CN102388988B - Separated extraction method of microorganism oil - Google Patents

Abstract

The invention relates to a separated extraction method of microorganism oil, which is characterized by comprising the following steps: firstly, homogenizing, stirring microorganism oil to be in separated extraction uniformly; secondly, breaking crystals; thirdly, cooling and crystallizing, crystallizing the heat-insulation microorganism oil for 4-7h at the temperature being 4 DEG C, and then arranging the heat-insulation microorganism oil for 1-4h at the low temperature being 10 DEG C, thus obtaining thick slurry containing solid crystallization; fourthly, adding surface active agent water solution in the thick slurry containing solid crystallization, and stirring, thus obtaining elusion system; fifthly, conducting centrifugal separation to obtain liquid oil, standing the emulsion system for 1-5h at the low temperature being 5-10 DEG C, centrifuging the emulsion system in a cooling centrifuge, separating liquid components in a light phase mode, putting the liquid components in light phase in water for cleaning, and dehydrating and drying the liquid components in light phase, thus obtaining the liquid oil of the microorganism oil; and sixthly, breaking the emulsion to obtain solid grease. The liquid oil of the microorganism separated and extracted by the method is not easy to solidify at lower temperature, the method procedure is simple and the cost is low.

Description

A kind of fractionation method of microbial oil

technical field

The invention belongs to the field of food science, and in particular relates to a method for fractionating microbial oil.

Background technique

Microbial oil is another new human edible oil resource developed after vegetable oil and animal oil. Microbial oil, also known as single-cell oil, is oil produced by microorganisms such as yeast, mold, bacteria, and algae under certain conditions using carbohydrates, hydrocarbons, and ordinary oils as carbon sources, nitrogen sources, supplemented by inorganic salts, and other oils. Lipids of commercial value. Microbial oil production not only has the advantages of high oil content, short production cycle, not affected by seasons, and does not occupy cultivated land, but also can use methods such as cell fusion and cell mutagenesis to make microorganisms produce high-nutrition oil or oil composed of certain specific fatty acids. For example, functional oils containing long-chain polyunsaturated fatty acids (LC-PUFAs) such as arachidonic acid (ARA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). LC-PUFAs have obvious effects in preventing cardiovascular diseases, lowering blood lipids, lowering cholesterol, losing weight, inhibiting tumor growth, and anti-inflammation. Since the 1990s, the development and utilization of microorganisms for the production of functional oils has become a hot spot, such as the research on the use of microorganisms to produce ARA, EPA, DHA and other functional oils with high nutritional value and special health functions. ARA belongs to the omega-6 series of long-chain polyunsaturated fatty acids (LC-PUFA), which is widely distributed in the human body, and its content in the brain and nerve tissues generally accounts for 40% to 50% of the total amount of polyunsaturated fatty acids. Up to 70%, it is an essential substance for brain function and retinal development; in addition, ARA also has the function of promoting growth and development, and the effect of lowering blood sugar, blood fat and blood cholesterol.

However, when microbial oil is stored at low temperature, it will solidify. For example, when the temperature is low in winter, it will become solid or semi-solid, which not only causes poor fluidity of the oil, is inconvenient to use, and is difficult to store; Poor performance, thereby reducing the nutritional value of microbial oil and the quality of oily food. Oil fractionation is based on the difference in the melting points of different fatty acid triglycerides in the oil, through cooling to crystallize the high melting point components, and obtaining components with different melting points through filtration or centrifugation. Oil fractionation can classify complex natural oils into relatively single products, realize the separation of liquid oils and solid fats with different melting points, improve the adaptability of oils to different use requirements, expand the use of oils, and increase the use value of oils and economic value.

At present, oil fractionation techniques mainly include dry fractionation, solvent fractionation and surfactant fractionation. Dry fractionation refers to the method of slowly cooling the dissolved oil to a certain extent without adding any solvent, and then filtering to separate crystals and precipitate solid esters. Dry fractionation is divided into three steps: heat treatment; cooling to form crystal nuclei and allow the crystals to grow and mature; and filtration to separate the palmitate from the solid. Although dry fractionation has its unique advantages, the efficiency of dry fractionation is low, and the liquid oil content in solid fat is relatively high, which makes the crystal grade of solid fat and liquid oil low. Solvent fractionation refers to a fractionation method in which a certain solvent is added to oil in proportion to form a mixed oil system, and then cooled and crystallized and fractionated. The solvent fractionation method can form stable crystals that are easy to filter, improve the separation effect, increase the separation yield, shorten the separation time, and improve the purity of the separation product. The solvent fractionation method has high fractionation efficiency and good quality of solid lipid components. However, due to the low crystallization temperature and solvent loss involved in the fractionation process, the investment is large and the production cost is high. The hexane, acetone, and isopropanol used as solvents are flammable. The surfactant fractionation method refers to adding a surfactant after the oil is cooled and crystallized to improve the interfacial tension between the oil and the fat, and to form a suspension of the fat in the aqueous surfactant solution by virtue of the affinity between the fat and the surfactant to promote Method of Lipid Crystal Isolation. The process includes cooling crystallization, surfactant wetting, centrifugal separation and surfactant recovery. The fractionation and separation efficiency of the surfactant method is high, the product quality is good, the application is wide, and it is suitable for large-scale production.

Contents of the invention

In order to solve the problem that microbial oil is easy to solidify when the temperature is low (10-20 ° C), the object of the invention is to provide a method for fractionating microbial oil, the liquid oil of the microbial oil proposed by the method is separated when the temperature is low (10-20° C.) is not easy to solidify, and the method has simple procedures and low cost.

In order to achieve the above object, the technical scheme of the present invention is: a kind of fractionation method of microbial oil, it is characterized in that it comprises the steps:

1) Homogenization: Stir the microbial oil (or microbial oil) to be fractionated evenly;

2) Crystal breaking: After heating the uniformly stirred microbial oil to 25-30°C, keep it warm for 5-10 minutes;

Microbial oils destroy the naturally formed uneven crystal nuclei before freezing. During the refining, transportation, and storage of microbial oils, crystals are precipitated because the temperature of microbial oils is lower than the freezing point of solid fats; this part of crystals is due to non-uniform cooling. The precipitated ones have different crystal forms and different grain sizes. When it is transferred to the freezing and crystallization stage, it will not be conducive to the uniform growth and maturation of lipid crystals, causing defects in the crystal itself, affecting oil fractionation, and breaking crystals usually melts oil Raise the temperature above the melting point of the solid fat and keep it for 5-10 minutes;

3) Freeze crystallization (gradual cooling process): crystallize the microbial oil after step 2) at 4°C for 4-7h (full under low temperature conditions), and then place it under low temperature conditions of 10°C for 1-4h to obtain solid crystals The viscous slurry (at this time, the grease material forms a viscous slurry containing solid crystals after being cooled and frozen);

4) Addition of surfactant solution: according to the volume ratio of thick slurry containing solid crystals: aqueous surfactant solution = 1: 0.5-1: 2, select the thick slurry containing solid crystals and aqueous surfactant solution; Wherein, the surfactant aqueous solution is composed of surfactant, inorganic salt and water, the concentration of surfactant is 0.08-0.4wt%, and the concentration of inorganic salt is 0.5-3wt%;

Add an aqueous surfactant solution to the viscous slurry containing solid crystals, and stir for 0.5-1.0 hours to obtain an emulsion system;

Stir fully to disperse the mixed system evenly to form an emulsion system. The liquid components in the oil still remain in the liquid phase and cannot be wetted by the surfactant, so they become fine droplets and disperse in the aqueous solution under the action of stirring, and are dispersed by the surfactant. The molecularly wrapped crystalline particles are fully wetted, eliminating the liquid components attached to the crystalline surface, and then transfer to the water phase;

5) Centrifuge to obtain liquid oil: put the emulsion system in step 4) at a low temperature of 5-10°C for 0.5-5h, centrifuge in a refrigerated centrifuge, the liquid component will be separated as a light phase, add water to wash After dehydration and drying (drying at 20-25°C for 2-6h), the liquid oil (product) of microbial oil can be obtained;

The aqueous surfactant solution with solid crystals suspended is separated as a heavy phase to obtain a solid phase oil mixture.

The surfactant is sodium dodecyl sulfate (SDS), sodium alkylbenzene sulfonate or sodium fatty alcohol sulfate, etc.

Inorganic salts are magnesium sulfate (MgSO ₄ ), sodium sulfate, aluminum sulfate, or sodium chloride.

The centrifugation conditions in step 5) are: 3000-6000rpm, centrifugation for 5-10min.

6) Obtain solid fat after demulsification: After taking out the liquid oil (i.e. the liquid component) of the microbial oil, the obtained solid-phase oil mixture is heated at 80-95°C for 2-10 minutes to demulsify, the crystallization is melted, and the solid component is Separate from the water phase, remove the lower water phase to obtain the solid fat component, add water to wash to remove the residual surfactant aqueous solution, and after dehydration and drying, obtain the solid stearin of microbial oil.

The liquid oil (which is the product that the present invention needs to obtain) after fractionation of the microbial bacterial oil of the present invention, the transparent time can reach more than 120h under the condition of 10 ℃ (its physicochemical index sees Table 1). The invention solves the problem that the microbial oil is easy to solidify when the temperature is low (<20° C.), thereby improving the use value and economic value of the microbial oil.

The comparison (embodiment 1-5) of table 1 physicochemical index

The beneficial effects of the present invention are:

1) The liquid oil of the microbial oil proposed by this method is not easy to solidify when the temperature is low (10-20°C). The liquid oil (which is the product required by the present invention) after fractionation of the microbial bacterial oil in the present invention has a transparent time of more than 120 hours at 10°C.

The liquid oil of the microbial oil obtained after fractionation has a low melting point and strong frost resistance, and remains liquid in the southern winter. It can be used as a blending oil component or change the inconvenient use of microbial oil in winter, enriching the oil market.

2) The process of the method is simple and does not require complex equipment.

Compared with the dry fractionation method, the invention has the advantages of short production period, high separation efficiency and easy control of the production process; compared with the solvent fractionation method, no organic solvent is needed, so it is safe, has less equipment investment and lower cost.

3) The liquid oil (product) quality of microbial oil is better, the yield of liquid oil is relatively high, and there is no pollution of any organic solvent;

4) The surfactant used in the process can be recycled and reused;

5) Since no complex equipment and no organic solvent are needed, a large amount of equipment investment and operating costs are saved, thereby reducing production costs and being suitable for industrial production.

Description of drawings

Fig. 1 is a process flow diagram of the present invention.

Detailed ways

In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the content of the present invention is not limited to the following examples.

Example 1:

As shown in Figure 1, a kind of fractionation method of microbial oil, it comprises the steps:

1) Homogenization: Stir the microbial oil to be fractionated evenly;

2) Crystal breaking: Melt the evenly stirred microbial oil and heat it up to above the melting point of solid fat (25°C) and keep it for 5 minutes;

3) Frozen crystallization: The microbial oil after step 2) is fully crystallized at a low temperature of 4°C for 5 hours, and then placed in a low-temperature constant temperature water bath at 10°C for 2 hours to obtain a viscous slurry containing solid crystals (at this time, the oil material After cooling and freezing, a viscous slurry containing solid crystals is formed);

4) Adding of surfactant solution: press the viscous slurry containing solid crystals: the volume ratio of surfactant aqueous solution=1:1, select the viscous slurry containing solid crystals and aqueous surfactant solution; wherein, surface active The aqueous agent solution is made up of surfactant, inorganic salt and water, and the concentration of surfactant is 0.4wt%, and the concentration of inorganic salt is 1wt%;

The surfactant is sodium dodecyl sulfate (SDS); the inorganic salt is magnesium sulfate (MgSO ₄ );

Add an aqueous surfactant solution to the viscous slurry containing solid crystals, and stir for 0.5 hours to obtain an emulsion system;

5) Liquid oil obtained by centrifugation: put the emulsion system in step 4) at a low temperature of 10°C for 0.5h, centrifuge in a refrigerated centrifuge, and the liquid component will be separated with a light phase (abbreviated as liquid oil in Figure 1 ), adding water to wash and then dehydrating and drying (drying at 20° C. for 6 hours) to obtain liquid oil of microbial oil (product, yield 59.9%);

The aqueous surfactant solution with solid crystals suspended is separated out with the heavy phase (it is a solid-phase oil mixture);

6) Obtain solid fat after demulsification: After taking out the liquid oil (i.e. the liquid component) of the microbial oil, the obtained solid-phase oil mixture is heated at 90°C for 2-10 minutes to demulsify, crystallize and melt, and the solid component is mixed with water Separate the phases, remove the lower water phase to obtain the solid fat component, add water to wash to remove the residual surfactant aqueous solution, and after dehydration and drying, obtain the solid stearin of microbial oil (abbreviated as solid fat in Figure 1). The remaining solution is the surfactant solution, which is recovered and reused.

The liquid oil of microbial bacterial oil after separation in this embodiment can be transparent for more than 120 hours at 10°C (see Table 1 for its physical and chemical indicators). It shows that the liquid oil of the microbial oil proposed by this method is not easy to solidify when the temperature is low (10-20°C).

Example 2:

A fractionation method of microbial oil, it comprises the steps:

1) Homogenization: Stir the microbial oil to be fractionated evenly;

2) Crystal breaking: Melt the uniformly stirred microbial oil and heat it up to above the melting point of solid fat (30°C) and keep it for 5 minutes;

3) Freeze crystallization: The microbial oil is fully crystallized at 4°C for 5 hours, and then placed in a low-temperature constant temperature water bath at 10°C for 2 hours to obtain a viscous slurry containing solid crystals (at this time, the oil material has been cooled and frozen to form a viscous slurry containing solid crystals);

4) Adding of surfactant solution: press the viscous slurry containing solid crystals: the volume ratio of surfactant aqueous solution=1:1, select the viscous slurry containing solid crystals and aqueous surfactant solution; wherein, surface active The aqueous agent solution is made up of surfactant, inorganic salt and water, and the concentration of surfactant is 0.4wt%, and the concentration of inorganic salt is 2wt%;

The surfactant is sodium dodecyl sulfate (SDS); the inorganic salt is magnesium sulfate (MgSO ₄ );

Add an aqueous surfactant solution to the viscous slurry containing solid crystals, and stir for 1.0 h to obtain an emulsion system;

5) Centrifuge to obtain liquid oil: put the emulsion system in step 4) at 10°C for 1 hour, centrifuge in a refrigerated centrifuge, and the liquid component will be separated into a light phase, add water to wash, and then dehydrate and dry ( Dry at 25°C for 6h), to obtain the liquid oil of microbial oil (product, the yield is 57.1%);

The aqueous surfactant solution with solid crystals suspended is separated out with the heavy phase (it is a solid-phase oil mixture);

6) Obtain solid fat after demulsification: After taking out the liquid oil (i.e. the liquid component) of the microbial oil, the obtained solid-phase oil mixture is heated at 90°C for 2-10 minutes to demulsify, crystallize and melt, and the solid component is mixed with water The phases are separated, and the lower water phase is removed to obtain the solid fat component. Water is added to wash to remove the residual surfactant aqueous solution. After dehydration and drying, the solid stearin of microbial oil is obtained.

The liquid oil of microbial bacterial oil after separation in this embodiment can be transparent for more than 120 hours at 10°C (see Table 1 for its physical and chemical indicators). It shows that the liquid oil of the microbial oil proposed by this method is not easy to solidify when the temperature is low (10-20°C).

Example 3:

A fractionation method of microbial oil, it comprises the steps:

1) Homogenization: Stir the microbial oil to be fractionated evenly;

2) Crystal breaking: Melt the uniformly stirred microbial oil and heat it up to above the melting point of solid fat (28°C) and keep it for 5 minutes;

3) Frozen crystallization: The microbial oil is fully crystallized at 4°C for 5 hours, and then placed in a low-temperature constant temperature water bath at 10°C for 2 hours. At this time, the oily material is cooled and frozen to form a viscous slurry containing solid crystals;

4) Adding of surfactant solution: press the viscous slurry containing solid crystals: the volume ratio of surfactant aqueous solution=1: 1.5, select the viscous slurry containing solid crystals and aqueous surfactant solution; wherein, surface active The aqueous agent solution is made up of surfactant, inorganic salt and water, and the concentration of surfactant is 0.4wt%, and the concentration of inorganic salt is 1wt%;

The surfactant is sodium dodecyl sulfate (SDS); the inorganic salt is magnesium sulfate (MgSO ₄ );

Add an aqueous surfactant solution to the viscous slurry containing solid crystals, and stir for 0.8 hours to obtain an emulsion system;

5) Centrifuge to obtain liquid oil: put the emulsion system in step 4) at 10°C for 2 hours, centrifuge in a refrigerated centrifuge, and the liquid component will be separated as a light phase, add water to wash, and then dehydrate and dry ( