A high-content OPO grease mixture and preparation method thereof

Abstract

The present invention provides a high-content OPO oil and fat mixture and a preparation method thereof, which uses specific raw materials for transesterification reaction, and solves the problems of uneven distribution of transesterification lipase sedimentation and insufficient local enzymatic transesterification reaction caused by lateral convection through fine control of temperature. The OPO structured fat prepared by the method further increases the content of OPO and SN-2 palmitic acid, and significantly reduces the content of palmitic acid glyceride, which proposes a new industry standard for OPO structured fat in the food field, and is of great significance.

Description

Technical Field

[0001] The invention relates to the field of fat biosynthesis, in particular to the field of enzyme-catalyzed transesterification of long-chain fatty acids, and more particularly to a high-content OPO oil and fat mixture and a preparation method thereof. Background Art

[0002] 3%-5% of the fat in breast milk is triglycerides (98%-99%) formed by the combination of various fatty acids and glycerol. It not only provides half of the energy required for infants and young children, but also provides them with nutrients such as essential fatty acids and fat-soluble vitamins, which plays an important role in the growth and development of infants and young children. Breast milk fat is a very complex type of fat in nature. There are more than 400 known fatty acids and more than 200 different triglycerides including isomers. Together, they provide comprehensive and balanced nutrition for infants and young children. The triglyceride fatty acids in breast milk mainly include oleic acid (30%-35%), palmitic acid (20%-30%), linoleic acid (7%-14%) and stearic acid (5.7%-8%), of which about 60%-70% of palmitic acid is located at the SN-2 position in the triglyceride backbone structure, while unsaturated fatty acids (including oleic acid, linoleic acid and ω-3 polyunsaturated fatty acids) are mostly located at the SN-1,3 positions in the triglyceride backbone structure. Research results show that triglycerides containing SN-2 palmitic acid can effectively promote calcium ion absorption, increase normal calcium digestion and absorption and bone growth and development in infants and young children in the early stage, make infants and young children form soft feces, and thus reduce the occurrence of constipation. Triglycerides containing SN-2 palmitic acid can also affect the composition of intestinal flora in infants and young children, reduce the level and severity of intestinal inflammation, and improve the crying of infants and young children. It is of great significance to the absorption and metabolism of lipids in infants and young children and their growth and development.

[0003] When a lactating mother cannot produce enough breast milk, infant formula can replace breast milk as the main source of nutrition for infant growth and development. Common fats used in infant formula are vegetable oils or animal fats, especially cow milk fat. Since the composition and distribution of fatty acids in vegetable oils and mammalian milk fat are different from those in breast milk - palmitic acid in vegetable oils is mainly (>80%) at SN-1,3, and the palmitic acid content of animal fats such as milk fat is similar to that of breast milk, but the SN-2 palmitic acid is only about 40%. Therefore, it has become a necessary means to modify vegetable oils, animal fats or oil mixtures to mimic the composition and distribution of fatty acids in human breast milk. This modified fat is a structural fat similar to breast milk fat. Structural fats have been successfully developed and commercialized as energy supplements. They are the main source of essential fatty acids and nutritional fortifiers that are legally allowed to be added to infant formula. It is required that the content of palmitic acid at the SN-2 position accounts for no less than 52% of all palmitic acid, the content of OPO is no less than 40%, and the content of palmitic acid triglyceride (PPP) is less than 10%. OPO nutritional enhancers are only allowed to be produced and supplied using the enzymatic biosynthesis method with lipase for the food industry using edible vegetable oil as raw materials. Due to the variety of reaction raw materials and synthesis methods, the existing biosynthetic OPO content is usually between 40-55%, and the SN-2 palmitic acid content is between 52-67%.

[0004] Chinese invention patent application CN101273118A (published on September 24, 2008) discloses a method for preparing triglycerides, in the presence of 2% by weight of 1,3-specific lipase such as RML (Rhizopus miehei lipase) or RDL (Rhizopus germanica lipase), triolein is reacted with excess stearic acid to obtain 1,3-distearic acid-2-oleic acid glyceride, unconverted triolein and other stearic acid containing glycerides, and then dry-distilled different triglyceride fractions. Among them, the palmitic acid triglyceride fraction is reacted in the presence of 2% 1,3-specific lipase, 50°C and stirring to be converted into OPO. This method requires sufficient refining of the OPO fraction to increase the OPO content, but cannot further reduce the content of palmitic acid triglyceride (less than 8%).

[0005] Chinese invention patent application CN101287819A (published on October 15, 2008) discloses another technical route for OPO, which uses high oleic sunflower oil and alcohols with 1-6 carbon atoms to undergo alcoholysis to obtain 2-oleic triglyceride, which is then acylated with palmitic acid to obtain OPO. The alcoholysis reaction needs to be carried out in an organic solvent, such as acetone; the safety level during production is high and must be completed in an explosion-proof workshop. The above-mentioned small molecule alcohols must be further removed by methods such as reduced pressure distillation. If these substances cannot be effectively removed, it will bring uncertain food safety risks to the growth and development of infants and young children, and cannot meet the quality and food safety requirements of high-content OPO.

