A method for producing a fat and oil containing diglyceride, and an apparatus therefor

Abstract

This invention relates to a method and apparatus for preparing oils containing diglycerides. The method employs esterification and includes a process of mixing lipase, fatty acids, and acyl acceptors in a reaction apparatus; and a circulation process in which the material flows out of the reaction apparatus, into a circulation pipeline, and back into the reaction apparatus; maintaining a temperature sufficient for the esterification reaction to occur during the circulation process; wherein the acyl acceptor comprises glycerol and / or monoglycerides. This invention can synthesize high-purity diglycerides, and the purity of the diglycerides remains stable and essentially unchanged with prolonged reaction time.

Description

Technical Field

[0001] This invention belongs to the technical field of edible oil processing technology; more specifically, it relates to a method and equipment for preparing oils containing diglycerides. Background Technology

[0002] Diacylglycerol, also known as fatty acid diglyceride (DAG), is a trace component of natural plant oils and an endogenous intermediate product of fat metabolism in the body. Due to its unique metabolic pathway, it does not cause the accumulation of triglycerides (TAG) and is also beneficial in lowering postprandial blood lipids. Therefore, DAG is becoming increasingly popular.

[0003] From the perspective of preparation mechanism, the main methods for preparing diglycerides include glycerol and fatty acid esterification, partial hydrolysis of natural oils and fats, and glycerol hydrolysis.

[0004] Glycerolysis refers to the process of hydrolyzing natural animal and vegetable oils and glycerol in an anhydrous environment to obtain a mixture of TAG, DAG, and monoglycerides (MAG). TAG is the main form present in natural animal and vegetable oils; therefore, partial hydrolysis of natural oils involves hydrolyzing one fatty acid in the TAG present in natural animal and vegetable oils to obtain DAG. Glycerol and fatty acid esterification involves the esterification reaction of fatty acids and glycerol under the action of a catalyst to obtain diglycerides, while simultaneously producing monoglycerides and triglycerides as byproducts. Glycerol and fatty acid esterification methods include chemical and enzymatic methods. Compared with chemical catalytic esterification, enzymatic catalysis offers milder reaction conditions, lower energy consumption, and produces products with better color and flavor. Therefore, current research mainly focuses on the selection of lipases, optimization of preparation processes, and design of enzyme reactors.

[0005] Currently, glycerol and fatty acid esterification methods have advantages, producing DAG with higher purity compared to hydrolysis and glycerol hydrolysis. However, unlike glycerol hydrolysis, where DAG purity stabilizes after reaching equilibrium with increasing reaction time (though slightly lower), esterification methods suffer from a decrease in theoretical DAG purity with prolonged reaction time (due to further esterification of DAG with free fatty acids during synthesis to form triglycerides). For example, enzymatic esterification is a batch reaction. In actual production, reaction temperature, time, and vacuum parameters are typically set based on experience for industrial-scale operation, making it impossible to predict the reaction endpoint. However, with repeated enzyme use, fixed reaction parameters result in dynamic changes in the system composition at the end of each batch due to enzyme activity, leading to significant batch-to-batch variations. Over-synthesis can cause excessively high TAG levels, while under-synthesis can result in high MAG levels. This makes it impossible to guarantee optimal reaction endpoints for each batch, causing fluctuations in DAG purity and making quality control difficult.

[0006] The current method for detecting DAG (AOCS Cd 11b-91 Mono-and Diglycerides by Capillary Gas Chromatography) usually takes 2-3 hours. If the reaction is monitored in real time, the synthesis reaction of DAG will continue until the detection result is obtained. This will also lead to a gradual decrease in the content of DAG in the reaction product, which is not conducive to the quality control of DAG in the production process.

[0007] Prior art JP 3892928B2 discloses a method for producing diglycerides and a reactor used in the method, wherein a mixture of fatty acids and glycerol is passed through a flow tube reactor containing immobilized lipase or microbial lipase to produce diglycerides with high yield and high purity.

[0008] However, the above-mentioned method for preparing diglycerides using esterification still does not solve the problem of DAG purity decreasing with prolonged reaction time, which is detrimental to the quality control of DAG during the production process.

[0009] Therefore, it is necessary to develop a method and equipment for synthesizing high-purity DAG via esterification that can maintain stability. Summary of the Invention

[0010] To address the technical problems of low purity DAG synthesized by esterification reactions and decreased purity with prolonged reaction time, the present invention aims to provide a method for preparing oils containing diglycerides. This method can synthesize high-purity DAG; and the purity of DAG remains stable and essentially unchanged with prolonged reaction time.

[0011] Another object of the present invention is to provide an apparatus for preparing oils containing diglycerides.

[0012] The above-mentioned objectives of the present invention are achieved through the following technical solutions.

[0013] This invention provides a method for preparing oils containing diglycerides, which employs esterification and includes a process of mixing lipase, fatty acids and acyl acceptors in a reaction apparatus; and a circulation process in which the material in the reaction apparatus flows out of the reaction apparatus into a circulation pipeline and then back into the reactor; the circulation process maintains a temperature sufficient to cause the esterification reaction; wherein the acyl acceptor includes glycerol and / or monoglycerides.

