A method for synthesizing diglyceride with a content of 50-95

Abstract

The present invention relates to the technical field of diglyceride synthesis, and specifically discloses a method for synthesizing diglyceride with a content of 50-95, including: S1, mixing dried glycerol and long-chain fatty acids in a molar ratio of 1:3; S2, carrying out esterification under the condition of adding immobilized multifunctional lipase and a co-catalyst, the reaction conditions are pH value 6.8-7.5, temperature 30-40 ° C, and reaction time 6-10 hours; S3, by multi-step separation and purification, including macroporous adsorption resin separation, composite membrane separation and molecular distillation, a diglyceride with a content of 50%-95% is obtained; the present invention significantly improves the esterification reaction rate by introducing the synergistic effect of immobilized multifunctional lipase and calcium ion co-catalyst. Under optimized conditions, the reaction time is only 8 hours, which is significantly shortened from 12-24 hours of the traditional single enzyme catalysis method, reflecting a higher catalytic efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of diglyceride synthesis, and particularly relates to a method for synthesizing diglyceride with a content of 50-95%. Background Art

[0002] In the field of oil chemistry, diacylglycerol (DAG), as a functional oil with unique physiological functions, has received extensive attention in recent years due to its significant effects in lowering blood lipids and preventing cardiovascular diseases. At present, the industrial synthesis of DAG is usually carried out by hydrolysis, which is usually obtained by hydrolyzing triacylglycerol (TAG) under the catalysis of acid or base. However, this method has harsh reaction conditions and is prone to produce a large number of by-products such as free fatty acids (FFA) and monoglycerides (MAG), making the separation and purification of DAG difficult and the purity difficult to reach the ideal level.

[0003] In this regard, the inventors proposed a method for synthesizing diglyceride with a content of 50-95% to solve the above problems. Summary of the invention

[0004] The object of the present invention is to provide a method for synthesizing diglyceride with a content of 50-95%, so as to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for synthesizing diglyceride with a content of 50-95%, comprising the following steps:

[0007] S1. Mix dry glycerol and long-chain fatty acids in a molar ratio of 1:3;

[0008] S2, carrying out esterification reaction under the condition of adding immobilized multifunctional lipase and co-catalyst, the reaction conditions are pH value 6.8-7.5, temperature 30-40° C., and reaction time 6-10 hours;

[0009] S3. Through multi-step separation and purification, including macroporous adsorption resin separation, composite membrane separation and molecular distillation, diglyceride with a content of 50%-95% is obtained.

[0010] Preferably, the immobilization carrier of the immobilized multifunctional lipase is a porous silicon material or modified cellulose.

[0011] Preferably, the co-catalyst is calcium ion or magnesium ion, and the added amount is 0.1%-0.5% of the total mass of the reaction mixture.

[0012] Preferably, the reaction process is assisted by ultrasound with a frequency of 20 kHz and a power of 200 W.

[0013] Preferably, the step of preliminary separation with macroporous adsorption resin is:

[0014] The macroporous adsorption resin was immersed in 95% ethanol for 12 hours, and after removing impurities, it was washed with deionized water until no ethanol remained, and then used for standby;

[0015] The reaction solution was loaded into a macroporous adsorption resin column at a flow rate of 20 mL / min;

[0016] When operated at 25°C, the resin selectively adsorbed DAG, and MAG, TAG, and unreacted fatty acids flowed out of the column, and the effluent was collected for further treatment;

[0017] Use 30%-50% ethanol solution to elute the resin, control the flow rate at 10mL / min, and collect the eluate;

[0018] The ethanol was removed from the eluate by distillation under reduced pressure to obtain a crude DAG liquid.

[0019] Preferably, the composite membrane separation is used to further remove reaction by-products (MAG, TAG) and unreacted fatty acids to improve the purity of DAG, and the steps are:

[0020] The composite membrane system was rinsed with distilled water and cleaned with ethanol solution to enhance water permeability;

[0021] The crude DAG liquid is pumped into the composite membrane separation device at a flow rate of 50-100 mL / min, and the operating pressure is controlled below 0.5 MPa;

[0022] When operated at 40 °C, fatty acids, MAG, and TAG permeate through the membrane pore size, while DAG is retained;

[0023] After stopping the separation, the DAG liquid on the concentrated side was collected and the membrane surface was cleaned with ethanol to maintain the membrane separation performance.