[0006] Chinese invention patent application CN102757988A (published on October 31, 2012) discloses a method for preparing 1,3-dioleoyl-2-palmitoylglycerol, which uses glycerol, palmitic acid and oleic acid or oleic acid ester as raw materials for biosynthesis, and also involves the production of OPO using PPP as the main raw material, so the PPP content in the product cannot be effectively controlled. In addition, the technology requires that it be carried out in an organic solvent such as n-hexane, and the residual alcohol still poses a food safety risk.

[0007] Chinese invention patent application CN101679909A (published on March 24, 2010) discloses a method for preparing a glyceride composition, which uses palm oil stearic acid glyceride and sunflower oil as raw materials for random ester exchange reaction, and then conducts an enzymatic ester exchange reaction between the randomly esterified palm oil stearic acid glyceride and oleic acid or its non-glyceride. The technical route is too complicated, resulting in the inability to produce high-content OPO.

[0008] Chinese invention patent application CN104186705A (published on December 10, 2014) discloses a method for synthesizing structured lipids based on enzymatic acidolysis of palmitic acid triglycerides, using perilla seed oil and other raw materials as raw materials, completely hydrolyzing them under solvent conditions such as ethanol to obtain free fatty acids, and then synthesizing structured lipids with palmitic acid triglycerides under lipase conditions, with the palmitic acid content at the SN-2 position being ≥90%. This method completely hydrolyzes the oil in the presence of a solvent and then performs an ester exchange reaction, which has the risk of excessive solvent and high production costs.

[0009] Other Chinese invention patent applications CN109984205A, CN109984211A and CN109984215A all disclose the biosynthesis of OPL and OPO compositions using palm stearate and high oleic sunflower oil as raw materials under lipase catalysis, wherein OPL accounts for more than 25wt% of the composition, the total amount of OPL and OPO accounts for more than 40wt%, and the sn-2 position palmitic acid accounts for more than 55wt% of the total palmitic acid content. The compositions provided by the above methods still find it difficult to meet the requirements for high OPO content.

[0010] On the other hand, PPP content is a key indicator for determining the purity of OPO structural lipids. Currently, no relevant process has been disclosed that can control the PPP content below 1%. Since most processes are based on the process route of enzymatic ester exchange between PPP and oleic acid, it is difficult to effectively reduce the PPP content. Summary of the invention

[0011] Purpose of the invention: The purpose of the present invention is to further optimize the production raw materials and reaction conditions to produce a biosynthetic method of higher-specification 1,3-dioleyl-2-palmitoyl triglyceride (OPO) by a one-step method; another purpose of the present invention is to provide a higher-specification OPO oil mixture produced by the aforementioned synthesis method, in particular to provide an OPO oil mixture with a palmitic triglyceride content controlled to below 1%.

[0012] In order to achieve the above-mentioned invention object, the present invention provides a biosynthesis method of a high-content OPO oil mixture, comprising: mixing palm stearin with a melting point of 55-65°C and a long-chain fatty acid with an oleic acid content of 70-90 wt% in a mass ratio of 1:(4-10), adding the mixture to a reaction system containing immobilized transesterification lipase, and maintaining the mixture at a first temperature; introducing an inert gas into the reaction system in a continuous bubbling or intermittent bubbling manner, and continuously reacting for 84-108 hours to obtain a primary product; the difference between the highest local temperature and the lowest local temperature in the reaction system does not exceed 2°C; and subjecting the primary product to deacidification, decolorization, and deodorization treatment to obtain 1,3-dioleyl-2-palmitoylglycerol.

[0013] The present invention uses palm stearate with a melting point of 55-65 ° C as the starting material to produce OPO, which has a higher melting point than traditional palm stearate. Palm stearate is obtained by refining and fractionating palm oil, wherein the fatty acids are mainly C16:0, as well as other fatty acids such as C18:0, C18:1, C18:2, and also fatty acid triglycerides such as PPP, POP, and OPO. Compared with traditional palm stearate, high melting point palm stearate has more times of fractionation to make PPP higher in purity, so SN-2 palmitic acid accounts for a higher proportion of total palmitic acid content, and has the characteristic of being more favorable for improving the SN-2 content of the reaction product. However, the melting point of palm stearate exceeds 60 ° C, resulting in too high a reaction temperature, which will affect the activity of lipase and the number of uses, causing a decrease in OPO content and an increase in cost. As a further optimization of the present invention, the melting point of the palm stearate is 59-62 ° C, and more preferably, the melting point of the palm stearate is 60 ° C. On the other hand, palm stearyl ester at this melting point is particularly suitable for transesterification with oleic acid in a reaction system containing immobilized transesterification lipase at the first temperature. Under the action of continuous turbulence, the oil mixture and the immobilized transesterification lipase in the reaction system are evenly distributed and will not agglomerate, thereby further increasing the content of palmitic acid at the SN-2 position.

[0014] On the other hand, the present invention uses a higher content of oleic acid and an excess of long-chain fatty acids for reaction, and further increases the OPO content and SN-2 palmitic acid. Compared with oleic acid hydrolyzed with ordinary vegetable oil and high oleic acid vegetable oil, the present invention has a higher oleic acid content, which is more conducive to oleic acid replacing palmitic acid to synthesize OPO. As a further optimization of the present invention, the long-chain fatty acids contain 80-90 wt% of oleic acid, which results in a greatly increased probability of high-purity oleic acid replacing palmitic acid, and the excess oleic acid completely reacts with the limited PPP, which not only increases the OPO content, but also effectively reduces the impurity PPP content.