[0014] In one or more embodiments, the flow rate of the material is 0.5-1.8 mt / h; preferably, the flow rate of the material is 0.8-1.4 mt / h.

[0015] In one or more embodiments, the fatty acid is a saturated or unsaturated fatty acid having 2-24 carbon atoms; preferably, the fatty acid is one or more of butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, transoleic acid, linoleic acid, arachidonic acid, cis-9-eicosenoic acid, arachidic acid, behenic acid, erucic acid, eicosapentaenoic acid, and docosahexaenoic acid.

[0016] In one or more embodiments, the lipase is selected from one or more of the following: Candida antarcticis lipase, Thermophilus salviae lipase, Thermophilus salviae lipase variant, Hyphozyma lipase, Rhizopus oryzae lipase, Rhizopus oryzae lipase, Alcaligenes lipase, Pseudomonas pseudoalkalogens lipase, and Pseudomonas cepacia lipase; preferably, the lipase is one or more of the following: CALB, Lipozyme RM IM, Lipozyme TL IM, Novo435, Lipase AP15, Lipase PS, Lipase AK, Lipase A6, Lipase F, Lipase AY30, Lipase G80, Lipase M-10, and Lipase DF IM.

[0017] In one or more embodiments, the esterification reaction is carried out at a temperature of 40-100°C; preferably, the esterification reaction is carried out at a temperature of 45-70°C; preferably, the esterification reaction is carried out at a temperature of 50-60°C.

[0018] In one or more embodiments, the temperature during material circulation is 40-100°C; preferably, the temperature during material circulation is 45-70°C; preferably, the temperature during material circulation is 50-60°C; preferably, during the esterification reaction, the acid value of the reaction system is detected, and the esterification rate of the esterification reaction is calculated based on the acid value, thereby determining the endpoint of the esterification reaction.

[0019] In one or more embodiments, the fatty acid and acyl acceptor participate in the esterification reaction after preheating; preferably, the preheating temperature is not lower than 35°C; preferably, the preheating temperature is 40-100°C; preferably, the preheating temperature is 50-60°C.

[0020] In one or more embodiments, the amount of lipase added is 0.5-10% based on the total weight of fatty acids and acyl receptors; preferably, the amount of lipase added is 3-8% based on the total weight of fatty acids and acyl receptors; preferably, the amount of lipase added is 4-6% based on the total weight of fatty acids and acyl receptors; preferably, the mass ratio of fatty acids to glycerol is 85-90:10-15; preferably, the mass ratio of fatty acids to monoglycerides is 65-70:30-35.

[0021] In one or more embodiments, the purity of DAG is monitored during the reaction, and the reaction is terminated once the purity stabilizes or meets a preset target. Preferably, to reduce the number of samplings, sampling can begin when the esterification rate reaches 60-70%.

[0022] This invention provides an apparatus for preparing oils containing diglycerides, comprising:

[0023] The reaction apparatus includes a circulation outlet and a circulation inlet;

[0024] A circulation pipeline, one end of which is connected to a circulation outlet and the other end of which is connected to a circulation inlet;

[0025] Power system; used to drive the flow of materials between circulation pipelines and reaction equipment;

[0026] A vacuum system is used to remove water from the reaction system.

[0027] In one or more embodiments, the device further includes a temperature control device disposed on a circulation pipeline for maintaining a temperature sufficient for the esterification reaction to occur; preferably, the temperature control device is a heat exchanger; preferably, the reaction apparatus is provided with a stirring device; preferably, the device further includes a filtration device to filter lipases in the reaction products; preferably, the device further includes an online acid value detection device for detecting the acid value of the esterification reaction system; preferably, the device further includes a central control system that works in conjunction with the online acid value detection device to calculate the esterification rate of the esterification reaction based on the acid value.

[0028] In one or more embodiments, the online acid value detection device and the central control system are rapid acid value detection based on the copper soap complexation colorimetric method. During the reaction, the acid value of the reaction system in the esterification tank is detected at regular intervals and converted into the esterification rate by the central control system; the esterification rate = (FA value of fatty acid - FFA value of reaction system) / FFA value of fatty acid * 100 (%), where FFA value = acid value / 2 (%).

[0029] The esterification reaction endpoint is determined by the esterification rate. When the esterification rate reaches 60% or more, preferably 65% ​​or more, even more preferably 70% or more, more preferably 75% or more, and most preferably 80% or more, it is preliminarily determined that the reaction endpoint has been reached. Within this esterification rate range, the purity of DAG is tested multiple times. The reaction is terminated when the purity is found to be stable or meets the requirements.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) This invention provides a method for preparing oils containing diglycerides. By mixing lipase, fatty acid and acyl acceptor and circulating them between the reaction device and the circulation pipeline, high-purity DAG can be synthesized, and the purity can be maintained at more than 70%. Moreover, as the reaction time is extended, the purity of DAG can always remain stable and basically unchanged, which is beneficial to the quality control of DAG.

[0032] (2) This invention provides an apparatus for preparing oils containing diglycerides. By setting up a circulation pipeline connected to the reaction device, the reacted material can flow out of the reaction device, enter the circulation pipeline, and then re-enter the reactor. The apparatus has a simple structure. Through the setup of the reaction device and the circulation pipeline, high-purity DAG can be prepared and the purity of DAG in the material can be kept stable as the reaction time progresses. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the apparatus for preparing oils containing diglycerides according to the present invention.

