A method for preparing high-quality transparent soybean lecithin

Abstract

The present invention belongs to the field of soybean by-product processing and discloses a method for preparing high-quality transparent soybean lecithin, comprising the following steps: (1) a dual solvent system 1: dissolving soybean lecithin in a non-polar solvent, then adding a certain amount of monohydric alcohol aqueous solution and stirring to obtain a mixed solution 1; (2) centrifuging the mixed solution 1 to remove impurities and collecting the upper non-polar solvent clear liquid; (3) a dual solvent system 2: adding a certain amount of polyol to the collected upper non-polar solvent clear liquid and stirring to obtain a mixed solution 2; (4) centrifuging the mixed solution 2 to remove impurities and water, collecting the upper non-polar solvent clear liquid, and recovering the non-polar solvent to obtain transparent soybean lecithin. The method disclosed in the present invention has the advantages of simple process, low equipment requirements, and solvent recyclability. The prepared soybean lecithin has extremely high transparency and good fluidity, and no substances such as proteins and polysaccharides that affect the transparency of the soybean lecithin are detected.

Description

Technical Field

[0001] The invention belongs to the field of soybean by-product processing, in particular to lecithin deep processing technology, and specifically relates to a method for preparing high-quality transparent soybean lecithin. Background Art

[0002] Lecithin is a byproduct of the oil refining process. Specifically, it is obtained by further processing the byproduct of hydration degumming during the refining of crude soybean oil. Since vegetable oils are essential in our daily lives, lecithin, as a byproduct of oil refining, is abundant.

[0003] Phospholipids are an important component of almost all living cells and are also the main component of nervous tissue, especially the brain and spinal cord. They play a decisive role in the normal metabolism and life processes of cells. In the human body, phospholipids can regulate the normal metabolism of the human body.

[0004] Scientific research shows that soybean lecithin has physiological effects such as delaying aging, enhancing memory, promoting fat metabolism, regulating blood lipids, preventing coronary heart disease and gallstones, anti-tumor, and anti-inflammation; soybean lecithin can be used as an emulsifier in a variety of foods; soybean lecithin has colloidal properties and is a natural amphoteric substance. At the same time, lecithin can regulate the permeability of cell membranes and can be widely used in the cosmetics industry.

[0005] At present, the main characteristic of domestically produced soybean lecithin is poor transparency, and solving the technical problem of poor transparency of soybean lecithin has become a research focus. Patent CN 108003187 A discloses a method for obtaining highly transparent soybean lecithin by diluting the raw material with a non-polar solvent, followed by centrifugal pre-cleaning, cake filtration, re-centrifugal separation, and solvent removal. Patent CN 108969768 A discloses a method for obtaining pharmaceutical transparent soybean lecithin through solvent extraction, low-temperature precipitation, multi-stage membrane filtration, and low-temperature vacuum desolventizing. This method improves the yield and lecithin content of the transparent soybean lecithin, and the multi-stage membrane filtration achieves a high microbial removal rate, resulting in a transparent soybean lecithin that meets the standards for pharmaceutical excipients (for oral use) and has excellent quality. Patent CN 105010721 A discloses a multi-step coupled method for preparing highly transparent concentrated lecithin. The method uses feed-grade concentrated lecithin as the raw material, dissolves the raw material in n-hexane or other non-polar solvents, and undergoes a multi-step coupled process, including centrifugal pre-cleaning, precision filtration, decolorization with food-grade hydrogen peroxide, and adsorption treatment, to obtain a transparent soybean concentrated lecithin with an n-hexane-insoluble content of less than 0.05%, high transparency, and a light color. The article "Preparation of High-Quality Soybean Concentrated Lecithin" discloses a method for preparing high-quality lecithin by mixing feed-grade soybean concentrated lecithin with n-hexane and subjecting it to centrifugal removal, inorganic ceramic membrane filtration, and hydrogen peroxide decolorization.