[0015] The continuous reaction of the present invention is carried out in a closed reaction vessel, wherein the reaction vessel is provided with at least an immobilized transesterification lipase reaction column, at least one raw material feed port and a product discharge port, and the enzyme catalytic reaction is carried out simultaneously with the feeding and discharging of the materials. Specifically, the continuous reaction is to fix the immobilized transesterification lipase in the biosynthesis reaction column, and the fresh reaction raw materials enter from the upper part of the reaction column, continuously react with the lipase, and discharge the reaction products from the lower part. This continuous production process effectively reduces the storage of reaction raw materials and products and the energy consumption of heating and cooling, greatly reduces production costs and improves production efficiency.

[0016] The inventors found that in the actual production of OPO, the difference in local temperature will lead to lateral convection in the reaction system. The lateral convection caused by this continuous temperature difference will cause the immobilized transesterification lipase to coagulate, affecting the efficiency of the transesterification reaction. On the other hand, although stirring, jetting and the like can form a large shear force locally, which is beneficial to improving the uniformity of the reaction system, local coagulation will also occur in other areas. The inventors reduced or even eliminated the lateral convection by controlling the local temperature difference, and the OPO content and SN-2 palmitic acid content in the produced OPO oil and fat mixture were unexpectedly significantly improved. By adding specific fat-soluble pigments to the raw materials, the lateral convection was observed to be significantly improved, indicating that controlling the local temperature is one of the key measures to avoid lateral convection. Although the technical means of local temperature control is not complicated to implement, it is difficult for those skilled in the art to further obtain OPO structure ester products with higher purity and quality based on the existing technology (especially OPO structure esters that simultaneously meet the requirements of 1,3-dioleoyl-2-palmitoyl triglyceride content ≥ 60wt%, SN-2 palmitic acid content ≥ 70wt% of total palmitic acid content, and palmitic acid triglyceride content ≤ 1wt%). The inventors found that, compared with improving the fluid disturbance mode and improving the shear force of the fluid during stirring, the use of refined temperature control can more efficiently control the lateral convection of the reaction system, which is a problem that those skilled in the art tend to overlook when exploring solutions to the problem. As an optional embodiment, the present invention introduces an inert gas at the same temperature as the first temperature for reaction, and the first temperature is 60±1°C.

[0017] Furthermore, the immobilized transesterification lipase of the present invention is from any one or a combination of Rhizomucor miehei lipase RML or Rhizopus delemar lipase RDL, including but not limited to. Rhizomucor miehei lipase RML is preferably used. The immobilization method includes but is not limited to cross-linking, embedding, adsorption, and a method of combining with other carriers. The Rhizomucor miehei lipase RML can be from a commercially available product, such as Lipase 7000 pro from Weilan Biotechnology. TM 、Lipozym RM IM from Novozymes of Denmark ® , and mutant strains with improved properties can also be obtained through genetic engineering for production. Preferably, the optimal activity temperature of the immobilized transesterification lipase provided by the present invention should be at least greater than or equal to the first temperature, preferably, 0.1-5.0°C higher than the first temperature, so as to increase the number of times the immobilized enzyme can be reused without significantly reducing the enzyme activity.

[0018] It should be understood that in actual production, it is often difficult to control the difference between the highest local temperature and the lowest local temperature of the reaction system within 2 °C, especially for the reaction system for industrial production of OPO (for example, 100L, 300L and above). The heat source of the reaction equipment often comes from the outer wall or bottom of the container, and there is a large difference between the central temperature and the peripheral temperature of the reaction equipment. The reaction system provided by the present invention includes at least one first temperature sensor that can detect the lowest local temperature, and a second temperature sensor that can detect the highest local temperature. At the same time, the reaction system also includes a heating device for adjusting the lowest local temperature. Therefore, the synthesis method described in the present application also includes a temperature acquisition and temperature difference control method of the reaction system, specifically including:

[0019] S1: collecting the lowest local temperature and the highest local temperature of the reaction system in real time;

[0020] S2: Calculate the difference between the lowest local temperature and the highest local temperature, and when the difference is higher than a set threshold, execute step S3;

[0021] S3: Start the heating device to make the lowest local temperature equal to the highest local temperature.

[0022] As a preferred embodiment of the present invention, the heating device is arranged at a position with the lowest local temperature in the reaction system. For example, for a reaction device using water jacket heating, the heating device is preferably arranged at the center of the reaction device. More preferably, the heating device has a continuous heat exchange contact surface extending in a vertical direction.

[0023] To this end, the reaction equipment also includes at least one controller, which receives signals sent by the first temperature sensor and the second temperature sensor, and converts the calculated difference between the lowest local temperature and the highest local temperature into a control signal. When the difference between the lowest local temperature and the highest local temperature is greater than 0, the heating device is started; when the difference between the lowest local temperature and the highest local temperature is less than or equal to 0, the heating device is stopped.