[0034] Figure 2 This is a schematic diagram of the equipment in Comparative Example 1.

[0035] Figure 3 This is a schematic diagram of the equipment in Comparative Example 2. Detailed Implementation

[0036] In the following description, certain specific details are set forth to provide a thorough understanding of the various embodiments of the invention. However, those skilled in the art will understand that the invention can be practiced without these details. The various embodiments described below are made with the understanding that this disclosure is intended to be illustrative of the claimed subject matter and not to limit the appended claims to the specific embodiments described. Headings used throughout this disclosure are merely for convenience and are not to be construed as limiting the claims in any way. Embodiments described under any heading may be combined with embodiments described under any other heading.

[0037] [Dacrylic acid ester purity]

[0038] The method provided by this invention not only synthesizes high-purity DAG, but also maintains stable DAG purity with prolonged reaction time. In this invention, diglyceride purity is defined as: diglyceride content / (diglyceride content + triglyceride content). As conventionally understood in the art, diglyceride products are primarily mixtures of diglycerides and triglycerides (TAG), and substances such as free fatty acids (FAA) in the reaction products must be removed. Therefore, in this invention, diglyceride purity represents the approximate content of diglycerides in the final product after separation and processing. Improving diglyceride purity is of great significance for diglyceride production.

[0039] [Reaction materials]

[0040] As a reaction raw material of the present invention, the fatty acids suitable for use in the present invention include saturated or unsaturated fatty acids having 2-24 carbon atoms, which may be straight-chain or branched fatty acids; as a non-limiting example of fatty acids, the fatty acids may be one or more of butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, transoleic acid, linoleic acid, arachidonic acid, cis-9-eicosenoic acid, arachidic acid, behenic acid, erucic acid, eicosapentaenoic acid, and docosahexaenoic acid.

[0041] In addition to directly using commercially available fatty acid products, those skilled in the art can also use fatty acids naturally present in or extracted from vegetable oils, vegetable fats, and / or animal oils and fats as alternatives to the fatty acids of this invention. Vegetable oils, vegetable fats, and / or animal oils and fats can be refined oils or crude oils. Refined oils can be oils that have undergone degumming, dewaxing, or decolorization, or any combination thereof. Fatty acids obtained by hydrolyzing vegetable oils, vegetable fats, and / or animal oils and fats can be used; fatty acids obtained by treating these fatty acids through hardening, distillation, or fractionation can be used; and fatty acid derivatives can be used, such as fatty acid derivatives prepared by reacting these fatty acids with phospholipids or by adding ethylene oxide.

[0042] As a non-limiting example of vegetable oils and fats, they may be one of rapeseed oil, soybean oil, cottonseed oil, olive oil, corn oil, coconut oil, palm oil, palm kernel oil, palm oil extract, perilla oil, flaxseed oil, safflower oil, rice bran oil, corn oil, sunflower seed oil, sesame oil, peanut oil, bee oil, wheat germ oil, galangal oil, walnut oil, kiwi seed oil, salvia miltiorrhiza seed oil, grape seed oil, macadamia nut oil, hazelnut oil, pumpkin seed oil, camellia oil, tea seed oil, and borage oil, or any combination thereof. As a non-limiting example of animal oils and fats, they may be one of fish oil, lard, beef tallow, mutton tallow, chicken fat, and butter, or any combination thereof. Preferably, the content of free fatty acids in vegetable oils, vegetable fats, or animal oils, animal fats is higher than 0.25%, higher than 0.30%, higher than 0.35%, higher than 0.50%, higher than 0.75%, higher than 1.0%, higher than 5.0%, higher than 10.0%, higher than 15.0%, higher than 20.0%, higher than 25.0%, higher than 30.0%, higher than 40%, or even higher than 50.0%.

[0043] Methods for hydrolyzing fats and oils include high-temperature, high-pressure (HTHP) decomposition and enzymatic decomposition. HTHP involves adding water to the fats and oils and reacting them under high temperature and pressure to obtain fatty acids and glycerol. Enzymatic decomposition involves adding water to the fats and oils and using fat-hydrolyzing enzymes as catalysts to react them under low temperature conditions to obtain fatty acids and glycerol. The HTHP decomposition and enzymatic decomposition methods can refer to commonly used process conditions and reaction steps in the art, and this invention is not limited thereto.

[0044] This invention can use monoglycerides as acyl acceptors. Using monoglycerides as acyl acceptors, they can also undergo esterification reactions with fatty acids to generate diglycerides. Furthermore, when monoglycerides are added, the solubility of glycerol in the fatty acid phase increases from the initial stage of the reaction, which can improve the reaction rate. However, compared to using glycerol as a reactant in this invention, using monoglycerides is more expensive.

[0045] As reactants of this invention, the aforementioned fatty acids, along with glycerol and / or monoglycerides, can be used in any combination. The mass ratio of fatty acids to glycerol can be referenced to those conventionally used in the art. Depending on the purity of the fatty acids and / or monoglycerides used, those skilled in the art can adjust the mass ratio of lipase, glycerol, and / or monoglycerides as needed. As a non-limiting example of the mass ratio of fatty acids to glycerol, the mass ratio is 85-90:10-15; as a non-limiting example of the mass ratio of fatty acids to monoglycerides, the mass ratio is 65-70:30-35.