[0006] The article "Research and Industrial Production of High-Quality Lecithin Prepared by Inorganic Membranes" points out that the impurities that affect the transparency of soybean lecithin are mainly proteins, sugars and other substances, among which the protein content is 45.64% and the sugar content is 33.22% (including 15.86% water-soluble polysaccharides).

[0007] Because lecithin has high viscosity, existing impurity removal technologies all use non-polar solvents to dilute lecithin to reduce viscosity, and then remove impurities in lecithin by technical means such as centrifugation, filter cake, inorganic ceramic membrane or precision filtration. However, the present invention found that although the above technical means can improve the transparency of soybean lecithin, the prepared soybean lecithin still has a hazy appearance and the impurity removal is not thorough. The reason is that some proteins, sugars and some glycoproteins and glycolipids that affect transparency will dissolve in non-polar solvents due to polarity. Although most of the impurities that affect transparency can be removed by centrifugation, filter cake, inorganic ceramic membrane or precision filtration, the impurities dissolved in the non-polar solvent will still affect the transparency of soybean lecithin.

[0008] In addition, existing technologies have disadvantages such as multiple processes, the need for sophisticated equipment, and high equipment investment costs. For example, the method of using inorganic membrane filtration to prepare food-grade concentrated phospholipids, however, the filtration process is prone to membrane clogging, decreased membrane flux, and difficulty in membrane cleaning, and the equipment investment cost is high. Summary of the Invention

[0009] In order to overcome the shortcomings and deficiencies of the prior art, the present invention aims to provide a method for preparing high-quality transparent soybean lecithin, which has simple procedures, low equipment requirements and thorough impurity removal.

[0010] The purpose of the present invention is achieved through the following technical solutions:

[0011] A method for preparing high-quality transparent soybean lecithin comprises the following steps:

[0012] (1) Dual solvent system 1: Soybean lecithin is dissolved in a non-polar solvent, and then a certain amount of monohydric alcohol aqueous solution is added and stirred to obtain a mixed solution 1;

[0013] (2) centrifuging the mixed solution 1 to remove impurities and collecting the upper non-polar solvent clear liquid;

[0014] (3) Dual solvent system 2: a certain amount of polyol is added to the collected upper non-polar solvent clear solution and stirred to obtain mixed solution 2;

[0015] (4) The mixed solution 2 is centrifuged to remove impurities and water, and the upper non-polar solvent layer is collected and the non-polar solvent is recovered to obtain transparent soybean lecithin.

[0016] Preferably, the mass ratio of soybean lecithin to non-polar solvent in step (1) is 1:0.5-1:20;

[0017] Preferably, the volume concentration of the monohydric alcohol aqueous solution in step (1) is 50%-95%.

[0018] Preferably, in step (1), the mass ratio of the non-polar solvent to the monohydric alcohol aqueous solution is 1:0.2-1:1;

[0019] The mass ratio of the non-polar solvent in step (1) to the polyol in step (3) is 1:0.2-1:1.

[0020] Preferably, the non-polar solvent in step (1) is one or more of n-propane, n-butane, n-pentane and n-hexane.

[0021] Preferably, the monohydric alcohol in step (1) is one or more of methanol, ethanol, and propanol; and the polyhydric alcohol in step (3) is one or more of propylene glycol, glycerol, and butanediol.

[0022] Preferably, after the centrifugation in step (2), the product is divided into three layers: upper, middle and lower. The upper layer is a non-polar solvent clear liquid, the middle layer is a monohydric alcohol aqueous solution, and the lower layer is impurities. The middle layer monohydric alcohol aqueous solution is recycled after dehydration.

[0023] Preferably, after centrifugation in step (4), the product is divided into three layers: upper, middle and lower layers. The upper layer is a non-polar solvent clear liquid, the middle layer is a polyol aqueous solution, and the lower layer is impurities. The middle polyol aqueous solution is recycled after dehydration.

[0024] Preferably, the recovered non-polar solvent in step (4) is added to step (1) for reuse.