[0024] Furthermore, in order to provide the function of bubbling or intermittent bubbling, the bottom of the reaction device is also provided with an air inlet for providing bubbling, and those skilled in the art can make improvements based on the existing technology according to actual needs.

[0025] The OPO oil mixture prepared by the above-mentioned synthesis method in the present invention has the following characteristics:

[0026] Palmitic acid triglyceride content ≤ 1 wt%;

[0027] 1,3-dioleyl-2-palmitoyl triglyceride content ≥ 60 wt%; and

[0028] The SN-2 palmitic acid content accounts for ≥70 wt% of the total palmitic acid content.

[0029] As a preferred embodiment of the present invention, the OPO grease mixture has the following characteristics:

[0030] Palmitic acid triglyceride content ≤ 0.7 wt%;

[0031] 1,3-dioleyl-2-palmitoyl triglyceride content ≥ 60 wt%; and

[0032] The SN-2 palmitic acid content accounts for ≥70 wt% of the total palmitic acid content.

[0033] In summary, the biosynthesis method of a high-content OPO oil mixture provided by the present invention utilizes specific raw materials for transesterification reaction, and solves the problems of uneven distribution of transesterification lipase sedimentation and insufficient local enzymatic transesterification reaction caused by lateral convection through refined control of temperature. The melting point of palm stearic acid is adapted to the first temperature of the reaction system. After the molten palm stearic acid and oleic acid are mixed, they are fully contacted with lipase to start the biosynthesis reaction, that is, the oil mixture is closely surrounded by the immobilized lipase carrier, and the lipase carrier is flowed and collided by bubbling, which ensures that the oil and lipase are fully contacted and reacted, and the reaction products are dispersed and overflowed from around the lipase carrier, and new reaction oil raw materials fill the space left by the reaction products to continue the cycle reaction. And the first temperature is more conducive to ensuring the life of the immobilized enzyme, avoiding the generation of undesirable coked materials due to excessively high temperature, and improving the efficiency and quality of industrially produced products as a whole.

[0034] It is worth noting that the raw materials of the present application contain palm stearate with a higher PPP content and a melting point of 55-65°C, which poses a new challenge for controlling the palmitic acid triglyceride content below 1 wt%. The present application solves this challenge by combining enzyme catalysis with long-chain fatty acids with high oleic acid content in excess supply, bubbling ventilation, continuous reaction and other means, especially through refined temperature control, and further controls the palmitic acid triglyceride content to no more than 0.7wt%. This technical effect is unexpected.

[0035] The method provided by the present invention proposes a new industry standard for the current OPO structured lipids, and in particular, provides a high-quality OPO structured lipid with "no detection" of PPP. According to the "National Standard of the People's Republic of China GB 30604-2015", for the food nutrition enhancer 1,3-dioleoyl-2-palmitoyl triglyceride (OPO) prepared by ester exchange catalyzed by lipase for food industry with vegetable oil and oleic acid as raw materials, it should at least meet the requirements of OPO content ≥40%, SN-2 palmitic acid accounting for ≥52% of the total palmitic acid content, and palmitic acid triglyceride (PPP) content <10%. High-content PPP will continuously release palmitic acid in infants and children and combine with calcium to form calcium soaps to cause constipation, greatly affecting the effect of OPO as a functional lipid. Those skilled in the art mainly explore how to increase the OPO content and the SN-2 palmitic acid content, but there are few related technologies to significantly reduce the PPP content. Among them, the conventional method of producing OPO by random ester exchange using triglycerides as the starting point of synthesis cannot guarantee precise temperature control and high-purity reaction raw materials, thus causing excessive PPP to remain in the reaction system, and the subsequent refining process cannot significantly reduce the PPP content. This application limits the PPP content to below 0.7% by controlling the raw materials and reaction temperature, which is of great significance in the field of structural lipids.

[0036] Technical terms and abbreviations used in this application

[0037] Unless otherwise specified, the three-letter abbreviations formed by the combination of O, P, L, and N in the present invention all represent: fatty acid (acyl) glycerides formed by esterification reaction with any identical or different saturated / unsaturated fatty acids at a single site or multiple sites of triglyceride as a backbone, wherein P represents a palmitic acid residue, O represents an oleic acid residue, L represents a linoleic acid residue, and N represents that no esterification reaction has occurred.

[0038] OPO: 1,3-dioleyl-2-palmitoylglycerol;

[0039] POP: 1,3-dipalmitoyl-2-oleylglycerol;

[0040] OPL: 1-oleoyl-2-palmitoyl-3-linoleylglycerol;

[0041] PPL: 1,2-dipalmitoyl-3-linoleylglycerol;

[0042] PPP: palmitic acid glyceryl, or palmitic acid triglyceride, or tripalmitin. DETAILED DESCRIPTION

[0043] The present invention is further described below in conjunction with specific examples. Unless otherwise specified, all percentages, parts and ratios are by weight.