[0046] [Lipase]

[0047] As a catalyst for the reaction of this invention, a lipase conventionally used in the art can be employed. More specifically, the lipase used in this invention can be a 1,3-position selective (specific) lipase, which is a lipase that specifically acts on the 1 and 3 positions of glycerol; or a non-selective (non-specific) lipase can be used. The lipase can be derived from animal, plant, and / or microbial sources. As a non-limiting example of a lipase, it may be one or more of the following: Candida antarctica lipase (e.g., Candida antarctica lipase A (CALA), Candida antarctica lipase B (CALB), etc.), Thermomyces lanuginosus lipase, variants of Thermomyces lanuginosus lipase, Hyphozyma lipase, Rhizomucor miehei lipase, Rhizopus oryzae lipase, P. alcaligenes lipase, P. pseudoalcaligenes lipase, and P. cepacia lipase.

[0048] As a non-limiting example of a specific application of lipase, the lipase may be one or more of CALB, Lipozyme RMIM, Lipozyme TL IM, Novo435, Lipase AP15, Lipase PS, Lipase AK, Lipase A6, Lipase F, Lipase AY30, Lipase G80, Lipase M-10, and Lipase DF.

[0049] The amount of lipase added (by weight), based on the total weight of fatty acids and acyl acceptors, can be the conventional amount of lipase added in the art; more specifically, the amount of lipase added is 0.5-10%; preferably, the amount of lipase added is 3-8%; more preferably, the amount of lipase added is 4-5%. In this invention, the amount of lipase added can be 1%, 3%, 5%, 7%, 9%, etc., or any range formed by the above values, such as 1-7%, 3-9%, etc., and this invention is not limited thereto.

[0050] [Reaction and Reaction Conditions]

[0051] This invention provides a method for preparing oils containing diglycerides, which employs esterification and includes a process of mixing lipase, fatty acids and acyl acceptors in a reaction apparatus; and a circulation process in which the material in the reaction apparatus flows out of the reaction apparatus, enters a circulation pipeline, and re-enters the reaction apparatus; during the circulation process, a temperature sufficient to cause the esterification reaction is maintained; wherein the acyl acceptor includes glycerol and / or monoglycerides.

[0052] Esterification reactions are sustained by removing water or water vapor generated during the reaction. Non-limiting examples of removing water or water vapor from the reaction system include: removing water or water vapor by creating a vacuum under reduced pressure; removing water or water vapor by introducing a dry, inert gas (such as nitrogen, helium, or argon); removing water or water vapor by using a desiccant such as a molecular sieve; or a combination of the above methods.

[0053] Optionally, considering the short detection time of acid value and the ability to provide immediate feedback, the esterification rate can be calculated in real time. The curves showing the esterification rate versus time and the DAG purity versus time can be detected to obtain the esterification rate range for the desired DAG purity. The esterification rate can be used to preliminarily determine the reaction endpoint. For example, when the esterification rate reaches 60% or higher, preferably 65% ​​or higher, even more preferably 70% or higher, more preferably 75% or higher, and most preferably 80% or higher, it is preliminarily determined that the reaction endpoint has been reached. After reaching this esterification rate, multiple samples are taken to test the DAG purity. The reaction is terminated once the purity is detected to be stable or meets the requirements.

[0054] In the above method, preferably, water or water vapor is removed by depressurization, which can be operated at low temperature and does not require the recovery of inert gas and dehydrating agent. As a non-limiting example of depressurization, the vacuum level can be controlled within 1-4 mbar. In this invention, the vacuum level can be 1 mbar, 2 mbar, 3 mbar, 4 mbar, etc., or any range formed by the above values, such as 1-3 mbar, 2-4 mbar, etc., and the invention is not limited thereto.

[0055] In the above method, the esterification reaction temperature and time for generating diglycerides using existing esterification methods can be selected as needed. From a reactivity point of view, the reaction temperature of the esterification reaction in this invention can be 40-100℃; preferably, the reaction temperature is 45-70℃; more preferably, the reaction temperature is 50-60℃. Further, when the material is circulated, its temperature during circulation in the circulation pipeline can be 40-100℃; preferably, the temperature is 45-70℃; more preferably, the temperature is 50-60℃. To ensure temperature stability during the reaction and circulation, a heat source of not less than 50℃, not less than 60℃, not less than 70℃, not less than 80℃, not less than 90℃, not less than 100℃, or not less than 110℃ can be used to continuously heat the reaction apparatus or circulation pipeline, thereby maintaining a stable temperature during the esterification reaction and circulation.

[0056] As a non-limiting example of reaction time, the reaction time is not less than 0.1 h; preferably, the reaction time is 0.5-12 h; preferably, the reaction time is 2-10 h; preferably, the reaction time is 6-8 h. If the reaction time is short, although the purity of diglycerides can still be maintained above 70%, the reactants in the system do not react fully, resulting in a low conversion rate and a low yield of diglycerides. As the reaction time increases, the conversion rate of reactants gradually increases in the prior art, but the content of the byproduct TAG also gradually increases, thus reducing the purity of diglycerides. However, in this invention, the purity of diglycerides is consistently maintained above 70% as the reaction time increases.

