A method for extracting oil bodies by combining diafiltration and ultrafiltration

Abstract

The application provides a method for extracting oil bodies by combining diafiltration and ultrafiltration, comprising the following steps: 1) soaking and crushing plant seeds containing oil bodies, separating the material residue, removing the waste residue by filtering through filter cloth, and obtaining a first mixture of protein oil bodies; 2) filtering the first mixture of protein oil bodies through a 5-kDa diafiltration membrane to obtain a second mixture of protein oil bodies; and 3) ultrafiltering the second mixture of protein oil bodies through a 5-kDa ultrafiltration membrane to obtain a third mixture of protein oil bodies. The method for extracting oil bodies by combining diafiltration and ultrafiltration has the advantages that: the method uses ultrafiltration and diafiltration technologies, the equipment has a smaller volume, energy consumption is reduced, and the method is suitable for industrial production of oil bodies. Compared with centrifugal separation products, the product obtained by the method has higher protein content, less water content and more fat content.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fat preparation, and particularly relates to a method for extracting oil bodies by using ultrafiltration technology. BACKGROUND

[0002] Oil bodies mainly exist in plant seeds and are organelles for storing oil. They mainly exist in the form of triglycerides (TAG) and provide carbon and nitrogen sources for seed germination and growth. The structure of oil bodies is simple, the core part is TAG, the outer layer is a monolayer of hydrophilic phospholipids, and the surface is an oil body membrane. Compared with refined plant oil, the existence of the oil body membrane improves the stability of the oil; in addition, the oil bodies obtained by water extraction are natural O / W solutions, which are natural oil-in-water emulsions applied in the food industry (see Figure 1 ) The basic principle of traditional plant oil extraction is to separate oil from other substances in plant tissues to obtain high-purity plant oil. This method usually requires a complex purification and refining process and consumes a large amount of energy. Common methods include pressing, extraction, centrifugation, etc. Among them, the pressing method is a relatively traditional plant oil extraction method, that is, after pretreatment such as crushing and steaming of oil crops, the plant tissues are crushed by a press to separate the oil from other impurities. The oil pressed out contains a certain amount of water and impurities, which needs to be filtered and treated subsequently. The extraction method needs to use an organic solvent to separate the oil from other substances in the oil crops and to perform extraction, separation, purification, etc.

[0003] Because oil body has natural oil-in-water structure, it has great potential to replace traditional vegetable oil and be applied in food industry as natural pre-emulsified oil-in-water emulsion. The most commonly used extraction method of oil body is water extraction, which can extract oil body without damaging its hydrophilic membrane. The water extraction methods developed for this purpose include double screw pressing and blender extraction. The oil body protein mixture obtained after crushing by double screw and blender extraction often contains a large amount of fiber in the extraction liquid, so further cheese cloth and centrifugation or direct centrifugation process is needed to remove large particles of dietary fiber and moisture, and the centrifugal speed is 4000-1000g. For mass extraction of oil body, laboratory centrifuge is difficult to be applied to industrial production due to its low centrifugal efficiency, so disc type separator is used in industry to separate oil body, but the separation efficiency of disc centrifuge is relatively low, and the oil body separated by disc centrifuge contains a large amount of moisture, which is difficult to achieve the effect of high-speed centrifuge. Therefore, the extraction of oil body in industry has been a difficult problem, and the main limitation is the centrifugal process. The large centrifuge used in industry is mainly Decanter centrifuge, that is, disc type centrifuge, and we found that it is difficult to separate the protein and oil body in the suspension by laboratory small disc centrifuge, so the extraction of oil body in industry is still mainly laboratory high-speed centrifuge. SUMMARY

[0004] In view of the deficiencies in the prior art, the present application avoids the use of a centrifuge and proposes a method for extracting oil body by combining diafiltration and ultrafiltration.

[0005] A second object of the present application is to propose a product obtained by the method.

[0006] The technical solution for achieving the above-mentioned objects of the present application is as follows:

[0007] A method for extracting oil body by combining diafiltration and ultrafiltration, comprising the steps of:

[0008] 1) Soaking and crushing plant seeds containing oil body, separating the residue, filtering with filter cloth to further remove waste residue, and obtaining a first mixture of protein oil body;

[0009] 2) Diafiltration of the first mixture of protein oil body with a diafiltration membrane to obtain a second mixture of protein oil body;

[0010] 3) Ultrafiltration of the second mixture of protein oil body with an ultrafiltration membrane to obtain a third mixture of protein oil body.

[0011] The diafiltration of step 2) removes small molecular sugars, polyphenols and salt particles in the first mixture, and then uses ultrafiltration for concentration.

