

[0009] In view of this, the inventor conducted in-depth research on the aforementioned deficiencies in the prior art, which led to the creation of this case. Summary of the Invention

[0010] The purpose of this invention is to provide a diglyceride preparation apparatus and a solvent-free enzymatic method for preparing diglyceride walnut oil, so as to solve the technical problems of cumbersome operation, large enzyme loss, and inability to achieve in-situ recovery of immobilized lipase in the prior art.

[0011] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0012] A diglyceride preparation apparatus includes a reaction vessel, a sealing cover, and a stirring mechanism, and further includes a cage containing immobilized lipase. The cage is detachably connected to the bottom of the reaction vessel, and its side and bottom walls have a plurality of filter holes. The top of the cage is also provided with a cage cover. When the stirring mechanism is started, it generates a downward swirling flow that can open the cage cover. When the stirring mechanism is turned off, the cage cover can be reset to close the cage. A temperature control chamber is also formed in the side wall of the reaction vessel, and a temperature control tube is provided in the temperature control chamber. The two ends of the temperature control tube extend to the outside of the reaction vessel to form a medium inlet and a medium outlet, respectively. The medium inlet and the medium outlet are connected to an external constant temperature circulation device through pipelines. The sealing cover is also provided with a vacuum pipe, which is connected to an external vacuum generator.

[0013] Furthermore, the cage cover is composed of multiple sector-shaped plates, each of which is hinged to the cage body. A float is also provided at the bottom of each sector-shaped plate, near its free end. This structure requires no external power or control signal to achieve adaptive opening and closing of the cage cover according to the stirring state, exhibiting a simple structure and high reliability.

[0014] Furthermore, the top of the cage is provided with multiple limiting components that respectively limit the position of the sector-shaped plate; each limiting component includes a limiting plate and a rotating shaft rotatably connected to the top of the cage, and the rotating shaft is also provided with a knob. The angle position of the limiting plate can be easily adjusted by the knob to adapt to the opening and closing requirements under different working conditions, thereby improving the adaptability and ease of operation of the device.

[0015] Furthermore, the bottom of the reactor vessel is provided with a support base for mounting the cage, and the bottom of the cage is provided with a connecting seat that mates with the support base. The support base includes a support column fixedly connected to the bottom wall of the reactor vessel, a support ring located above the support column, and multiple support rods connecting the support column and the support ring. The connecting seat includes a connecting ring fixedly connected to the bottom of the cage and multiple snap-fit ​​assemblies mounted on the inner wall of the connecting ring, with the multiple snap-fit ​​assemblies arranged in an array along the circumferential direction. The support column, support ring, and support rods constitute a stable support frame, and the connecting ring and snap-fit ​​assemblies enable quick connection and separation between the cage and the support base, ensuring the stable fixation of the cage during operation and providing a structural basis for the rapid assembly and disassembly of the cage.

[0016] Furthermore, the outer wall of the support ring is adapted to the inner wall of the connecting ring; the outer diameter of the support ring gradually increases from top to bottom, and the inner diameter of the connecting ring gradually increases from top to bottom; multiple mounting holes for installing the snap-fit ​​assembly are also formed on the inner wall of the connecting ring, and the snap-fit ​​assembly includes a snap-fit ​​post slidably installed in the mounting hole and a return spring fixedly connected between the bottom of the snap-fit ​​post and the bottom of the mounting hole; the top of the snap-fit ​​post is a hemispherical structure, and multiple snap-fit ​​grooves that mate with the snap-fit ​​post are formed on the outer wall of the support ring, and the snap-fit ​​grooves are adapted to the top of the snap-fit ​​post. The support post, support ring, and support rod constitute a stable support frame, and the connecting ring and snap-fit ​​assembly enable quick connection and separation of the cage and the support base, which not only ensures the stable fixation of the cage during operation, but also provides a structural basis for the quick assembly and disassembly of the cage. In addition, the combination of the two ensures both the stability of the working state and the convenience of disassembly.