[0025] Preferably, the centrifugation conditions in steps (2) and (4) are 4000-5000 rpm for 5-10 minutes.

[0026] The soybean lecithin prepared by the preparation method has high transparency. After testing, no protein and sugar were detected in the prepared soybean lecithin (the amount below the equipment detection line can be ignored).

[0027] The present invention uses a dual solvent system 1 formed by a non-polar solvent and a monohydric alcohol aqueous solution and a dual solvent system 2 formed by a non-polar solvent and a polyol solution, and utilizes the difference in polarity between the two different dual solvent systems to effectively remove substances such as proteins, polysaccharides, glycolipids, glycoproteins, etc. that affect the transparency of soybean lecithin.

[0028] The present invention has the following advantages and beneficial effects compared to the prior art:

[0029] 1) The present invention prepares transparent soybean lecithin through a two-step dual solvent system. The soybean lecithin undergoes two steps of dual solvent systems with different polarities, which requires low equipment and can completely remove proteins, sugars, and ash that affect the transparency of the soybean lecithin through a simple process. The prepared soybean lecithin has good transparency and fluidity, and can meet the appearance requirements of medical-grade (injectable) soybean lecithin.

[0030] 2) The two solvents in the two-step dual-solvent system can be separated into layers and recycled in sequence for reuse, while still completely removing proteins, sugars, and ash that affect the transparency of soybean lecithin. The process cost is low. Among them, the polyol in the dual-solvent system 2 can not only remove some polar impurities dissolved in the monohydric alcohol by utilizing its properties, but also act as a water absorbent to remove water absorbed by the lecithin in the first step. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The figure shows the stratification after centrifugation of dual solvent system 1 and dual solvent system 2 (any of Examples 4-7 can be used). The left figure shows a sample solution obtained by centrifugation of dual solvent system 1 (soybean lecithin is dissolved in a non-polar solvent and then a certain amount of monohydric alcohol aqueous solution is added). The top layer of liquid is the non-polar solvent, the middle layer of liquid is the monohydric alcohol aqueous solution, and the bottom layer is impurities. The right side of the figure shows a sample solution obtained by centrifugation of dual solvent system 2 (a certain amount of polyol is added to the collected upper non-polar solvent clear liquid). The top layer of liquid is the non-polar solvent in dual solvent system 1, the middle liquid layer is the polyhydric alcohol aqueous solution, and the bottom layer is impurities. DETAILED DESCRIPTION

[0032] The present invention will be further described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto.

[0033] Example 1

[0034] Take 50g of opaque feed-grade soybean lecithin in a 500mL beaker, then add 200g of n-hexane and stir to completely dissolve the soybean lecithin. Stop stirring and centrifuge the mixture in a 4000r / min centrifuge for 10 minutes, collect the upper clear non-polar solvent layer, and rationally treat the impurities in the bottom layer; recover the solvent of the upper clear non-polar solvent layer to obtain phospholipid sample 1.

[0035] Example 2

[0036] Take 50g of opaque feed-grade soybean lecithin in a 500mL beaker, then add 200g of n-hexane and stir to completely dissolve the soybean lecithin. Stop stirring and add 100g of 80% ethanol aqueous solution. After stirring for 2h, the mixture is centrifuged in a 4000r / min centrifuge for 10 minutes, the upper clear non-polar solvent layer is collected, the middle ethanol aqueous solution layer is recovered and reused, and the impurities in the bottom layer are rationally treated; the solvent of the upper clear non-polar solvent layer is recovered and dehydrated to obtain phospholipid sample 2.

[0037] Example 3

[0038] Take 50g of opaque feed-grade soybean lecithin in a 500mL beaker, then add 200g of n-hexane and stir to completely dissolve the soybean lecithin. Stop stirring and add 100g of propylene glycol. After stirring for 2h, the mixture is centrifuged in a 4000r / min centrifuge for 10 minutes, collect the upper clear non-polar solvent layer, and recover the upper clear non-polar solvent under reduced pressure to obtain phospholipid sample 3.

[0039] Example 4

[0040] Take 50g of opaque feed-grade soybean lecithin in a 500mL beaker, then add 200g of n-hexane and stir to completely dissolve the soybean lecithin. Stop stirring and add 100g of 80% ethanol aqueous solution. After stirring for 2h, centrifuge the mixture at 4000r / min for 10 minutes, collect the upper clear non-polar solvent layer, recycle the middle ethanol aqueous solution layer and reuse it, and rationally treat the impurities at the bottom layer;

[0041] 100 g of propylene glycol was added to the collected upper clear non-polar solvent layer. After stirring for 2 hours, the mixture was centrifuged at 4000 rpm for 10 minutes. The upper clear non-polar solvent layer was collected. The propylene glycol in the middle layer was dehydrated and recovered for reuse. The impurities in the bottom layer were rationally disposed of. The upper clear non-polar solvent layer was recovered to obtain phospholipid sample 4.

[0042] Example 5

[0043] Take 50g of opaque feed-grade soybean lecithin in a 500mL beaker, then add 300g of n-hexane and stir to completely dissolve the soybean lecithin. Stop stirring and add 100g of 90% ethanol aqueous solution. After stirring for 2h, the mixture is centrifuged in a 4000r / min centrifuge for 10 minutes, collect the upper clear non-polar solvent layer, recover and reuse the middle ethanol aqueous solution layer, and rationally treat the impurities at the bottom layer;

[0044] 100 g of glycerol was added to the collected upper clear non-polar solvent layer. After stirring for 4 hours, the mixture was centrifuged at 4000 rpm for 6 minutes. The upper clear non-polar solvent layer was collected. The glycerol in the middle layer was dehydrated and recovered for reuse. The impurities in the bottom layer were rationally disposed of. The upper clear non-polar solvent layer was recovered to obtain phospholipid sample 5.

[0045] Example 6

[0046] Take 50g of opaque feed-grade soybean lecithin in a 500mL beaker, then add 200g of n-hexane and stir to completely dissolve the soybean lecithin. Stop stirring and add 150g of 70% isopropanol aqueous solution. After stirring for 2h, the mixture is centrifuged in a 4000r / min centrifuge for 8 minutes, the upper clear non-polar solvent layer is collected, the middle ethanol aqueous solution layer is recovered and reused, and the impurities at the bottom are rationally treated;

[0047] 200 g of propylene glycol was added to the collected upper clear non-polar solvent layer. After stirring for 2 hours, the mixture was centrifuged at 4000 rpm for 9 minutes. The upper clear non-polar solvent layer was collected. The propylene glycol in the middle layer was dehydrated and recovered for reuse. The impurities in the bottom layer were rationally disposed of. The upper clear non-polar solvent layer was recovered to obtain phospholipid sample 6.

[0048] Example 7

[0049] 800g of opaque feed-grade soybean lecithin was placed in a 5000mL beaker, and then 2500g of n-hexane was added and stirred to completely dissolve the soybean lecithin. Stirring was stopped, and 1200g of an 85% ethanol aqueous solution was added. After stirring for 2h, the mixture was centrifuged in a 4000r / min centrifuge for 8 minutes. The upper clear non-polar solvent layer was collected, the middle ethanol aqueous solution layer was recovered and reused, and the impurities at the bottom layer were rationally treated;

[0050] 1500 g of propylene glycol was added to the collected upper clear non-polar solvent layer. After stirring for 3 hours, the mixture was centrifuged at 4000 rpm for 9 minutes. The upper clear non-polar solvent layer was collected. The propylene glycol in the middle layer was dehydrated and recovered for reuse. The impurities in the bottom layer were rationally disposed of. The upper clear non-polar solvent layer was recovered to obtain phospholipid sample 7.

[0051] Example 8

[0052] 800g of opaque feed-grade soybean lecithin was placed in a 5000mL beaker, and then 2500g of recovered n-hexane was added and stirred to completely dissolve the soybean lecithin. Stirring was stopped, and 1200g of an 85% aqueous ethanol solution (the aqueous ethanol solution was prepared with recovered ethanol) was added. After stirring for 2h, the mixture was centrifuged in a 4000r / min centrifuge for 9 minutes, and the upper clear non-polar solvent layer was collected. The middle aqueous ethanol layer was recovered and reused, and the impurities at the bottom were rationally treated;

[0053] 1800 g of recovered, dehydrated propylene glycol was added to the collected upper, clear non-polar solvent layer. After stirring for 3 hours, the mixture was centrifuged at 4000 rpm for 10 minutes. The upper, clear non-polar solvent layer was collected. The propylene glycol in the middle layer was dehydrated and recovered for reuse. The impurities in the bottom layer were rationally disposed of. The upper, clear non-polar solvent layer was recovered to obtain phospholipid sample 8.

[0054] Table 1

[0055]

[0056] Note: In the present invention, phospholipid content (%) = acetone insoluble matter content (%) - n-hexane insoluble matter content (%);

[0057] “—”: not detected;

[0058] Protein content, refer to GB / T 14489.2-2008; acetone insoluble matter, refer to A3 in GB 1886.238-2016; n-hexane insoluble matter, refer to GB 1886.358-2022; total sugar content is determined by the sulfuric acid-phenol method; color refers to the "Test Method for Export Soybean Lecithin".

[0059] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing high-quality transparent soybean lecithin, characterized in that: The following steps are involved: (1) Dual solvent system 1: Soybean lecithin is dissolved in a non-polar solvent, and then a certain amount of monohydric alcohol aqueous solution is added and stirred to obtain a mixed solution 1; (2) Centrifuge the mixed solution 1 and collect the upper non-polar solvent clear solution; (3) Dual solvent system 2: Add a certain amount of polyol to the collected upper non-polar solvent clear solution and stir to obtain mixed solution 2; (4) Centrifuging the mixed solution 2, collecting the upper non-polar solvent layer, recovering the non-polar solvent, and obtaining transparent soybean lecithin; In step (1), the mass ratio of the non-polar solvent to the monohydric alcohol aqueous solution is 1:0.2-1:1; The mass ratio of the non-polar solvent in step (1) to the polyol in step (3) is 1:0.2-1:1; The mass ratio of soybean lecithin to non-polar solvent in step (1) is 1:0.5-1:20; The volume concentration of the monohydric alcohol aqueous solution in step (1) is 50%-95%; The non-polar solvent in step (1) is n-hexane; The monohydric alcohol in step (1) is one or more of ethanol and propanol, and the polyhydric alcohol in step (3) is one or more of propylene glycol and glycerol.

2. The method for preparing high-quality transparent soybean lecithin according to claim 1, characterized in that: After centrifugation in step (2), the solution is divided into three layers: upper, middle and lower layers. The upper layer is a non-polar solvent clear liquid, the middle layer is a monohydric alcohol aqueous solution, and the lower layer is impurities. The monohydric alcohol aqueous solution in the middle layer is recycled after dehydration.

3. The method for preparing high-quality transparent soybean lecithin according to claim 1, characterized in that: After centrifugation in step (4), the solution is divided into three layers: upper, middle and lower. The upper layer is a non-polar solvent clear liquid, the middle layer is a polyol aqueous solution, and the lower layer is impurities. The polyol aqueous solution in the middle layer is recycled after dehydration.

4. The method for preparing high-quality transparent soybean lecithin according to claim 1, characterized in that: The non-polar solvent recovered in step (4) is added to step (1) for reuse.

5. The method for preparing high-quality transparent soybean lecithin according to claim 1, characterized in that: The centrifugation conditions in steps (2) and (4) are 4000-5000 rpm for 5-10 minutes.

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