[0044] Example 1

[0045] This embodiment uses a 100L jacketed enzyme bioreactor to produce a high-content OPO oil mixture. The reactor has a hollow cylindrical reaction chamber, and the outer shell is made of food-grade 304 stainless steel with a water bath jacket (diameter-to-height ratio 1:1.5) to heat the reactor from the periphery. The head is provided with a feed port, a nitrogen interface, a vent, a pressure gauge, a window, a flange and other structures; the bottom is provided with a discharge port, a slag discharge port, a bubble generator, a valve and the like. A first temperature sensor for detecting the lowest local temperature is provided at the center of the reaction chamber; a second temperature sensor for detecting the highest local temperature is provided near the jacket of the reaction chamber. A distributor is provided in the reaction chamber, and a heating device for adjusting the lowest local temperature is fixed thereto. The heating device is arranged at a position with the lowest local temperature in the reaction system. This embodiment and the remaining embodiments below are preferably arranged at the center of the reaction equipment, and the heating device has a continuous heat exchange contact surface extending in a vertical direction. The first temperature sensor, the second temperature sensor and the heating device are all powered by a power supply and electrically connected to the controller. It should be understood that for other possible situations, such as a reaction system under larger-scale production, multiple heating devices may be required to balance the lowest local temperature and the highest local temperature in the reaction system. In this case, in addition to being configured in the center, multiple heating devices should also be configured centrally and symmetrically between the periphery and the center. Those skilled in the art can make adaptive adjustments according to the requirements of the temperature difference control of this embodiment, all within the scope of protection of this application.

[0046] (1) Palm stearyl ester with a melting point of 55-65°C and long-chain fatty acids with an oleic acid content of 70-90 wt % are mixed in a mass ratio of 1:6 to obtain a fat mixture, which is heated to 59-61°C and kept warm for use after being uniformly stabilized.

[0047] (2) Adding immobilized transesterification lipase (Rhizomucor miehei lipase RML, purchased from Qingdao Weilan Biotechnology Group Co., Ltd.) and the oil mixture into the reaction chamber, so that the immobilized transesterification lipase and the oil mixture can fully contact and react.

[0048] (3) Raise the temperature of the reactor jacket to 59-61 °C and maintain it at that temperature. Pump food-grade nitrogen at 59-61 °C into the reaction system continuously through a bubbler for 10-60 min.

[0049] (4) Cover the head and continuously pump the oil and fat mixture into the reaction vessel using a piston pump. Control the flow rate of the reaction product to be 45±2 kg / h. Continue the reaction for 84-108 h to obtain the primary product.

[0050] (5) The primary product is subjected to deacidification, decolorization and deodorization treatment to obtain 1,3-dioleyl-2-palmitoylglycerol.

[0051] In the continuous reaction process, the temperature collection and temperature difference control method of the reaction system are also included, specifically including:

[0052] S1: real-time collection of the lowest local temperature and the highest local temperature of the reaction system;

[0053] S2: Calculate the difference between the lowest local temperature and the highest local temperature. When the difference is higher than a set threshold, execute step S3;

[0054] S3: Start the heating device to make the lowest local temperature equal to the highest local temperature.

[0055] The controller receives signals sent by the first temperature sensor and the second temperature sensor, and converts the calculated difference between the lowest local temperature and the highest local temperature into a control signal. When the difference between the lowest local temperature and the highest local temperature is greater than 0, the heating device is started; when the difference between the lowest local temperature and the highest local temperature is less than or equal to 0, the heating device is stopped.

[0056] Among them, the deacidification process mainly includes molecular distillation, alkali refining and water washing, and the acid value is limited to no more than 3 mg KOH / g. The decolorization process mainly includes filtering after adding acidic white clay and activated carbon. The deodorization process mainly includes low-temperature deodorization tower treatment, and the peroxide value is no more than 0.75 mmol / kg.

[0057] Optionally, in addition to the above-mentioned processes, this embodiment may further include processes such as microporous membrane filtration.

[0058] The OPO oil mixture prepared by the above method also has the following characteristics:

[0059] ① Palmitic acid triglyceride content ≤ 1 wt%;

[0060] ② 1,3-dioleyl-2-palmitoyl triglyceride content ≥ 60 wt%; and

[0061] ③ The palmitic acid at the SN-2 position accounts for ≥70 wt% of the total palmitic acid content.

[0062] Among them, the detection method of 1,3-dioleoyl-2-palmitoyl triglyceride (OPO) refers to the contents recorded in A.3 of Appendix A of "National Standard of the People's Republic of China GB 30604-2015"; the detection method of SN-2 palmitic acid as a percentage of total palmitic acid content refers to the contents recorded in A.3 of Appendix A of "National Standard of the People's Republic of China GB 30604-2015"; the detection method of palmitic acid triglyceride (PPP) refers to the contents recorded in A.3 of Appendix A of "National Standard of the People's Republic of China GB 30604-2015".

[0063] Example 2

[0064] This example provides a preferred method for preparing an OPO oil mixture based on Example 1. The method uses the same jacketed enzyme bioreactor as Example 1 and specifically includes the following steps:

[0065] (1) Palm stearyl ester (iodine value 12) with a melting point of 60°C and a long-chain fatty acid with an oleic acid content of 90 wt% were mixed in a mass ratio of 1:6 to obtain a fat mixture, which was heated to 60°C and kept warm for use after being uniformly stabilized.

[0066] (2) The reaction chamber was filled with immobilized transesterification lipase (purchased from Qingdao Weilan Biotechnology Group Co., Ltd.) to completely soak the oil and fat mixture.

[0067] (3) Raise the temperature of the reactor jacket to 60 °C and maintain it at that temperature. Pump 60 °C food-grade nitrogen into the reaction system through a bubbler and continue bubbling for 30 min.

[0068] (4) Cover the head and continuously pump the oil and fat mixture into the reaction vessel using a piston pump. Control the flow rate of the reaction product to be 45±2 kg / h. Continue the reaction for 84-108 h to obtain the primary product.

[0069] (5) The primary product is subjected to deacidification, decolorization and deodorization treatment to obtain 1,3-dioleyl-2-palmitoylglycerol.

[0070] Example 3

[0071] This example provides a preferred method for preparing an OPO oil mixture based on Example 1. The method uses the same jacketed enzyme bioreactor as Example 1 and specifically includes the following steps:

[0072] (1) Palm stearyl ester (iodine value 12) with a melting point of 60°C and a long-chain fatty acid with an oleic acid content of 90 wt% were mixed in a mass ratio of 1:5 to obtain a fat mixture, which was heated to 60°C and kept warm for use after being uniformly stabilized.

[0073] (2) The reaction chamber was filled with immobilized transesterification lipase (purchased from Qingdao Weilan Biotechnology Group Co., Ltd.) to completely soak the oil and fat mixture.

[0074] (3) Raise the temperature of the reactor jacket to 60 °C and maintain it at that temperature. Pump 60 °C food-grade nitrogen into the reaction system through a bubbler and continue bubbling for 30 min.

[0075] (4) Cover the head and continuously pump the oil and fat mixture into the reaction vessel using a piston pump. Control the flow rate of the reaction product to be 45±2 kg / h. Continue the reaction for 84-108 h to obtain the primary product.

[0076] (5) The primary product is subjected to deacidification, decolorization and deodorization treatment to obtain 1,3-dioleyl-2-palmitoylglycerol.

[0077] Example 4

[0078] This example provides a preferred method for preparing an OPO oil mixture based on Example 1. The method uses the same jacketed enzyme bioreactor as Example 1 and specifically includes the following steps:

[0079] (1) Palm stearyl ester (iodine value 12) with a melting point of 60 °C and a long-chain fatty acid with an oleic acid content of 90 wt% were mixed in a mass ratio of 1:6 to obtain a fat mixture, which was heated to 58 °C and kept warm for use after being uniformly stabilized.

[0080] (2) The reaction chamber was filled with immobilized transesterification lipase (purchased from Qingdao Weilan Biotechnology Group Co., Ltd.) to completely soak the oil and fat mixture.

[0081] (3) Raise the temperature of the reactor jacket to 60 °C and maintain it at that temperature. Pump 60 °C food-grade nitrogen into the reaction system through a bubbler and continue bubbling for 30 min.

[0082] (4) Cover the head and continuously pump the oil and fat mixture into the reaction vessel using a piston pump. Control the flow rate of the reaction product to be 45±2 kg / h. Continue the reaction for 84-108 h to obtain the primary product.

[0083] (5) The primary product is subjected to deacidification, decolorization and deodorization treatment to obtain 1,3-dioleyl-2-palmitoylglycerol.

[0084] Example 5

[0085] This example provides a preferred method for preparing an OPO oil mixture based on Example 1. The method uses the same jacketed enzyme bioreactor as Example 1 and specifically includes the following steps:

[0086] (1) Palm stearyl ester (iodine value 24) with a melting point of 55°C and a long-chain fatty acid with an oleic acid content of 90 wt% were mixed in a mass ratio of 1:6 to obtain a fat mixture, which was heated to 60°C and kept warm for use after being uniformly stabilized.

[0087] (2) The reaction chamber was filled with immobilized transesterification lipase (purchased from Qingdao Weilan Biotechnology Group Co., Ltd.) to completely soak the oil and fat mixture.

[0088] (3) Raise the temperature of the reactor jacket to 60 °C and maintain it at that temperature. Pump 60 °C food-grade nitrogen into the reaction system through a bubbler and continue bubbling for 30 min.

[0089] (4) Cover the head and continuously pump the oil and fat mixture into the reaction vessel using a piston pump. Control the flow rate of the reaction product to be 45±2 kg / h. Continue the reaction for 84-108 h to obtain the primary product.

[0090] (5) The primary product is subjected to deacidification, decolorization and deodorization treatment to obtain 1,3-dioleyl-2-palmitoylglycerol.

[0091] Example 6

[0092] This example provides a preferred method for preparing an OPO oil mixture based on Example 1. The method uses the same jacketed enzyme bioreactor as Example 1 and specifically includes the following steps:

[0093] (1) Palm stearyl ester (iodine value 12) with a melting point of 60°C and a long-chain fatty acid with an oleic acid content of 70 wt% were mixed in a mass ratio of 1:6 to obtain a fat mixture, which was heated to 60°C and kept warm for use after being uniformly stabilized.

[0094] (2) The reaction chamber was filled with immobilized transesterification lipase (purchased from Qingdao Weilan Biotechnology Group Co., Ltd.) to completely soak the oil and fat mixture.

[0095] (3) Raise the temperature of the reactor jacket to 60 °C and maintain it at that temperature. Pump 60 °C food-grade nitrogen into the reaction system through a bubbler and continue bubbling for 30 min.

[0096] (4) Cover the head and continuously pump the oil and fat mixture into the reaction vessel using a piston pump. Control the flow rate of the reaction product to be 45±2 kg / h. Continue the reaction for 84-108 h to obtain the primary product.

[0097] (5) The primary product is subjected to deacidification, decolorization and deodorization treatment to obtain 1,3-dioleyl-2-palmitoylglycerol.

[0098] Example 7

[0099] This example provides a preferred method for preparing an OPO oil mixture based on Example 1. The method uses the same jacketed enzyme bioreactor as Example 1 and specifically includes the following steps:

[0100] (1) Palm stearyl ester (iodine value 12) with a melting point of 60°C and a long-chain fatty acid with an oleic acid content of 90 wt% were mixed in a mass ratio of 1:3 to obtain a fat mixture, which was heated to 60°C and kept warm for use after being uniformly stabilized.

[0101] (2) The reaction chamber was filled with immobilized transesterification lipase (purchased from Qingdao Weilan Biotechnology Group Co., Ltd.) to completely soak the oil and fat mixture.

[0102] (3) Raise the temperature of the reactor jacket to 60 °C and maintain it at that temperature. Pump 60 °C food-grade nitrogen into the reaction system through a bubbler and continue bubbling for 30 min.

[0103] (4) Cover the head and continuously pump the oil and fat mixture into the reaction vessel using a piston pump. Control the flow rate of the reaction product to be 45±2 kg / h. Continue the reaction for 84-108 h to obtain the primary product.

[0104] (5) The primary product is subjected to deacidification, decolorization and deodorization treatment to obtain 1,3-dioleyl-2-palmitoylglycerol.

[0105] Example 8

[0106] This example provides a preferred method for preparing an OPO oil mixture based on Example 1. The method uses the same jacketed enzyme bioreactor as Example 1 and specifically includes the following steps:

[0107] (1) Palm stearyl ester with a melting point of 52 °C (iodine value 40) and long-chain fatty acids with an oleic acid content of 80 wt% are mixed in a mass ratio of 1:6 to obtain a fat mixture, which is heated to 55 °C and kept warm for use after being uniformly stabilized.

[0108] (2) The reaction chamber was filled with immobilized transesterification lipase (purchased from Qingdao Weilan Biotechnology Group Co., Ltd.) to completely soak the oil and fat mixture.

[0109] (3) Raise the temperature of the reactor jacket to 55 °C and maintain it at that temperature. Pump 55 °C food-grade nitrogen into the reaction system through a bubbler and continue bubbling for 30 min.

[0110] (4) Cover the head and continuously pump the oil and fat mixture into the reaction vessel using a piston pump. Control the flow rate of the reaction product to be 45±2 kg / h. Continue the reaction for 84-108 h to obtain the primary product.

[0111] (5) The primary product is subjected to deacidification, decolorization and deodorization treatment to obtain 1,3-dioleyl-2-palmitoylglycerol.

[0112] Example 9

[0113] This example provides a preferred method for preparing an OPO oil mixture based on Example 1. The method uses the same jacketed enzyme bioreactor as Example 1 and specifically includes the following steps:

[0114] (1) Palm stearyl ester (iodine value 12) with a melting point of 60 °C and a long-chain fatty acid with an oleic acid content of 90 wt% were mixed in a mass ratio of 1:6 to obtain a fat mixture, which was heated to 68 °C and kept warm for use after being uniformly stabilized.

[0115] (2) The reaction chamber was filled with immobilized transesterification lipase (purchased from Qingdao Weilan Biotechnology Group Co., Ltd.) to completely soak the oil and fat mixture.

[0116] (3) Raise the temperature of the reactor jacket to 68 °C and maintain it at that temperature. Pump 68 °C food-grade nitrogen into the reaction system through a bubbler and continue bubbling for 30 min.

[0117] (4) Cover the head and continuously pump the oil and fat mixture into the reaction vessel using a piston pump. Control the flow rate of the reaction product to be 45±2 kg / h. Continue the reaction for 84-108 h to obtain the primary product.

[0118] (5) The primary product is subjected to deacidification, decolorization and deodorization treatment to obtain 1,3-dioleyl-2-palmitoylglycerol.

[0119] Example 10

[0120] This example provides a method for preparing an OPO oil mixture similar to Example 2. The method utilizes a jacketed enzyme bioreactor similar to Example 1, but does not include a heating device and a heating method disposed in the center of the reaction chamber, which are used as control groups 10-1, 10-2, 10-3 and 10-4.

[0121] During the reaction process, the first temperature sensor and the second temperature sensor are used to record the lowest local temperature T1 and the highest local temperature T2 of the four reaction systems in real time. The recording frequency is 1 time / 3 seconds, and the difference between the lowest local temperature and the highest local temperature is calculated each time. , calculate the average temperature difference of the entire catalytic reaction cycle and degree of dispersion.

[0122] Table 1 Temperature differences under different catalytic systems

[0123]

[0124] After the reaction of the above test group and control group was completed, the content of 1,3-dioleoyl-2-palmitoyl triglyceride (%), the content of SN-2 palmitic acid in the total palmitic acid (%) and the content of palmitic acid triglyceride (%) were determined according to the detection method described in Example 1. The results are shown in Table 2:

[0125] Table 2 Performance of OPO structure esters under different catalytic systems

[0126] Group 1,3-Dioleoyl-2-palmitoyl triglyceride content, % SN-2 palmitic acid accounts for % of total palmitic acid content Palmitic acid triglyceride content, % Example 2 61.8 78.8 0.7 Example 3 60.8 74.2 0.8 Example 4 60.3 73.6 0.9 Example 5 54.5 66.2 3.3 Example 6 51.4 64.8 4.8 Example 7 46.7 59.2 5.7 Example 8 36.5 47.2 7.2 Example 9 52.4 63.6 5.6 Control group 10-1 53.3 63.7 3.7 Control group 10-2 47.8 59.1 7.6 Control group 10-3 58.8 74.3 0.9 Control group 10-4 51.7 61.4 5.9

[0127] Conclusion

[0128] The scheme provided in this application is embodied in Examples 2-4, where the set temperature of the catalytic reaction is 60°C, palm stearate with a melting point of 55-65°C and long-chain fatty acids with an oleic acid content of 70-90 wt% are selected and mixed in proportion, and the lowest local temperature T1 and the highest local temperature T2 are finely controlled during the entire reaction cycle and maintained between 59-61°C. The prepared OPO oil and fat mixture simultaneously satisfies: palmitic acid triglyceride content ≤ 1 wt%, 1,3-dioleic acid-2-palmitic acid triglyceride content ≥ 60 wt%, and SN-2 palmitic acid accounts for ≥ 70 wt% of the total palmitic acid content. Among them, Example 2 further reduces the PPP content to below 1% by optimizing the reaction raw materials and ratios, which exceeds the lower limit that can be achieved by the prior art in this field.

[0129] From the data comparison of Example 2 and Example 5, it can be seen that different melting point palm stearate raw materials have a significant effect on the OPO content, the SN-2 palmitic acid content of the total palmitic acid content and the PPP content, and the low melting point (high iodine value) has a large negative impact on the product quality. From the data comparison of Example 2 and Example 6, it can be seen that different oleic acid raw materials have a significant effect on the OPO, SN-2 palmitic acid content of the total palmitic acid and PPP content, and the low oleic acid content has a large negative impact on the product quality. From the data comparison of Examples 2, 5, 6 and Example 7, it can be seen that the corresponding ratios of palm stearate and oleic acid must be met at the same time to achieve the effect, and neither is indispensable. The effect of the 1:3 ratio is worse than that of 1:6. From the data comparison of Example 2 and Example 8, it can be seen that the low melting point palm stearate is combined with a lower temperature, and the product distribution obtained by exchange is significantly different. From the data comparison of Example 2 and Example 9, it can be seen that increasing the optimal reaction temperature of non-lipase leads to reduced enzyme activity, reduced reaction product content and increased energy consumption. It can be seen from the four control group examples 10-1, 10-2, 10-3 and 10-4 that the enzymatic effect is significantly reduced due to the lack of temperature control.

[0130] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A biosynthetic method for a high-content OPO oil mixture, characterized in that: Palm stearyl with a melting point of 60°C and long-chain fatty acids with an oleic acid content of 90 wt% are mixed in a mass ratio of 1:6 to obtain a fat mixture, and the mixture is added to a reaction system containing an immobilized transesterification lipase, and maintained at a first temperature, wherein the immobilized transesterification lipase is from Rhizomucor miehei; The inert gas is introduced into the reaction system in a continuous or intermittent bubbling manner, and the primary product is obtained by continuous reaction for 84-108 hours; the reaction system also includes a heating device for adjusting the lowest local temperature, and the difference between the highest local temperature and the lowest local temperature does not exceed 2°C; the heating device is located at the center of the reaction system and has a continuous heat exchange contact surface extending in a vertical direction; the temperature of the inert gas is the same as the first temperature, which is 60°C; the continuous reaction is to continuously pump the oil mixture into the reaction system and control the flow rate of the reaction product to be 45±2kg / h; The primary product is subjected to deacidification, decolorization and deodorization treatments to obtain 1,3-dioleyl-2-palmitylglycerol.

2. The biosynthesis method of a high-content OPO grease mixture according to claim 1, characterized in that: The reaction system comprises at least one first temperature sensor capable of detecting the lowest local temperature and one second temperature sensor capable of detecting the highest local temperature.

3. The OPO oil mixture prepared by the synthesis method according to claim 1 or 2, characterized in that: The OPO grease mixture also has the following characteristics: Palmitic acid triglyceride content ≤ 1 wt%; 1,3-dioleyl-2-palmitoyl triglyceride content ≥ 60 wt%; and The SN-2 palmitic acid content accounts for ≥70 wt% of the total palmitic acid content.

4. The OPO grease mixture according to claim 3, characterized in that: The OPO grease mixture also has the following characteristics: Palmitic acid triglyceride content ≤ 0.7 wt%; 1,3-dioleyl-2-palmitoyl triglyceride content ≥ 60 wt%; and The SN-2 palmitic acid content accounts for ≥75 wt% of the total palmitic acid content.

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