[0017] Furthermore, the stirring mechanism includes a stirring shaft rotatably mounted at the bottom of the sealing cover, multiple stirring blades fixedly connected to the stirring shaft, and a motor fixedly connected to the top of the sealing cover. The output shaft of the motor is drively connected to the stirring shaft. The end of the stirring shaft is provided with a downward-pointing conical head, and the stirring blades are fixedly connected to the conical head. The conical head structure creates a smoothly transitioned conical surface at the end of the stirring shaft, which helps reduce stirring resistance and guides the liquid flow downwards, enhancing the downward swirling effect, thereby more effectively opening the cover and promoting the circulation and mixing of the reaction liquid. Simultaneously, the conical head structure reduces the stirring dead zone and improves stirring efficiency.

[0018] Furthermore, the sealing cap is hinged to the reaction vessel, and a sealing gasket is provided at the top of the reaction vessel; the sealing cap is provided with a first feed pipe and a second feed pipe; a discharge pipe is provided at the bottom of the reaction vessel, and support feet are also provided on the side wall of the reaction vessel. This technical solution achieves convenient opening and closing and reliable sealing of the reaction vessel through the hinged sealing cap and sealing gasket; the first and second feed pipes can be used for independent feeding of walnut oil and glycerin respectively, avoiding premature mixing of materials during the feeding process; the discharge pipe is located at the bottom, which is conducive to the complete discharge of reaction products; and the support feet provide stable support for the reaction vessel.

[0019] A solvent-free enzymatic method for preparing diglyceride walnut oil, the method being as follows: 100 parts by weight of walnut oil, 0.5-10 parts by weight of immobilized lipase, and 0.5-15 parts by weight of glycerol are added to the apparatus. After addition, the reaction system is subjected to vacuum treatment, maintaining the vacuum degree between (-0.05) MPa and (-0.10) MPa. The reaction temperature is 35-75℃, the stirring rate is 50-300 r / min, and the reaction time is 10-40 hours. After the reaction is completed, the mixture is filtered while hot to recover the lipase and obtain diglyceride.

[0020] Furthermore, the immobilized lipase is selected from at least one of the following: Lipozyme RM IM, Lipozyme TL IM, and Novozyme 435 immobilized lipase.

[0021] Furthermore, the prepared diglycerides were further refined. Specifically, the diglycerides were added to a decolorizing agent while hot for adsorption and decolorization, followed by filtration to obtain refined walnut diglyceride oil. The decolorizing agent was food-grade activated carbon and activated clay, accounting for 0.5-3.0% of the oil mass, with a mass ratio of activated carbon to activated clay of 1:5-20.

[0022] With the above-described structure, the diglyceride preparation apparatus and solvent-free enzymatic method for preparing diglyceride walnut oil disclosed in this invention have the following advantages compared with the prior art:

[0023] 1. This invention involves loading immobilized lipase into a detachable cage, which is installed at the bottom of the reactor via a quick-release connection. After the reaction, the cage lid automatically closes, locking the enzyme particles inside. Operators simply need to open the sealing cap and loosen the quick-release connection to remove the entire cage from the reactor without transferring the reaction solution to filtration or centrifugation equipment, or performing enzyme filtration or centrifugation. The enzyme particles remain within the cage and can be directly used for the next batch of reaction, achieving in-situ enzyme recovery, significantly simplifying the operation process, and substantially reducing enzyme mechanical loss and activity loss.

[0024] 2. This invention utilizes the opposing forces of buoyancy from a float and the downward swirling impact force generated by stirring to control the opening and closing of the cage lid—when stirring stops, buoyancy prevails, and the lid automatically closes; when stirring starts, the swirling impact force prevails, and the lid automatically opens. This mechanism requires no electrical, pneumatic, or magnetic control signals, no sensors, or actuators; it relies entirely on fluid mechanics and buoyancy principles to achieve adaptive control. It is simple in structure, highly reliable, and low in cost, making it particularly suitable for biocatalytic reactions in a vacuum environment.

[0025] 3. The downward swirling flow generated by the stirring mechanism forces the reaction solution to enter from the top of the cage, pass through the enzyme layer, and flow out from the bottom and side walls, achieving efficient contact between the reaction solution and the immobilized enzyme. Simultaneously, the stirring rate is controlled within a low shear range of 50–300 r / min, and combined with the airfoil impeller design, effectively avoids mechanical damage to the immobilized enzyme particles, protecting the enzyme's activity and lifespan.