[0057] In addition, to save reaction time and improve reaction efficiency, the fatty acids and / or acyl acceptors can be preheated at a temperature not lower than 35°C; preferably, the preheating temperature is 40-100°C; more preferably, the preheating temperature is 50-60°C.

[0058] In the reaction process of this invention, the material circulates between the reaction apparatus and the constant-temperature pipeline. The material contains not only the reactant components lipase, fatty acids, and acyl acceptors, but also the generated products such as DAG, TAG, and MAG. As a non-limiting example, the flow rate of the circulating material can be 0.5-1.8 ms / h; preferably, the flow rate is 0.8-1.4 ms / h. In this invention, the flow rate can be 0.7 ms / h, 0.9 ms / h, 1.1 ms / h, 1.3 ms / h, 1.5 ms / h, 1.7 ms / h, or any range formed by the above values, such as 0.5-0.9 ms / h, 0.7-1.5 ms / h, etc., and this invention is not limited thereto.

[0059] The material circulation can begin within 10 minutes after mixing the lipase, fatty acid, and acyl acceptor; preferably, within 8-10 minutes after mixing. As a non-limiting example, the material circulation can begin immediately after mixing the lipase, fatty acid, and acyl acceptor, or within 0.5 minutes, 1.5 minutes, 2.5 minutes, 3.5 minutes, 4.5 minutes, 5.5 minutes, 6.5 minutes, or 7.5 minutes. If the material circulation begins too late, the mixed lipase, fatty acid, and acyl acceptor will have already reacted in the reaction apparatus, ultimately resulting in low diglyceride purity.

[0060] The method provided by this invention also includes a filtration process, specifically: filtering the reaction product after the reaction using a filtration device to separate the lipase in the reaction product. The selection of the filtration device and its specific conditions can refer to known filtration devices and process conditions in the art, and this invention does not limit them.

[0061] The method provided by this invention further includes a purification process for removing FFA, MAG, and glycerol from the product. Those skilled in the art can use conventional methods in the art, such as molecular distillation, to purify the final product and remove these substances.

[0062] In the oil containing diglycerides prepared by the present invention, the content of diacylglycerol + triacylglycerol is preferably 40% by mass or more, more preferably 45-99% by mass, and even more preferably 47-80% by mass.

[0063] This invention stabilizes the purity of diglycerides, meaning that during the preparation of the oil, as the reaction time progresses (e.g., from 2 hours to 8 hours), the purity of the diglycerides remains above a specific range, and / or fluctuates within a specific range. Preferably, the purity of the diglycerides prepared by this invention is above 70%. Preferably, the fluctuation in the purity of the diglycerides in this invention is no higher than 15%; preferably, the fluctuation is no higher than 10%; preferably, the fluctuation is no higher than 5%; preferably, the fluctuation is no higher than 3.3%. The content of diglycerides can be obtained by testing using conventional methods in the art. Specifically, in this invention, the testing method for the diglyceride content is: AOCSOfficial Method Cd 11d-96.

[0064] [Reaction Equipment]

[0065] The above-described method of the present invention can be implemented using various devices in the art. As a non-limiting example of a device for implementing the above-described method of the present invention, the present invention provides a device for preparing oils containing diglycerides, comprising a reaction apparatus, a circulation pipeline, a power system, and a vacuum system. The reaction apparatus includes a circulation outlet and a circulation inlet. One end of the circulation pipeline is connected to the circulation outlet, and the other end is connected to the circulation inlet. The power system is used to drive the material to flow between the circulation pipeline and the reaction apparatus. The vacuum system is used to remove water from the reaction system.

[0066] As a non-limiting example of the present invention, the reaction apparatus can be a reactor conventionally used in the art for preparing oils and fats, such as a reaction vessel or reaction tank. Those skilled in the art can make conventional selections.

[0067] As a non-limiting example of the present invention, the vacuum system of the present invention is mainly used to provide negative pressure to the reaction system, thereby removing water or water vapor by means of reduced pressure. As a non-limiting example of the vacuum system, specific devices include, but are not limited to, vacuum pumps, water ring pumps, reciprocating pumps, slide valve pumps, rotary vane pumps, Roots pumps, and diffusion pumps.

[0068] The material in circulation can be heated or its temperature controlled using conventional heating methods in this field in order to maintain the reaction temperature of the material.

[0069] Preferably, the equipment further includes a temperature control device disposed on the circulation pipeline to maintain a temperature sufficient for the esterification reaction to occur. As a non-limiting example, the temperature control device may be an insulating jacket for heating the circulation pipeline during material circulation; the temperature control device may also be a heat exchanger conventionally used in the art to control the temperature of the circulating material.

[0070] As a non-limiting example of the present invention, the power system of the present invention is disposed between the circulation outlet of the reaction device and the temperature control device.

[0071] More preferably, from the perspective of ease of operation and energy saving, a heat exchanger can be used to control the temperature of the circulating material. The heat exchanger is installed on the circulation pipeline. The heat exchanger can be a heat exchanger conventionally used in the art. More specifically, the heat exchanger can be a plate heat exchanger, a shell-and-tube heat exchanger, or a spiral plate heat exchanger, etc.

[0072] Preferably, the reaction apparatus is further provided with a first feed pipe, a second feed pipe, and a third feed pipe for adding lipase, fatty acid, or acyl acceptor; the reaction apparatus is also provided with a stirring device for uniformly mixing the materials. The selection of the stirring device and its specific conditions can refer to the stirring devices and process conditions known in the art, and the present invention is not limited thereto.

[0073] Preferably, the circulation outlet, power system, and filtration device of the reaction apparatus are connected in sequence. The final reaction product and lipase after the reaction are completed enter the next processing step through the power system and filtration device. The power system can be a pump conventionally used for material transport in the art.

[0074] Preferably, the equipment also includes an online acid value detection device for periodically detecting the acid value of the esterification reaction system during the reaction process. The online acid value detection device can be a conventional detection device used in the art. Specifically, the acid value detection method is the copper soap complexation colorimetric method.

[0075] Preferably, the equipment also includes a central control system, which works in conjunction with an online acid value detection device to calculate the esterification rate of the reaction based on the real-time detected acid value. Esterification rate = (FA value of fatty acid - FFA value of reaction system) / FFA value of fatty acid * 100 (%), FFA value = acid value / 2 (%).

[0076] Raw material information and testing methods

[0077] Oleic acid (85% purity, sourced from high-oleic sunflower seed oil), Qinhuangdao Jinhai Special Edible Oil Industry Co., Ltd.

[0078] Glycerin, Wilmar Oils & Fats Technology (Tianjin) Co., Ltd.

[0079] Lipase, Lipase DF "Amano" IM 15, Amano Enzyme Products Co., Ltd.

[0080] Vacuum systems, vacuum pumps, Alfa Laval (Shanghai) Technology Co., Ltd.

[0081] Temperature control device, plate and frame heat exchanger, Alfa Laval (Shanghai) Technology Co., Ltd.

[0082] Mixing device, Alfa Laval (Shanghai) Technology Co., Ltd.

[0083] Filter machine, Alfa Laval (Shanghai) Technology Co., Ltd.

[0084] The packed bed in Comparative Example 1, Dismebalaster (Shanghai) Trading Co., Ltd.

[0085] The heaters in Comparative Examples 1 and 2, Alfa Laval (Shanghai) Technology Co., Ltd.

[0086] Test methods for DAG and MAG content: AOCS Official Method Cd 11d-96.

[0087] Test method for FFA content: GB 5009.229-2016.

[0088] TAG content: TAG content = 100 - DAG content - MAG content - FFA content.

[0089] DAG theoretical purity a (%) = [DAG content / (DAG content + TAG content)] x 100%.

[0090] Example 1

[0091] This embodiment provides a method for preparing oils containing diglycerides, comprising the following steps:

[0092] (1) As Figure 1 As shown, a mixture of 88 parts oleic acid and 12 parts glycerol, preheated to 55°C, is added to the reaction vessel 6 through the first feed pipe 2 and the second feed pipe 3, respectively. After stirring for 5 minutes, 5 parts lipase are added to the reaction vessel 6 through the third feed pipe 4. After stirring for another 3 minutes, the vacuum pump 1 (vacuum degree of 1 mbar) is started to remove the water and water vapor generated in the reaction.

[0093] (2) Then, valves 11, 10, and 7 are opened, and pump 12 is started so that the lipase and reaction mixture pass through heat exchanger 9 at a flow rate of 0.8 t / h (heat exchanger 9 maintains the temperature of the mixture at 55°C). After exiting heat exchanger 9, the lipase and reaction mixture return to reaction tank 6, and the lipase and reaction mixture circulate between reaction tank 6 and heat exchanger 9. After 8 hours of reaction, the reaction mixture is pumped to filter 14 via pump 13, where the lipase is retained, and the reaction mixture flows out through valve 15.

[0094] Example 2

[0095] This embodiment provides a method for preparing oils containing diglycerides, comprising the following steps:

[0096] (1) As Figure 1 As shown, a mixture of 88 parts oleic acid and 12 parts glycerol, preheated to 55°C, is added to the reaction vessel 6 through the first feed pipe 2 and the second feed pipe 3, respectively. After stirring for 5 minutes by the stirring device 5, 5 parts lipase are added to the reaction vessel 6 through the third feed pipe 4. After stirring for another 3 minutes, the vacuum pump 1 (4 mbar) is started to remove the water and water vapor generated in the reaction.

[0097] (2) Then, valves 11, 10, and 7 are opened, and pump 12 is started so that the lipase and reaction mixture pass through heat exchanger 9 at a flow rate of 1.4 t / h (heat exchanger 9 maintains the temperature of the mixture at 55°C). After exiting heat exchanger 9, the lipase and reaction mixture return to reaction tank 6, and the lipase and reaction mixture circulate between reaction tank 6 and heat exchanger 9. After 8 hours of reaction, the reaction mixture is pumped to filter 14 via pump 13, where the lipase is retained, and the reaction mixture flows out through valve 15.

