Improved aqueous method for extracting seed oil from oilseeds

Abstract

The present invention discloses an improved aqueous method for extracting seed oil from oilseeds, which is carried out according to the following steps: grinding the oilseed kernels into an oilseed kernel slurry; then adding an oil-water separator to the oilseed kernel slurry and stirring well to obtain a mixture of a water-containing hydrophilic substance and a continuous oil phase; the mass ratio of the oil-water separator to the oilseed slurry is 0.05-1:1; finally, separating the mixture by centrifugation or extrusion to obtain a water-containing hydrophilic substance and an oil phase. The improved aqueous method for extracting seed oil from oilseeds provided by the present invention uses a small amount of an oil-water separator to mix with the oilseed slurry to extract the seed oil, overcomes the technical prejudice of those skilled in the art, has a high yield of refined oil, a low water content in the protein part and is easy to dry; the quality of the refined oil is high, and its acid value and peroxide value can reach or even exceed the national first-class oil standard and can be edible without refining; no waste is generated, achieving the goal of fully utilizing the oilseed kernels; the processing cost is low and it is environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of oil processing, and particularly relates to an improved aqueous method for extracting seed oil from oilseeds. Background Art

[0002] There are several common or extensively studied and reported oilseed processing methods as follows. One is the pressing method, mainly referring to the cold pressing method and the hot pressing method, that is, the oilseeds are physically pressed at room temperature or after heating and steaming, and the oil is directly extruded by mechanical force; the second is the pre-pressing - leaching method, that is, after mechanical pre-pressing, then the pressed cake is extracted with an organic solvent, and the residual oil in the meal after leaching is generally about 1%. This technology is the most mature industrial production method of oil at home and abroad at present; the third method is the traditional aqueous method processing technology. All the previously reported aqueous methods use a large proportion of aqueous solution (liquid: solid ratio is usually greater than 2:1). Since the aqueous method has not made a breakthrough for a long time and cannot be industrialized, in recent years, most research reports have tried to apply enzyme hydrolysis to improve the efficiency of the aqueous method processing technology. However, so far, it is still difficult to see the hope that the aqueous enzymatic method can replace the solvent extraction method.

[0003] Defects of the prior art: The hot pressing method can cause protein denaturation and color darkening, resulting in a reduced reuse value of the press cake. The cold pressing method can retain the nutritional components intact, but has a low oil yield. The pre-pressing - leaching method has a large initial equipment investment, uses flammable and explosive solvents, poses risks of fire and explosion, leading to high management costs. The crude oil obtained needs to be refined before consumption, thus increasing equipment investment. At the same time, it causes losses of neutral oil (low yield of refined oil; for example, the leaching rate of crude oil in peanuts by the solvent leaching method can be as high as 98.5 - 99.5%, but 5.2 - 5.4% of neutral oil is lost during the refining process. Therefore, the yield of the finished refined oil is only 93.1 - 94.3%). The aqueous enzymatic method has the following problems: 1. The processing time is long. To improve the oil yield, after adding enzymes, it is necessary to incubate at a certain temperature for a relatively long time to obtain a better oil yield. 2. A large amount of wastewater is generated. For example, analyzed according to the liquid - solid ratio of 2:1, for every 1 ton of oilseeds processed, 2 tons of water need to be added. A large amount of water - soluble substances are dissolved in these 2 tons of water. It is too costly to directly evaporate the water to dryness, and it is almost economically unfeasible. When using the method of recovering macromolecular proteins and then discharging the wastewater, the wastewater still contains other organic substances, and it is very difficult to recover 100% of the proteins. The discharged wastewater will cause serious environmental pollution. 3. Adding a large amount of water will greatly increase the load on the separator, which will increase capital investment and processing costs. 4. After extracting oil and separating the wastewater, the wet protein products and residues such as cellulose obtained after further processing still contain a large amount of water, and their drying is very difficult and costly. 5. A large amount of enzymes need to be used (generally, an enzyme dosage of more than 1% of the raw materials is required to obtain good results), which will greatly increase the cost. 6. Although it has made progress compared with the reported oil extraction method without enzyme water agent, this method still requires a demulsification process, which will further extend the processing time and increase the processing cost. How to effectively solve the above problems has attracted much attention in the field of oilseed processing. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides an improved aqueous agent method for extracting seed oil from oilseeds, aiming to achieve the goals of high oil yield, high drying efficiency, low refining energy consumption, cost reduction, environmental friendliness, and excellent product quality.

[0005] The technical solution adopted by the present invention is as follows: An improved aqueous agent method for extracting seed oil from oilseeds is carried out according to the following steps:

[0006] Step 1: Grind the oilseeds into oilseed slurries;

[0007] Step 2: Add an oil - water separator to the oilseed slurries, stir well to obtain a mixture of water - containing hydrophilic substances and a continuous oil phase; the mass ratio of the oil - water separator to the oilseed slurries is 0.05 - 1:1;

[0008] Step 3: Obtain the water-containing hydrophilic substance and the oil phase by centrifugal separation or extrusion separation of the mixture.

[0009] Preferably, the oil-water separator is an aqueous solution of NaCl or an aqueous solution of Na2CO3.

[0010] Preferably, the oil seeds are peeled to separate the oil seed kernels and the husks, and the oil seed kernels are ground into the oil seed slurry, and the particle size of the oil seed slurry is 80-1000 mesh.

[0011] Preferably, the oil seeds are baked at 70-180°C, cooled and then ground into the oil seed slurry, and the particle size of the oil seed slurry is 80-1000 mesh.

[0012] Preferably, an oil-water separator is added to the oil seed slurry, and the mixture is sufficiently stirred at a temperature of 10-100°C until the hydrophilic substance absorbs water sufficiently and aggregates, and the oily substance aggregates to form a continuous oil phase.

[0013] Preferably, the mass concentration of the aqueous Na2CO3 solution is c1, 0 < c1 ≤ 4.0% wt; the mass concentration of the aqueous NaCl solution is c2, 0 < c2 ≤ 7.0% wt.

[0014] Preferably, the mass ratio of the oil-water separator to the oil seed slurry is 0.05-0.25:1.

[0015] Preferably, the centrifugal separation conditions are a centrifugal speed of 800-10000 revolutions per minute.

[0016] The present invention is further illustrated below with reference to experimental examples:

[0017] The refined oils obtained from different oil seeds by the method of the present invention (aqueous method) and the existing method were compared, and the results are shown in the following table:

[0018]

[0019] Since the refined oil (neutral oil) obtained by the pre-pressing - leaching method contains a large amount of solvent and needs to be further refined to meet the edible standard, the refining loss rate of the neutral oil in this process is about 5.4%. Therefore, the actual (refined oil) yield of the refined oil prepared by the pre-pressing - leaching method is smaller than the data in the table.

[0020] Combined with the above table, it can be seen that the refined oils obtained from different oil seeds by the method of the present invention have a higher yield compared to the refined oils obtained by other oil seed processing methods. When using an aqueous Na2CO3 solution for production, the acid value and peroxide value meet the national first-class oil standard and can be edible without refining.

[0021] Beneficial effects: Compared with the prior art, the improved aqueous method for extracting seed oil from oilseeds provided by the present invention uses a small amount of oil-water separator to mix with the oilseed slurry to extract the seed oil, overcoming the technical prejudice of those skilled in the art. The yield of the refined oil is high, the water content of the protein part is low and it is easy to dry; the quality of the refined oil is high, and its acid value and peroxide value can reach or even exceed the national first-class oil standard and can be consumed without refining; no waste is generated, achieving the goal of fully utilizing the oilseed kernels; the processing cost is low, no wastewater is generated during the process, and it is environmentally friendly. Specific embodiments

[0022] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be described in detail below in conjunction with specific embodiments.

[0023] Example 1

[0024] Step 1: Peel the walnuts to separate the walnut kernels and the husks, and grind the walnut kernels into an oilseed kernel slurry with a particle size of 80 - 1000 mesh; Step 2: Add an aqueous NaCl solution with a mass concentration of 1.5% wt to the walnut kernel slurry, and the weight ratio of the aqueous NaCl solution to the walnut kernel slurry is 1:1. Stir well at a temperature of 10°C until the hydrophilic substances fully absorb water and agglomerate, and the oily substances aggregate to form a continuous oil phase; Step 3: Use a sedimentation centrifuge to separate the mixture into water-containing hydrophilic substances and an oil phase under the condition of 800 - 10000 revolutions per minute.

[0025] The acid value of the walnut oil obtained in this example is 0.23 mg KOH / g, and the peroxide value is 1.56 mmol / kg.

[0026] Example 2

[0027] Step 1: Bake the walnut kernels at 70°C for 50 minutes, cool them and then grind them into a walnut kernel slurry with a particle size of 80 - 1000 mesh; Step 2: Add an aqueous NaCl solution with a mass concentration of 7.0% wt to the walnut kernel slurry, and the mass ratio of the aqueous NaCl solution to the walnut kernel slurry is 0.25:1. Stir well at a temperature of 100°C until the hydrophilic substances fully absorb water and agglomerate in the water phase, and the oily substances aggregate to form a continuous oil phase; Step 3: Use a filtration centrifuge to separate the mixture into water-containing hydrophilic substances and an oil phase under the condition of 800 - 10000 revolutions per minute.

[0028] The acid value of the walnut oil obtained in this example is 0.25 mg KOH / g, and the peroxide value is 1.5 mmol / kg.

[0029] Example 3

[0030] Step 1: Bake peanut kernels at 180°C for 150 minutes, cool and grind them into peanut kernel slurry with a particle size of 80 - 1000 mesh; Step 2: Add an aqueous solution of Na2CO3 with a mass concentration of 0.5% wt to the oilseed kernel slurry, and the mass ratio of the aqueous solution of Na2CO3 to the peanut kernel slurry is 0.05:1. Stir well at 70°C until the hydrophilic substances fully absorb water and aggregate in the aqueous phase, and the oily substances aggregate to form a continuous oil phase; Step 3: Extrude the mixture to obtain a clear oil phase and water-containing hydrophilic substances.

[0031] The acid value of the peanut oil obtained in this example is 0.23 mg KOH / g, and the peroxide value is 2.4 mmol / kg.

[0032] Example 4

[0033] Step 1: Bake sunflower seeds at 110°C for 110 minutes, cool and grind them into oilseed kernel slurry with a particle size of 80 - 1000 mesh; Step 2: Add an aqueous solution of Na2CO3 with a mass concentration of 4.0% wt to the sunflower seed kernel slurry, and the mass ratio of the aqueous solution of Na2CO3 to the sunflower seed kernel slurry is 0.05:1. Stir well at 20°C until the hydrophilic substances fully absorb water and aggregate in the aqueous phase, and the oily substances aggregate to form a continuous oil phase; Step 3: Extrude the mixture to obtain a clear oil phase and water-containing hydrophilic substances.

[0034] The acid value of the sunflower oil obtained in this example is 0.06 mg KOH / g, and the peroxide value is 2.5 mmol / kg.

[0035] Example 5

[0036] Step 1: Put peanut kernels into an oven at 110°C and bake for 90 minutes, cool, remove the skins, and grind them into peanut kernel pulp that passes through a 100-mesh sieve; Step 2: Take 100 kg of peanut kernel pulp, add 15 kg of an aqueous solution containing 1 kg of NaCl, and then stir well at 20°C until the hydrophilic substances fully absorb water and aggregate together and the hydrophobic oil aggregates together to form a continuous oil phase; Step 3: Centrifuge at a speed of 6000 revolutions per minute for 30 minutes using a sedimentation centrifuge to obtain a clear and transparent oil phase and water-containing hydrophilic substances, and the oil yield is greater than 92%.

[0037] Example 6

[0038] Step 1: Put the shelled walnut kernels into an oven at 110°C and bake for 90 minutes, then grind them into walnut paste passing through a 100-mesh sieve; Step 2: Take 100 kg of walnut paste, add 15 kg of an aqueous solution containing 1 kg of NaCl, and then stir well at 20°C until the hydrophilic substances fully absorb water and aggregate together, and the hydrophobic oil aggregates together to form a continuous oil phase; Step 3: Use a filtration centrifuge to centrifuge at a speed of 5000 revolutions per minute for 30 minutes to obtain a clear and transparent oil phase and hydrophilic substances containing water, and the oil yield is greater than 92%.

[0039] Example 7

[0040] Step 1: Put the sunflower kernels into an oven at 110°C and bake for 110 minutes, then grind them into sunflower paste passing through a 300-mesh sieve; Step 2: Take 100 kg of sunflower paste, add 18 kg of an aqueous solution containing 0.5 kg of Na2CO3, and then stir well at 70°C until the hydrophilic substances fully absorb water and aggregate together, and the hydrophobic oil aggregates together to form a continuous oil phase; Step 3: Use a sedimentation centrifuge to centrifuge at a speed of 7000 revolutions per minute for 30 minutes to obtain a clear and transparent oil phase and hydrophilic substances containing water, and the oil yield is greater than 92%.

[0041] Example 8

[0042] Step 1: Put the rapeseeds into an oven at 110°C and bake for 110 minutes. After peeling, grind the kernels into rapeseed paste passing through a 200-mesh sieve; Step 2: Take 100 kg of sunflower paste, add 21 kg of an aqueous solution containing 0.5 kg of Na2CO3, and then stir well at 70°C until the hydrophilic substances fully absorb water and aggregate together, and the hydrophobic oil aggregates together to form a continuous oil phase; Step 3: Use a sedimentation centrifuge to centrifuge at a speed of 5000 revolutions per minute for 30 minutes to obtain a clear and transparent oil phase and hydrophilic substances containing water, and the oil yield is greater than 92%.

[0043] Finally, it should be noted that the above description is only the preferred embodiment of the present invention. Those skilled in the art, under the inspiration of the present invention and without violating the purpose and claims of the present invention, can make various similar representations, and such transformations all fall within the protection scope of the present invention.

Claims

1. An improved aqueous method for extracting seed oil from oilseeds, characterized in that It includes the following steps: Step 1: Grind the oilseeds into oilseed slurry; Step 2: Add an oil-water separation agent to the oilseed slurry and stir well until the hydrophilic substances absorb water and aggregate sufficiently, and the oily substances aggregate to form a continuous oil phase, obtaining a mixture of water-containing hydrophilic substances and a continuous oil phase; The mass ratio of the oil-water separation agent to the oilseed slurry is 0.05 - 0.25:1; The oil-water separation agent is an aqueous NaCl solution or an aqueous Na2CO3 solution; The mass concentration of the aqueous Na2CO3 solution is c1, 0 < c1 ≤ 4.0%wt; The mass concentration of the aqueous NaCl solution is c2, 0 < c2 ≤ 7.0%wt; Step 3: Separate the mixture by centrifugal separation or extrusion separation to obtain water-containing hydrophilic substances and an oil phase; The centrifugal separation is carried out using a filtration centrifuge or a sedimentation centrifuge, and the centrifugal separation conditions are a centrifugal speed of 800 - 10000 revolutions per minute; Specifically, Step 2 is: Add an oil-water separation agent to the oilseed slurry and stir well under the condition of a temperature of 10 - 100°C; Specifically, Step 1 is: Bake the oilseeds at 70 - 180°C for 50 - 150 minutes, cool and then grind them into the oilseed slurry, and the particle size of the oilseed slurry is through an 80 - 1000 mesh sieve.

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