[0012] The plant seeds are rapeseed, tomato seed, sunflower seed, peanut, flaxseed, soybean, sesame, walnut, etc.

[0013] Since the plant seeds contain small molecule sugars and polyphenols, the small molecule sugars and polyphenols are removed by percolation, so that the ultrafiltration concentration can achieve a higher protein and oil body concentration.

[0014] The plant seeds are rapeseed, tomato seed, sunflower seed, peanut, flaxseed, soybean, sesame, walnut, etc.

[0015] The inventors have determined, based on experiments, some more preferred soaking times for plant seeds: in step 1), the plant seeds are rapeseed, and the soaking time is 4-6 hours; the plant seeds are soybean, and the soaking time is 10-12 hours; the plant seeds are sunflower seeds, and the soaking time is 3-5 hours.

[0016] In step 1), the soaked plant seeds are crushed by double-screw extrusion or stirring with a blender, and the residue is separated, and then cheese cloth is used to further remove the residue.

[0017] Since the pore size of ordinary filter cloth is relatively large, cheese cloth with a smaller pore size is preferably used. However, only one layer of cheese cloth may cause the fine residue to block the percolation membrane, so that 2-4 layers of cheese cloth are used for better results.

[0018] Further, in step 1), 2-4 layers of cheese cloth are used for filtration, and the pore size of the cheese cloth is 100-180 μm.

[0019] In step 2), the equipment for percolation includes a water storage container, a first mixture container, a percolation membrane assembly, a pump, and a small molecule substance collection container through the percolation membrane, the pump is used to drive the protein oil body first mixture into the percolation membrane assembly, the percolation membrane assembly includes a percolation membrane and a frame for fixing the percolation membrane, and the first mixture container is sealed (to keep the internal pressure of the container unchanged); the water container and the first mixture container are connected through a water balance pipe to control the total volume of the material in the first mixture container.

[0020] And / or

[0021] The equipment for ultrafiltration includes an air inlet valve, a second mixture container, an ultrafiltration membrane assembly, and a small molecule substance (polysaccharide, polyphenol, etc.) collection container through the ultrafiltration membrane, and high-purity nitrogen gas is input into the ultrafiltration membrane assembly through the air inlet valve.

[0022] The specification of the diafiltration membrane is 3-10 kDa in step 2) and step 3). The specification of the ultrafiltration membrane is 3-10 kDa.

[0023] The specification of the diafiltration membrane is 3-10 kDa in step 2) and step 3). The specification of the ultrafiltration membrane is 3-10 kDa.

[0024] More preferably, the specification of the diafiltration membrane is 5 kDa. The specification of the ultrafiltration membrane is 5 kDa.

[0025] The pressure of the ultrafiltration is 0.35-0.45 MPa in step 3). The maximum pressure of the ultrafiltration is 0.49 MPa, and the sufficient filtration effect can be obtained by using 0.4 MPa, and the energy consumption is relatively low. If the pressure is reduced, the ultrafiltration time is increased, and the final effect of the ultrafiltration is not affected.

[0026] The product obtained by the method.

[0027] The method has the advantages that:

[0028] The method for extracting oil bodies by combining diafiltration and ultrafiltration has the advantages that: the ultrafiltration and diafiltration technologies are used, the equipment volume is smaller, and the energy consumption is reduced. The product obtained by the method has the advantages that: compared with the product obtained by centrifugal separation, the protein content is higher, and the water content is less.

[0029] The method can be used for industrial production of oil bodies instead of centrifugal separation.

[0030] The method does not use organic solvents, and is a more green and environmental protection extraction method.

[0031] The method can obtain oil bodies with higher protein content, and has the advantages that: compared with refined plant oil, the oil bodies are more advantageous for production of foods which need pre-emulsification and contain oil. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The figure is a comparison between oil bodies and refined plant oil.

[0033] Figure 2 The figure is a flow chart of the method for extracting oil bodies by combining diafiltration and ultrafiltration.

[0034] Figure 3 The figure is a structure diagram of a diafiltration equipment.

[0035] Figure 3 In the figure, 1 is a water storage container, 2 is a first mixture container, 3 is a diafiltration membrane assembly, 5 is a pump, and 4 is a small molecule substance collection container.

[0036] Figure 4 The figure is a curve of the change of the protein concentration with time when only ultrafiltration is used. DETAILED DESCRIPTION

[0037] The following examples are intended to illustrate the application but not to limit the scope of the application.

[0038] The means employed in the specification are all the means available in the art unless otherwise specified. The raw materials used are all commercially available.

[0039] The oil body component obtained is detected by Soxhlet extraction and Dumas method.