[0026] 4. The cage body of this invention achieves rapid assembly and disassembly of the reactor bottom through a combination of a conical guide gap fit and a snap-fit ​​assembly. During installation, the cage body automatically slides down and centers along the conical surface under its own weight, and the snap-fit ​​assembly automatically locks in place. During disassembly, simply pull the cage body upwards, and the hemispherical head locking post automatically disengages and unlocks under the action of the inclined surface. The entire assembly and disassembly process requires no tools and can be completed by a single person within 1 minute, greatly improving the operational efficiency of enzyme replacement and recovery. Attached Figure Description

[0027] The present invention can be further illustrated by the non-limiting embodiments given in the accompanying drawings;

[0028] Figure 1 This is a schematic diagram of the structure of the present invention;

[0029] Figure 2 for Figure 1 A cross-sectional schematic diagram;

[0030] Figure 3 This is a schematic diagram of the structure of the sealing cap of the present invention when it is opened;

[0031] Figure 4 This is a schematic diagram of the cage structure in this invention;

[0032] Figure 5 for Figure 4 A schematic diagram of the decomposition process;

[0033] Figure 6 This is a schematic diagram of the temperature control tube in this invention;

[0034] Figure 7 for Figure 2 A magnified schematic diagram of the local structure at point A;

[0035] Figure 8 for Figure 2 A magnified schematic diagram of the local structure at point B;

[0036] Figure 9 for Figure 5 A magnified schematic diagram of the structure at point C.

[0037] The symbols of the main components are explained as follows: reactor 1, temperature control chamber 11, support base 12, support column 121, support ring 122, snap-fit ​​groove 1221, support rod 123, discharge pipe 13, support foot 14;

[0038] 2. Sealing cap; 21. Air extraction pipe; 22. First feed pipe; 23. Second feed pipe;

[0039] 3. Stirring mechanism; 31. Stirring shaft; 311. Conical head; 32. Stirring blade; 33. Motor.

[0040] Cage body 4, filter hole 41, cage cover 42, fan-shaped plate 421, float 422, limiting component 43, limiting plate 431, rotating shaft 432, knob 433, connecting seat 44, connecting ring 441, mounting hole 4411, buckle assembly 442, snap-fit ​​post 4421, return spring 4422;

[0041] Temperature control tube 5, medium inlet 51, medium outlet 52;

[0042] 6. Sealing gasket. Detailed Implementation

[0043] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that similar or identical parts are referred to by the same reference numerals in the drawings or description. Implementations not shown or described in the drawings are forms known to those skilled in the art. In addition, directional terms mentioned in the embodiments, such as "up," "down," "top," "bottom," "left," "right," "front," and "back," are only for reference to the directions in the drawings and are not intended to limit the scope of protection of the present invention.

[0044] Example 1

[0045] like Figures 1-9As shown, this invention relates to a diglyceride preparation apparatus, comprising a reaction vessel 1, a sealing cover 2, and a stirring mechanism 3, and further comprising a cage 4 containing immobilized lipase. The cage 4 is detachably connected to the bottom of the reaction vessel 1. The side walls and bottom walls of the cage 4 have a plurality of filter holes 41, and the top of the cage 4 is also provided with a cage cover 42. When the stirring mechanism 3 is activated, it generates a downward swirling flow that can open the cage cover 42. After the stirring mechanism 3 is closed, the cage cover 42 can be reset to close the cage 4. A temperature control chamber 11 is also formed in the side wall of the reaction vessel 1. The temperature control chamber 11 is provided with a temperature control tube 5. The two ends of the temperature control tube 5 extend to the outside of the reaction vessel 1, forming a medium inlet 51 and a medium outlet 52, respectively. The medium inlet 51 and the medium outlet 52 are connected to an external constant temperature circulation device through pipelines. A vacuum pipe 21 is also provided on the sealing cover 2, and the vacuum pipe 21 is connected to an external vacuum generator.

[0046] Specifically, the reactor 1 is a vertical cylindrical structure, closed at the bottom and open at the top. An annular temperature control chamber 11 is formed in the side wall of the reactor 1, and a temperature control tube 5 is installed in the temperature control chamber 11. The temperature control tube 5 is arranged in an S-shape around the side wall of the reactor 1 within the temperature control chamber 11 to increase the heat exchange area. The two ends of the temperature control tube 5 extend to the outside of the reactor 1, forming a medium inlet 51 and a medium outlet 52, respectively. The medium inlet 51 and the medium outlet 52 are connected to an external constant temperature circulation device (such as a constant temperature water bath, oil bath, or integrated refrigeration and heating circulation machine) via pipelines. During the reaction, the circulating medium (water or heat transfer oil) circulates between the constant temperature circulation device and the temperature control tube 5, exchanging heat with the reactants through the temperature control tube 5 in the temperature control chamber 11, thereby controlling the reaction temperature within the set range. A discharge pipe 13 is provided at the bottom of the reactor 1 for discharging the product after the reaction. Support legs 14 are also provided on the side wall of the reactor 1 to support the entire device.

[0047] A sealing cap 2 is mounted on top of the reactor 1, hinged to it. The free end of the sealing cap 2 is snap-fitted to the reactor 1. A sealing gasket 6 is provided on the top of the reactor 1, and the sealing cap 2 achieves a tight seal with the reactor 1 through the sealing gasket 6. A vacuum pipe 21 is provided on the sealing cap 2, which connects to an external vacuum generator (such as a vacuum pump) for evacuating the interior of the reactor 1. The sealing cap 2 also has a first feed pipe 22 and a second feed pipe 23, used for the independent feeding of walnut oil and glycerin, respectively. When the sealing cap 2 is closed on top of the reactor 1, the first feed pipe 22 and the second feed pipe 23 connect to the interior of the reactor 1, allowing for the input of materials.

[0048] The stirring mechanism 3 includes a stirring shaft 31 rotatably mounted at the bottom of the sealing cover 2, multiple stirring blades 32 fixedly connected to the stirring shaft 31, and a motor 33 fixedly connected to the top of the sealing cover 2. The output shaft of the motor 33 passes through the sealing cover 2 and is connected to the stirring shaft 31 via a coupling, driving the stirring shaft 31 to rotate. The lower end of the stirring shaft 31 extends into the reactor 1, and the end of the stirring shaft 31 is provided with a tapered head 311 with its tip pointing downwards. The stirring blades 32 are fixedly connected to the tapered head 311. The stirring blades 32 are preferably axial-flow airfoil stirring blades with a blade inclination angle of 30° to 45° and rounded edges to generate a downward swirling flow during stirring, while reducing shear damage to enzyme particles. When the motor 33 is started, it drives the stirring blades 32 to rotate through the stirring shaft 31, generating a downward swirling flow; when the motor 33 is turned off, the swirling flow disappears.

[0049] A cage 4 is located at the bottom of the reactor 1 and is used to load immobilized lipase. The cage 4 is detachably connected to the bottom of the reactor 1. Specifically, the bottom of the reactor 1 is provided with a support base 12 for mounting the cage 4, and the bottom of the cage 4 is provided with a connecting seat 44 that mates with the support base 12. The support base 12 includes a support column 121 fixedly connected to the inner bottom wall of the reactor 1, a support ring 122 located above the support column 121, and multiple support rods 123 connecting the support column 121 and the support ring 122. The support column 121 is vertically arranged, with its lower end fixed to the center of the inner bottom wall of the reactor 1; the support ring 122 is annular and horizontally arranged above the support column 121; the multiple support rods 123 are evenly distributed circumferentially, connecting the support column 121 and the support ring 122 to form a stable support frame. The connecting seat 44 includes a connecting ring 441 fixedly connected to the bottom of the cage 4 and a plurality of snap fasteners 442 installed on the inner wall of the connecting ring 441, with the plurality of snap fasteners 442 arranged in an array along the circumferential direction.

[0050] The outer wall of the support ring 122 is fitted to the inner wall of the connecting ring 441 with a clearance fit. The outer diameter of the support ring 122 gradually increases from top to bottom (i.e., it has a frustum shape with a smaller top and a larger bottom), and the inner diameter of the connecting ring 441 gradually increases from top to bottom (i.e., it has a conical hole shape with a smaller top and a larger bottom). During installation, the cage 4 is inserted from above, and the conical hole of the connecting ring 441 fits onto the frustum of the support ring 122. Since the taper directions of the two are consistent and they have a clearance fit, the cage 4 automatically slides down the conical surface to the predetermined position by its own weight, achieving precise guidance and centering.

[0051] Additionally, multiple mounting holes 4411 for mounting snap-fit ​​assemblies 442 are formed on the inner wall of the connecting ring 441. The snap-fit ​​assembly 442 includes a snap-fit ​​post 4421 slidably mounted in the mounting hole 4411 and a return spring 4422 fixedly connected between the bottom of the snap-fit ​​post 4421 and the bottom of the mounting hole 4411. The top of the snap-fit ​​post 4421 has a hemispherical structure. Multiple snap-fit ​​grooves 1221 are formed on the outer wall of the support ring 122 to mate with the snap-fit ​​post 4421. The snap-fit ​​grooves 1221 are adapted to the top of the snap-fit ​​post 4421 (i.e., the snap-fit ​​grooves 1221 are arc-shaped grooves corresponding to the hemispherical head).

[0052] During installation, the cage 4 slides down along the conical surface. The hemispherical top of the snap-fit ​​post 4421 on the inner wall of the connecting ring 441 contacts the outer wall of the support ring 122. Under the pressure of the outer wall of the support ring 122, the snap-fit ​​post 4421 overcomes the elastic force of the return spring 4422 and retracts into the mounting hole 4411. When the cage 4 slides to the predetermined position, the snap-fit ​​post 4421 aligns with the snap-fit ​​groove 1221 on the outer wall of the support ring 122. Under the elastic force of the return spring 4422, it automatically pops out and snaps into the snap-fit ​​groove 1221, thus locking the cage 4 to the support base 12. The locking force provided by the snap-fit ​​assembly 442 is a slight locking force, mainly used to prevent the cage 4 from accidentally loosening in a non-vacuum state. During disassembly, simply lift the cage body 4 upwards. The hemispherical head of the locking post 4421 generates a horizontal force under the action of the inclined surface of the locking groove 1221, which overcomes the elastic force of the return spring 4422 and exits the locking groove 1221, allowing the cage body 4 to be easily removed. The entire disassembly and assembly process does not require any tools.

[0053] The cage cover 42 is composed of multiple sector-shaped plates 421 (preferably eight), each sector-shaped plate 421 being hinged to the top of the cage 4. Each sector-shaped plate 421 has a float 422 at its bottom (near the free end), which can be connected to the sector-shaped plate 421 via a flexible steel wire rope. The float 422 is hollow (e.g., a hollow 316L stainless steel ball or a corrosion-resistant polymer ball), capable of generating buoyancy in the liquid. When the reactor 1 is filled with liquid and the stirring mechanism 3 is not activated, the float 422, under the action of buoyancy, pushes the sector-shaped plates 421 upwards, and the sector-shaped plates 421 are assembled into a complete cage cover 42, covering the top of the cage 4. When the stirring mechanism 3 is activated and generates a downward swirling flow, the impact force of the swirling flow overcomes the buoyancy of the float 422, pressing the sector-shaped plates 421 downwards, causing them to flip downwards, and the cage cover 42 opens (e.g., ...). Figure 4As shown, the reaction solution enters the cage 4 from the top and contacts the immobilized enzyme. When the stirring mechanism 3 is turned off, the vortex disappears, the buoyancy of the float 422 becomes dominant again, pushing the sector plate 421 upward to reset, and the cage cover 42 closes again. The top of the cage 4 is also provided with multiple limiting members 43, which are used to limit the position of each sector plate 421. The limiting member 43 includes a limiting plate 431 and a rotating shaft 432 rotatably connected to the top of the cage 4. The rotating shaft 432 is also provided with a knob 433. By rotating the knob 433, the angle position of the limiting plate 431 can be adjusted, thereby limiting the upward rotation angle of the sector plate 421.

[0054] The sidewalls and bottomwalls of the cage 4 are provided with a number of filter holes 41. The pore size of the filter holes 41 is smaller than the particle size of the immobilized lipase particles (for example, when the particle size of the immobilized enzyme particles is about 0.9 mm, the pore size of the filter holes 41 is set to 0.2 to 0.6 mm) to prevent the enzyme particles from leaking out of the cage 4, while allowing the reaction solution to enter and exit freely.