[0024] Preferably, the molecular distillation purification is used to remove residual light and heavy components through efficient molecular distillation to further improve the purity of DAG, and the operating steps are:

[0025] Dehydrating the concentrated side DAG liquid obtained by composite membrane separation to a water content of ≤0.1%;

[0026] Set the distillation conditions to

[0027] Distillation temperature: set between 160°C and 200°C depending on the vacuum degree and the boiling point range of DAG;

[0028] Vacuum degree: <10Pa, lowering the boiling point to protect DAG molecules from high temperature decomposition;

[0029] Scraping speed: 100-200rpm, to ensure even distribution of liquid and prevent overheating or drop;

[0030] The liquid forms a thin film in a scraped film system, separating light impurities, including residual fatty acids and MAG, by rapid evaporation.

[0031] Heavy impurities, including TAG, are deposited at the bottom and discharged;

[0032] The distilled DAG was condensed and collected, and the purity was determined to be 91%-95%;

[0033] Finally, use high-purity ethanol to clean the scraping system to ensure that there is no residue on the equipment.

[0034] Preferably, the long-chain fatty acid is algae lipid, and the carbon chain length is 8-22.

[0035] Preferably, the glycerol is industrial grade glycerol with a moisture content of less than 0.5%.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The present invention significantly improves the esterification reaction rate by introducing the synergistic effect of immobilized multifunctional lipase and calcium ion co-catalyst. Under optimized conditions, the reaction time is only 8 hours, which is significantly shorter than the 12-24 hours of the traditional single enzyme catalysis method, reflecting a higher catalytic efficiency.

[0038] (2) The present invention combines macroporous adsorption resin, composite membrane separation technology and molecular distillation technology, and the purity of diacylglycerol (DAG) is stabilized at 50%-95%, meeting the requirements of various functional oil applications. Compared with traditional methods (such as hydrolysis or glycerol hydrolysis) that produce more by-products, this method has fewer by-products and higher separation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The present invention is a flow chart of a method for synthesizing diglyceride with a content of 50-95%. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Embodiment 1:

[0042] See also Figure 1As shown, a method for synthesizing diglyceride with a content of 50-95% comprises the following steps:

[0043] Raw materials and equipment

[0044] raw material:

[0045] Glycerol (industrial grade, moisture ≤ 0.5%), 5.679g

[0046] Fatty acids (carbon chain length C16-C18, derived from algae extract), 4.321 g

[0047] Enzyme system:

[0048] Immobilized multifunctional lipase, immobilized on porous silicon material, enzyme activity 240U / g

[0049] Co-catalyst:

[0050] Calcium ions (Ca 2+ ), concentration is 0.2% (based on the total mass of reactants)

[0051] equipment:

[0052] Constant temperature reactor with magnetic stirring function

[0053] Ultrasonic generator (frequency 20kHz, power 200W)

[0054] Macroporous adsorption resin column

[0055] Membrane separation device and molecular distillation equipment

[0056] Experimental procedures

[0057] Raw material mixing

[0058] Glycerol and fatty acid were mixed at a molar ratio of 1:3, 0.4 g of phosphate buffer with a pH value of 7.0 was added, and the mixture was stirred evenly.

[0059] Immobilized enzyme and co-catalyst addition

[0060] Immobilized multifunctional lipase (the mass of the enzyme accounts for 5% of the total mass of the reactants) and calcium ion solution (accounting for 0.2% of the total mass of the reactants) are added into the mixed solution.

[0061] Esterification reaction

[0062] The reactor temperature was controlled at 35° C., magnetic stirring (500 rpm) was started, ultrasonic assistance was turned on, and the reaction was continued for 8 hours.

[0063] Reaction end processing

[0064] The reaction solution was filtered to recover the immobilized enzyme and the enzyme was stored for reuse.

[0065] Isolation and purification

[0066] The reaction solution was separated by macroporous adsorption resin to preliminarily extract diglyceride.

[0067] The monoglycerides and triglycerides are further removed using a composite membrane separation unit.

[0068] Through molecular distillation purification, diglyceride with a purity of 91.2% was finally obtained.

[0069] As can be seen from the above, by introducing the synergistic effect of immobilized multifunctional lipase and calcium ion co-catalyst, the present invention significantly improves the esterification reaction rate. Under optimized conditions, the reaction time is only 8 hours, which is significantly shorter than the 12-24 hours of the traditional single enzyme catalysis method, reflecting a higher catalytic efficiency;

[0070] Combining macroporous adsorption resin, composite membrane separation technology and molecular distillation technology, the purity of diacylglycerol (DAG) is stabilized at 50%-95%, meeting the requirements of various functional oil applications. Compared with traditional methods (such as hydrolysis or glycerol hydrolysis) that produce more by-products, this method has fewer by-products and higher separation efficiency.