[0040] Comparative Example 1

[0041] 1) Oilseed soaking: soaking time is 10 h, solid-liquid ratio is 1:5 (m / v, unit g / mL), crushing: the soaked oilseed is crushed by a double-screw extruder, the residue is separated, and the waste residue is further removed by filtering with two layers of cheese cloth to obtain a first protein oil body mixture;

[0042] 2) After crushing, the suspension and waste residue 1 are separated, then the suspension is taken for centrifugation (centrifugal force is 4000-10000 g), and then the upper oil body is scraped to obtain.

[0043] The oil body obtained contains a certain amount of protein, the protein content is about 3.5%, the fat is about 45%, and the rest is water, about 52%.

[0044] Comparative Example 2

[0045] 1) Oilseed soaking: soaking time is 8 h, solid-liquid ratio is 1:6 (m / v), crushing: the soaked oilseed is crushed by a blender, the residue is separated, and the waste residue is removed by filtering with two layers of cheese cloth to obtain a first protein oil body mixture;

[0046] 2) After crushing, the suspension and waste residue 1 are separated, then the suspension is taken for centrifugation (centrifugal force is 4000-10000 g), and then the upper oil body is scraped to obtain.

[0047] The oil body obtained contains a certain amount of protein, the protein content is about 4%, the fat is about 50%, and the rest is water, about 46%.

[0048] Example 1

[0049] The present example provides a method for extracting oil body by combining diafiltration and ultrafiltration, comprising the following steps (see Figure 2 ):

[0050] 1) Oilseed soaking: soaking time is 4 h, solid-liquid ratio is 1:5 (m / v), crushing: the soaked oilseed is crushed by a double-screw extruder, the residue is separated, and the waste residue is removed by filtering with two layers of cheese cloth (pore size 150 μm) to obtain a first protein oil body mixture;

[0051] 2) The protein oil body first mixture is filtered by 5kDa diafiltration membrane to obtain a protein oil body second mixture.

[0052] Figure 3 The equipment for diafiltration is shown. The equipment for diafiltration includes a water container 1, a first mixture container 2, a diafiltration membrane assembly 3, a pump 5 for driving the protein oil body first mixture into the diafiltration membrane assembly, and a small molecule substance collection container 4 through the diafiltration membrane. The water container 1 and the first mixture container 2 are connected through a water balance pipe to keep the volume of the material in the first mixture container unchanged during the diafiltration process. The diafiltration membrane assembly 3 includes a diafiltration membrane and a frame for fixing the diafiltration membrane. The first mixture container 2 is sealed to keep the pressure inside the container unchanged.

[0053] 3) The protein oil body second mixture is ultrafiltered by using an ultrafiltration membrane to obtain a protein oil body third mixture. The PES ultrafiltration membrane used has a specification of 5kDa, and the ultrafiltration pressure is 0.4Mpa.

[0054] The equipment for ultrafiltration includes an air inlet valve, a second mixture container, an ultrafiltration membrane assembly, and a collection container for small molecule sugars, polyphenols and other substances through the ultrafiltration membrane. The air inlet valve is for high-purity nitrogen. The ultrafiltration pressure is less than 0.4Mpa, which can reduce the ultrafiltration speed, but has no effect on the concentration of the final product.

[0055] The protein oil body mixture obtained has a protein content of 12%, a moisture content of 45%, and a fat content of about 43%, which is similar to the composition of oil bodies obtained by centrifugation, but has a higher protein content and a lower moisture content. This also shows that this method can replace the centrifuge to obtain oil bodies in the laboratory.

[0056] Plant oil can be aggregated in water to achieve layering; oil bodies have a hydrophilic membrane on the surface and are dispersed in emulsion in water. Observation by optical microscope and laser confocal microscope confirms that the protein oil body third mixture obtained in this embodiment is oil bodies and part of the protein in the seeds.

[0057] Example 2

[0058] 1) Rapeseed soaking: the soaking time is 4h, the solid-liquid ratio is 1:6 (m / v), and the crushing is performed by using a double-screw extruder. The material residue is separated, and waste residue is removed by filtering through two layers of cheese cloth to obtain a protein oil body first mixture;

[0059] 2) The protein oil body first mixture is filtered by 5kDa diafiltration membrane to obtain a protein oil body second mixture.

[0060] 3) The protein oil body second mixture is ultrafiltered using a 5 kDa ultrafiltration membrane to obtain a protein oil body third mixture. The ultrafiltration membrane used has a specification of 5 kDa, and the pressure of the ultrafiltration is 0.4 MPa.

[0061] The protein oil body mixture obtained has a protein content of about 12.5%, a moisture content of 43%, and a fat content of about 43%.

[0062] Example 3

[0063] 1) The rapeseed is soaked for 7 h, and the solid-liquid ratio is 1:6 (m / v). The soaked rapeseed is crushed using a blender, and the residue is separated. The residue is removed by filtering through two layers of cheese cloth to obtain a protein oil body first mixture;

[0064] 2) The protein oil body first mixture is filtered using a 5 kDa ultrafiltration membrane to obtain a protein oil body second mixture.

[0065] 3) The protein oil body second mixture is ultrafiltered using a PES ultrafiltration membrane to obtain a protein oil body third mixture. The ultrafiltration membrane used has a specification of 5 kDa, and the pressure of the ultrafiltration is 0.4 MPa.

[0066] The protein oil body mixture obtained has a protein content of 12%, a moisture content of 43.5%, and a fat content of about 43%.

[0067] Comparative Example 3

[0068] 1) The rapeseed is soaked for 8 h, and the solid-liquid ratio is 1:6 (m / v). The soaked rapeseed is crushed using a double-screw extruder, and the residue is separated. The residue is removed by filtering through cheese cloth to obtain a protein oil body first mixture;

[0069] 2) The protein oil body first mixture is ultrafiltered using only a 5 kDa ultrafiltration membrane to obtain a protein oil body second mixture. The pressure of the ultrafiltration is 0.35 MPa.

[0070] The protein oil body mixture obtained has a protein content of about 9.6%, a fat content of about 28%, and the remaining 60% is moisture. Referring to Figure 4 , the protein concentration changes over time when only ultrafiltration is used. It can be seen that the highest concentration is only about 9.6%, and the corresponding fat concentration is only about 28%.

[0071] Although the present application has been described by way of examples above, those skilled in the art should understand that improvements and modifications made to the present application without departing from the spirit and essence of the present application shall all fall within the scope of protection of the present application.

Claims

1. A method for extracting grease bodies by combining diafiltration and ultrafiltration, characterized in that: Including steps: 1) soaking and crushing plant seeds containing oil bodies, separating the residue, and filtering through 2 to 4 layers of cheese cloth to further remove the waste residue to obtain a first protein oil body mixture; the cheese cloth has a pore size of 100 to 180 μm; 2) diafiltration of the first protein and grease mixture through a diafiltration membrane to obtain a second protein and grease mixture; the diafiltration equipment includes a water storage container, a first mixture container, a diafiltration membrane assembly, a pump, and a small molecule material collection container after the diafiltration membrane has passed through the diafiltration membrane; the pump is used to drive the first protein and grease mixture into the diafiltration membrane assembly; the diafiltration membrane assembly includes a diafiltration membrane and a frame for fixing the diafiltration membrane; the first mixture container is sealed; the water container and the first mixture container are connected by a water balance pipe to control the total volume of the material in the first mixture container to remain constant; 3) ultrafiltration of the second protein-lipid mixture using an ultrafiltration membrane to obtain a third protein-lipid mixture, wherein the ultrafiltration pressure is 0.35-0.45 MPa; In step 2) and step 3), the specification of the diafiltration membrane is 3kDa~10kDa; the specification of the ultrafiltration membrane is 3kDa~10kDa.

2. The method for extracting grease bodies by combining diafiltration and ultrafiltration according to claim 1, characterized in that: The plant seeds are one of rapeseed, tomato seeds, sunflower seeds, peanuts, flax seeds, soybeans, sesame seeds, and walnuts; the soaking in step 1) is to soak the plant seeds for 3-12 hours, with a material-liquid ratio of 1:4-1:7 m / v kg / L.

3. The method for extracting grease bodies by combining diafiltration and ultrafiltration according to claim 2, characterized in that: In step 1), if the plant seeds are rapeseed, the soaking time is 4 to 6 hours; if the plant seeds are soybeans, the soaking time is 10 to 12 hours; if the plant seeds are sunflower seeds, the soaking time is 3 to 5 hours.

4. The method for extracting grease bodies by combining diafiltration and ultrafiltration according to claim 1, characterized in that: In step 1), the soaked plants are crushed by twin-screw extrusion or stirring with a blender, and the residue is separated, and then cheese cloth is used to further remove the residue.

5. The method for extracting grease bodies by combining diafiltration and ultrafiltration according to claim 1, characterized in that: In step 3), the equipment for ultrafiltration includes an air inlet valve, a second mixture container, an ultrafiltration membrane assembly and a container for small molecules passing through the ultrafiltration membrane. High-purity nitrogen is input into the ultrafiltration membrane assembly through the air inlet valve.

6. The method for extracting grease bodies by combining diafiltration and ultrafiltration according to claim 1, characterized in that: The specification of the diafiltration membrane is 5kDa, and the specification of the ultrafiltration membrane is 5kDa.

7. The product obtained by the method according to any one of claims 1 to 6.

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