[0055] This embodiment also provides a method for preparing diglyceride walnut oil using the above-mentioned diglyceride preparation device via a solventless enzymatic method. The method is as follows: 3 parts by weight of Rhizopus miltiorrhiza lipase (Lipozyme RM IM) are loaded into cage 4, and cage 4 is installed on support seat 12 at the bottom of reactor 1 via bottom connecting seat. The sealing cover 2 is closed. Then, 100 parts by weight of walnut oil and 5 parts by weight of glycerol are added into reactor 1 through first feed pipe 22 and second feed pipe 23, respectively. After the addition is completed, the reaction system is vacuumed to maintain a vacuum degree of (-0.10) MPa. The reaction temperature is 45℃, the stirring rate is 200 r / min, and the reaction time is 30 hours. After the reaction is completed, the mixture is filtered while hot to recover the lipase and obtain diglyceride. Then, 2 parts by weight of food-grade activated carbon and activated clay (mass ratio of activated carbon to activated clay is 1:9) decolorizing agent are added while hot for adsorption and decolorization. The mixture is then filtered to obtain refined walnut diglyceride oil.

[0056] Example 2

[0057] The difference from Example 1 is that the immobilized lipase was 5 parts.

[0058] Example 3

[0059] The difference from Example 1 is that the immobilized lipase was 5 parts, the glycerol was 8 parts, and the transesterification reaction temperature was 60°C.

[0060] Example 4

[0061] The difference from Example 1 is that the amount of glycerol is 3 parts.

[0062] Example 5

[0063] The difference from Example 1 is that the immobilized lipase was 5 parts and the reaction temperature of the transesterification reaction was 50°C.

[0064] Example 6

[0065] The difference from Example 1 is that the amount of glycerol is 8 parts and the reaction temperature of the transesterification reaction is 60°C.

[0066] Comparative Example 1

[0067] The difference from Example 1 is that the transesterification reaction time is 10 hours.

[0068] Comparative Example 2

[0069] The difference from Example 1 is that the immobilized lipase is 1 part.

[0070] Comparative Example 3

[0071] The difference from Example 1 is that the immobilized lipase was 5 parts, and the reaction system was not vacuumed.

[0072] The specific test results are shown in Table 1.

[0073] Table 1

[0074]

[0075] The test results show that the diglyceride products prepared in the embodiments of the present invention have a purity of ≥40%, and all indicators are better than those of the comparative example.

[0076] Comparative Example 1 showed an incomplete enzyme reaction due to an excessively short reaction time; Comparative Examples 2 and 3 showed insufficient enzyme addition and lack of vacuum conditions, respectively, which affected reaction equilibrium and the forward progression of the product. The results indicate that the synergistic effect of the various technical features of this invention significantly improves the production efficiency and product quality of diglycerides.

[0077] Test results show that the present invention promotes the forward reaction of diglyceride synthesis and improves the conversion rate of triglycerides and the content of target products by optimizing the immobilized lipase, the amount of glycerol added and the corresponding reaction conditions.

[0078] The foregoing has provided a detailed description of the apparatus for preparing diglycerides and the method for preparing diglyceride walnut oil using a solvent-free enzymatic method, as provided by the present invention. The specific embodiments are provided only to aid in understanding the method and core concepts of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A diglyceride preparation apparatus, comprising a reaction vessel (1), a sealing cap (2), and a stirring mechanism (3), characterized in that: It also includes a cage (4) for loading immobilized lipase; the cage (4) is detachably connected to the bottom of the reactor (1), and the side wall and bottom wall of the cage (4) are provided with a number of filter holes (41), and the top of the cage (4) is also provided with a cage cover (42); when the stirring mechanism (3) is started, it generates a downward swirling flow that can open the cage cover (42), and after the stirring mechanism (3) is closed, the cage cover (42) can be reset to close the cage (4); a temperature control chamber (11) is also formed in the side wall of the reactor (1), and a temperature control tube (5) is provided in the temperature control chamber (11). The two ends of the temperature control tube (5) extend to the outside of the reactor (1) to form a medium inlet (51) and a medium outlet (52) respectively. The medium inlet (51) and the medium outlet (52) are connected to an external constant temperature circulation device through pipelines; a vacuum pipe (21) is also provided on the sealing cover (2), and the vacuum pipe (21) is connected to an external vacuum generator.

2. The apparatus for preparing diglycerides according to claim 1, characterized in that: The cage cover (42) is made up of multiple fan-shaped plates (421) spliced ​​together. Each fan-shaped plate (421) is hinged to the cage body (4). The bottom of the fan-shaped plate (421) is also provided with a float (422), which is close to the free end of the fan-shaped plate (421).