[0098] Comparative Example 1

[0099] Comparative Example 1 prepared diglycerides using an immobilized enzyme method, the preparation method of which included the following steps:

[0100] A mixture of 88 parts oleic acid and 12 parts glycerol, preheated to 55°C, is added to reaction vessel 6 through the first feed pipe 2 and the second feed pipe 3. The mixture is stirred for 5 minutes, and vacuum pump 1 is activated to remove water and steam generated during the reaction. Then, valves 18 and 19 are opened, and heater 15 is activated to maintain the temperature of the mixture in reaction vessel 6 at 55°C. Next, 5 parts lipase are slowly poured into packed bed 16, and pump 12 is activated to allow the reaction substrate in reaction vessel 6 to flow through packed bed 16 at a flow rate of 0.8 mt / h for reaction. The reaction mixture is then returned to reaction vessel 6. The reaction mixture circulates between reaction vessel 6 and packed bed 16. After 8 hours of reaction, the reaction mixture is pumped through pump 12 to filter 14, where the lipase is retained, and the remaining liquid flows out through valve 22.

[0101] More specifically, in this comparative example, the above preparation method can be based on Figure 2 The device shown is thus implemented. For example... Figure 2 As shown, the equipment used in Comparative Example 1 includes a reaction vessel 6, which includes a first feed pipe 2 and a second feed pipe 3. The top of the reaction vessel 6 is connected to a vacuum pump 1, and a stirring device 5 is installed inside the reaction vessel 6. The circulation outlet of the reaction vessel 6 is connected to the inlet of a packed bed 16 via a pipe, and the outlet of the packed bed 16 is connected to the circulation inlet of the reaction vessel 6 via a pipe. A valve 17, a pump 12, and a valve 20 are sequentially installed on the pipe between the reaction vessel 6 and the packed bed 16. Pump 12, valve 21, filter 14, and valve 22 are sequentially connected via pipes. The two ends of a heater 15 are connected to the reaction vessel 6 via pipes, and valves 18 and 19 are installed on the pipes connecting the heater 15 and the reaction vessel 6. The heater 15 only heats the reaction vessel 6, and the reaction mixture does not flow through the heater 15.

[0102] Comparative Example 2

[0103] In this comparative example, the reaction raw materials and lipase are not circulated, and the preparation method includes the following steps:

[0104] A mixture of 88 parts oleic acid and 12 parts glycerol, preheated to 55°C, is added to reaction vessel 6 through the first feed pipe 2 and the second feed pipe 3, respectively. The stirring device 5 is started, and stirring is performed for 5 minutes. Then, 5 parts lipase are added to reaction vessel 6 through the third feed pipe 4, and stirring continues for 3 minutes. The vacuum pump 1 is then started to remove water and steam generated during the reaction. Simultaneously, valves 24 and 25 are opened, and heater 15 is started to heat reaction vessel 6, maintaining the temperature of the reaction mixture at 55°C. After 8 hours of reaction, the reaction mixture is passed through valve 22 to filter 14, where the lipase is retained, and the remaining liquid flows out through valve 23.

[0105] More specifically, in this comparative example, the above preparation method can be based on Figure 3 The device shown is thus implemented. For example... Figure 3 As shown, the equipment used in Comparative Example 2 includes a reaction vessel 6, which includes a first feed pipe 2, a second feed pipe 3, and a third feed pipe 4. The reaction vessel 6 is connected to a vacuum pump 1. A stirring device 5 is also installed inside the reaction vessel 6. The outlet of the reaction vessel 6 is connected to valve 22, filter 14, and valve 23 in sequence via pipes. Both ends of a heater 15 are connected to the reaction vessel 6 via pipes. Valves 24 and 25 are installed at the pipes connecting the heater 15 and the reaction vessel 6. The heater 15 only heats the reaction vessel 6; the reaction mixture only reacts in the reaction vessel 6 and does not flow through the heater 15.

[0106] Test case

[0107] The composition and content of each component in the reaction mixtures of the above examples and comparative examples were tested at reaction times of 2h, 3h, 4h, 5h, and 8h. The test results of Examples 1, 2, Comparative Examples 1 and 2 are shown in Tables 1, 2, 3, and 4, respectively.

[0108] Table 1. Changes in the components of the reaction mixture in Example 1

[0109] Sampling time (h) DAG (%) MAG (%) FFA (%) TAG (%) <![CDATA[DAG theoretical purity a (%)]]> 2 33.7 18.9 34 13.4 71.5 3 37.4 20.7 28 13.9 72.9 4 39.7 19.9 23.7 16.7 70.4 5 43.1 19.2 21.2 16.5 72.3 8 54 15.7 11 19.3 73.7

[0110] Table 2. Changes in the components of the reaction mixture in Example 2.

[0111]

[0112]

[0113] Table 3. Changes in the components of the reaction mixture in Comparative Example 1.

[0114] Sampling time (h) DAG (%) MAG (%) FFA (%) TAG (%) <![CDATA[DAG theoretical purity a (%)]]> 2 54.5 10.4 20 15.1 78.3 3 54.7 7.8 17.8 19.7 73.5 4 54.2 6.9 14.5 24.4 68.9 5 49.8 7.1 12.9 30.2 62.3 8 46.3 6.4 10.6 36.7 55.8

[0115] Table 4. Changes in the components of the reaction mixture in Comparative Example 2.