[0071] Embodiment 2:

[0072] Performance Testing

[0073] 1. Determination of diglyceride content

[0074] Equipment: Gas Chromatograph (GC)

[0075] condition:

[0076] Chromatographic column: HP-5 (30m×0.25mm×0.25μm)

[0077] Injection temperature: 250℃

[0078] Program heating: initial temperature 50℃, heating rate 10℃ / min, final temperature 250℃

[0079] Carrier gas: nitrogen, flow rate 1.0 mL / min

[0080] method:

[0081] Take 2 mL of sample, dilute it and analyze it, record the peak areas of diacylglycerol (DAG), monoacylglycerol (MAG) and triacylglycerol (TAG), and calculate the DAG content.

[0082] 2. Determination of enzyme activity recovery rate

[0083] Equipment: UV spectrophotometer

[0084] method:

[0085] The recovered immobilized enzyme was placed in a substrate simulation solution for reaction, the concentration change of the generated DAG was measured, compared with the initial enzyme activity, and the enzyme activity recovery rate was calculated.

[0086] 3. Product stability test

[0087] condition:

[0088] Storage temperature: 4℃ and 25℃

[0089] Storage time: 1 month

[0090] Test content: DAG purity and acid value

[0091] method:

[0092] Samples were taken regularly to analyze DAG purity (gas chromatography) and acid value (acid-base titration).

[0093] Final data and results

[0094] DAG content:

[0095] Initial reaction product content: 55.6%

[0096] Final content after separation and purification: 91.2%

[0097] Enzyme activity recovery rate:

[0098] After the immobilized enzyme was used for 5 times, the enzyme activity retention rate was 87.5%.

[0099] Product stability:

[0100] After storage at 25°C for one month, the purity of DAG did not decrease significantly (maintained above 90%), and the acid value did not change by more than 0.2 mgKOH / g.

[0101] It can be seen from the above that, under the synergistic effect of the immobilized enzyme and the co-catalyst, the esterification reaction time is shortened and the yield is significantly improved.

[0102] The separation and purification technology is highly efficient, and the final DAG purity can reach over 91%, meeting the needs of industrial applications.

[0103] Immobilized enzymes can be reused, which reduces costs and improves the economy and sustainability of the process.

[0104] Embodiment three:

[0105] Esterification reaction conditions Glycerol to fatty acid molar ratio: 1:4 Enzyme addition: immobilized enzyme activity 240U / g Co-catalyst: calcium ion concentration 0.2%

[0106] Reaction temperature: 35℃ Reaction time: 8 hours

[0107] Separation and purification adsorption resin model: D101

[0108] Membrane separation pore size: 0.2μm

[0109] Molecular distillation temperature: 190℃Results

[0110] Initial purity: 56.7%

[0111] Final purity: 90.5%

[0112] Embodiment 4:

[0113] Esterification reaction conditions Glycerol to fatty acid molar ratio: 1:3 Enzyme addition: immobilized enzyme activity 300U / g Co-catalyst: magnesium ion concentration 0.3%

[0114] Reaction temperature: 40℃ Reaction time: 10 hours

[0115] Separation and purification adsorption resin model: XAD-16

[0116] Membrane separation pore size: 0.3μm

[0117] Molecular distillation temperature: 180℃Results

[0118] Initial purity: 54.8%

[0119] Final purity: 88.6%

[0120] Embodiment five:

[0121] Esterification reaction conditions

[0122] Glycerol to fatty acid molar ratio: 1:5

[0123] Enzyme addition amount: immobilized enzyme activity 220U / g

[0124] Co-catalyst: Calcium ion concentration 0.1%

[0125] Reaction temperature: 30℃

[0126] Reaction time: 6 hours

[0127] Separation and purification

[0128] Adsorption resin model: D301

[0129] Membrane separation pore size: 0.15 μm

[0130] Molecular distillation temperature: 200℃

[0131] result

[0132] Initial purity: 57.4%

[0133] Final purity: 91.8%

[0134] Embodiment six:

[0135] Esterification reaction conditions

[0136] Glycerol to fatty acid molar ratio: 1:3.5

[0137] Enzyme addition amount: immobilized enzyme activity 250U / g

[0138] Co-catalyst: a mixed solution of calcium ions and magnesium ions (ratio 1:1), concentration 0.25% Reaction temperature: 37°C

[0139] Response time: 7 hours

[0140] Separation and purification

[0141] Adsorption resin model: XAD-7

[0142] Membrane separation pore size: 0.25 μm

[0143] Molecular distillation temperature: 195℃

[0144] result

[0145] Initial purity: 55.3%

[0146] Final purity: 89.4%

[0147] Embodiment seven:

[0148] Esterification reaction conditions

[0149] Glycerol to fatty acid molar ratio: 1:4.5

[0150] Enzyme addition amount: immobilized enzyme activity 260U / g

[0151] Co-catalyst: Calcium ion concentration 0.2%

[0152] Reaction temperature: 35℃

[0153] Response time: 9 hours

[0154] Separation and purification

[0155] Adsorption resin model: D201

[0156] Membrane separation pore size: 0.18 μm

[0157] Molecular distillation temperature: 185℃

[0158] result

[0159] Initial purity: 58.9%

[0160] Final purity: 92.3%

[0161] From the above, we can see that by optimizing the reaction conditions and separation technology, the final purity can be stably increased to 87%-95% based on the initial purity of 50%-60% through a series of separation and purification steps. These data show that the method has good adaptability and stability and meets the needs of industrial application.

[0162] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0163] In the drawings of the embodiments disclosed in the present invention, only the structures related to the embodiments disclosed in the present invention are involved, and other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of the present invention can be combined with each other.

[0164] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for synthesizing diglyceride with a content of 50-95%, characterized in that: The following steps are involved: S1. Mix dry glycerol and long-chain fatty acids in a molar ratio of 1:3; S2, carrying out esterification reaction under the condition of adding immobilized multifunctional lipase and co-catalyst, the reaction conditions are pH value 6.8-7.5, temperature 30-40° C., and reaction time 6-10 hours; S3. Through multi-step separation and purification, including macroporous adsorption resin separation, composite membrane separation and molecular distillation, diglyceride with a content of 50%-95% is obtained.

2. A method for synthesizing diglyceride with a content of 50-95% according to claim 1, characterized in that: The immobilized carrier of the immobilized multifunctional lipase is a porous silicon material or modified cellulose.

3. A method for synthesizing diglyceride with a content of 50-95% according to claim 1, characterized in that: The co-catalyst is calcium ion or magnesium ion, and the added amount is 0.1%-0.5% of the total mass of the reaction mixture.

4. A method for synthesizing diglyceride with a content of 50-95% according to claim 1, characterized in that: The reaction process is assisted by ultrasound with a frequency of 20 kHz and a power of 200 W.

5. A method for synthesizing diglyceride with a content of 50-95% according to claim 1, characterized in that: The steps of preliminary separation with macroporous adsorption resin are as follows: The macroporous adsorption resin was immersed in 95% ethanol for 12 hours, and after removing impurities, it was washed with deionized water until no ethanol remained, and then used for standby; The reaction solution was loaded into a macroporous adsorption resin column at a flow rate of 20 mL / min; When operated at 25°C, the resin selectively adsorbed DAG, and MAG, TAG, and unreacted fatty acids flowed out of the column, and the effluent was collected for further treatment; Use 30%-50% ethanol solution to elute the resin, control the flow rate at 10mL / min, and collect the eluate; The ethanol was removed from the eluate by distillation under reduced pressure to obtain a crude DAG liquid.

6. A method for synthesizing diglyceride with a content of 50-95% according to claim 5, characterized in that: The composite membrane separation is used to further remove reaction byproducts (MAG, TAG) and unreacted fatty acids to improve the purity of DAG, and the steps are: The composite membrane system was rinsed with distilled water and cleaned with ethanol solution to enhance water permeability; The crude DAG liquid is pumped into the composite membrane separation device at a flow rate of 50-100 mL / min, and the operating pressure is controlled below 0.5 MPa; When operated at 40 °C, fatty acids, MAG, and TAG permeate through the membrane pore size, while DAG is retained; After the separation was stopped, the DAG liquid on the concentrated side was collected and the membrane surface was cleaned with ethanol.

7. A method for synthesizing diglyceride with a content of 50-95% according to claim 6, characterized in that: The molecular distillation purification is used to remove the residual light and heavy components through efficient molecular distillation to further improve the purity of DAG. The operation steps are: Dehydrating the concentrated side DAG liquid obtained by composite membrane separation to a water content of ≤0.1%; Set the distillation conditions to Distillation temperature: set between 160°C and 200°C depending on the vacuum degree and the boiling point range of DAG; Vacuum degree: <10Pa, lowering the boiling point to protect DAG molecules from high temperature decomposition; Scraping speed: 100-200rpm, to ensure even distribution of liquid and prevent overheating or drop; The liquid forms a thin film in a scraped film system, separating light impurities, including residual fatty acids and MAG, by rapid evaporation. Heavy impurities, including TAG, are deposited at the bottom and discharged; The distilled DAG was condensed and collected, and the purity was determined to be 91%-95%; Finally, use high-purity ethanol to clean the scraping system.

8. A method for synthesizing diglyceride with a content of 50-95% according to claim 1, characterized in that: The long-chain fatty acid is algae oil, and the carbon chain length is 8-22.

9. A method for synthesizing diglyceride with a content of 50-95% according to claim 1, characterized in that: The glycerol is industrial grade glycerol with a moisture content of less than 0.5%.

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