3. The diglyceride preparation apparatus according to claim 2, characterized in that: The top of the cage (4) is also provided with a plurality of limiting members (43) that limit the fan-shaped plate (421) respectively; the limiting member (43) includes a limiting plate (431) and a rotating shaft (432) rotatably connected to the top of the cage (4), and the rotating shaft (432) is also provided with a knob (433).

4. The diglyceride preparation apparatus according to claim 1, characterized in that: The bottom of the reactor (1) is also provided with a support base (12) for installing the cage (4), and the bottom of the cage (4) is also provided with a connecting seat (44) that cooperates with the support base (12); the support base (12) includes a support column (121) fixedly connected to the bottom wall of the reactor (1), a support ring (122) located above the support column (121), and multiple support rods (123) connected between the support column (121) and the support ring (122); the connecting seat (44) includes a connecting ring (441) fixedly connected to the bottom of the cage (4) and multiple snap-fit ​​components (442) installed on the inner wall of the connecting ring (441), and the multiple snap-fit ​​components (442) are arranged in an array along the circumferential direction.

5. The diglyceride preparation apparatus according to claim 4, characterized in that: The outer wall of the support ring (122) is adapted to the inner wall of the connecting ring (441); the outer diameter of the support ring (122) gradually increases from top to bottom, and the inner diameter of the connecting ring (441) gradually increases from top to bottom; a plurality of mounting holes (4411) for mounting the buckle assembly (442) are also formed on the inner wall of the connecting ring (441), and the buckle assembly (442) includes a snap-fit ​​post (4421) slidably installed in the mounting hole (4411) and a return spring (4422) fixedly connected between the bottom of the snap-fit ​​post (4421) and the bottom of the mounting hole (4411); the top of the snap-fit ​​post (4421) is a hemispherical structure, and a plurality of snap-fit ​​grooves (1221) that cooperate with the snap-fit ​​post (4421) are formed on the outer wall of the support ring (122), and the snap-fit ​​grooves (1221) are adapted to the top of the snap-fit ​​post (4421).

6. The apparatus for preparing diglycerides according to claim 1, characterized in that: The stirring mechanism (3) includes a stirring shaft (31) rotatably mounted on the bottom of the sealing cover (2), a plurality of stirring blades (32) fixedly connected to the stirring shaft (31), and a motor (33) fixedly connected to the top of the sealing cover (2). The output shaft of the motor (33) is connected to the stirring shaft (31) in a transmission manner. The end of the stirring shaft (31) is provided with a cone head (311) with the tip pointing downwards, and the stirring blades (32) are fixedly connected to the cone head (311).

7. The apparatus for preparing diglycerides according to claim 1, characterized in that: The sealing cover (2) is hinged to the reactor (1), and the top of the reactor (1) is provided with a sealing gasket (6); the sealing cover (2) is provided with a first feed pipe (22) and a second feed pipe (23); the bottom of the reactor (1) is provided with a discharge pipe (13), and the side wall of the reactor (1) is also provided with a support foot (14).

8. A solvent-free enzymatic method for preparing diglyceride walnut oil, characterized in that: The method is as follows: 100 parts by weight of walnut oil, 0.5-10 parts by weight of immobilized lipase, and 0.5-15 parts by weight of glycerol are added... In the apparatus described in any one of claims 1-7, after the input is completed, the reaction system is subjected to vacuum treatment to maintain the vacuum degree between (-0.05) MPa and (-0.10) MPa, the reaction temperature is 35 to 75°C, the stirring rate is 50 to 300 r / min, the reaction time is 10 to 40 hours, and after the reaction is completed, it is filtered while hot to recover the lipase and obtain diglyceride.

9. The method according to claim 8, characterized in that: The immobilized lipase is selected from at least one of the following: *Rhizopus miltiorrhiza* lipase (Lipozyme RM IM), *Thermophilus spp.* lipase (Lipozyme TL IM), and *Candida antarcticis* lipase (Novozyme 435) immobilized lipase.

10. The method according to claim 8, characterized in that: The prepared diglycerides were further refined by adding a decolorizing agent while hot for adsorption and decolorization, followed by filtration to obtain refined walnut diglyceride oil. The decolorizing agent was food-grade activated carbon and activated clay, accounting for 0.5-3.0% of the oil mass, with a mass ratio of activated carbon to activated clay of 1:5-20.

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