[0116] Sampling time (h) DAG (%) MAG (%) FFA (%) TAG (%) <![CDATA[DAG theoretical purity a (%)]]> 2 52.5 12.4 18 17.1 75.4 3 51.7 9.6 15.8 22.9 68.4 4 49.1 6.9 12.5 31.5 60.7 5 43.7 5.07 8.7 42.53 50.7 8 40.1 3.8 6.9 49.2 44.9

[0117] As shown in Tables 1 and 2, more than 50% of the fatty acids were converted within 2 hours, and the purity of DAG was above 70%. As the reaction time increased, the purity of DAG remained stable above 70%.

[0118] As shown in Table 3, when using the immobilized enzyme method to prepare diglycerides, the purity of DAG is above 70% after 2 hours of reaction. However, as the reaction time increases, the byproduct TAG gradually increases, and the purity of DAG decreases to about 55% after 8 hours of reaction.

[0119] As shown in Table 4, when lipase and reactants are mixed and reacted without recycling, the purity of DAG is above 70% after 2 hours of reaction. However, as the reaction time increases, the byproduct TAG gradually increases, and the purity of DAG decreases to about 44% after 8 hours of reaction.

[0120] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for producing an oil and fat containing diglyceride, characterized by, The esterification process includes mixing lipase, fatty acid, and acyl acceptor in a reaction apparatus; and circulating the material from the reaction apparatus out of the apparatus into a circulation pipeline and back into the apparatus; maintaining a temperature sufficient for the esterification reaction to occur during the circulation process; wherein the acyl acceptor includes glycerol and / or monoglyceride.

2. The method of claim 1, wherein, The material flow velocity is 0.5-1.8 mt / h; Preferably, the flow rate of the material is 0.8-1.4 mt / h.

3. The method of claim 1, wherein, The fatty acid is a saturated or unsaturated fatty acid having 2-24 carbon atoms; Preferably, the fatty acid is one or more of butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, transoleic acid, linoleic acid, arachidonic acid, cis-9-eicosenoic acid, arachidic acid, behenic acid, erucic acid, eicosapentaenoic acid, and docosahexaenoic acid.

4. The method of claim 1, wherein, The lipase is selected from one or more of the following: Candida antarcticis lipase, Thermophilus salina lipase, Thermophilus salina lipase variant, Hyphozyma lipase, Rhizopus oryzae lipase, Rhizopus oryzae lipase, Alcaligenes lipase, Pseudomonas alkaligenes lipase, Pseudomonas pseudoalkaligenes lipase, and Pseudomonas cepacia lipase. Preferably, the lipase is one or more of CALB, Lipozyme RM IM, Lipozyme TL IM, Novo435, Lipase AP15, Lipase PS, Lipase AK, Lipase A6, Lipase F, Lipase AY30, Lipase G80, Lipase M-10, and Lipase DF IM.

5. The method of claim 1, wherein, The reaction temperature for the esterification reaction is 40-100℃; Preferably, the reaction temperature of the esterification reaction is 45-70°C; Preferably, the reaction temperature of the esterification reaction is 50-60°C; Preferably, during the esterification reaction, the acid value of the reaction system is detected, and the esterification rate of the esterification reaction is calculated based on the acid value, thereby determining the endpoint of the esterification reaction.

6. The method of claim 1, wherein, The temperature during material circulation is 40-100℃; Preferably, the temperature during material circulation is 45-70℃; Preferably, the temperature during material circulation is 50-60℃.

7. The method of claim 1, wherein, Fatty acids and acyl acceptors participate in esterification reactions after preheating; Preferably, the preheating temperature is not lower than 35°C; Preferably, the preheating temperature is 40-100℃; Preferably, the preheating temperature is 50-60℃.

8. The method of claim 1, wherein, The amount of lipase added is 0.5-10% based on the total weight of fatty acids and acyl acceptors; Preferably, the amount of lipase added is 3-8% based on the total weight of fatty acids and acyl receptors; Preferably, the amount of lipase added is 4-6% based on the total weight of fatty acids and acyl receptors; Preferably, the mass ratio of fatty acids to glycerol is 85-90:10-15; Preferably, the mass ratio of fatty acids to monoglycerides is 65-70:30-35.

9. An apparatus for preparing an oil-and-fat containing diglyceride, characterized by comprising: include: The reaction apparatus includes a circulation outlet and a circulation inlet; A circulation pipeline, one end of which is connected to a circulation outlet and the other end of which is connected to a circulation inlet; The power system is used to drive the flow of materials between the circulation pipeline and the reaction unit; A vacuum system is used to remove water from the reaction system.

10. The device according to claim 9, characterized in that, The equipment also includes a temperature control device, which is installed on the circulation pipeline to maintain a temperature sufficient for the esterification reaction to occur; Preferably, the temperature control device is a heat exchanger; Preferably, the reaction apparatus is equipped with a stirring device; Preferably, the device further includes a filtration device to filter lipase in the reaction products; Preferably, the device further includes an online acid value detection device for detecting the acid value of the esterification reaction system; Preferably, the device further includes a central control system, which works in conjunction with an online acid value detection device to calculate the esterification rate of the esterification reaction based on the acid value.

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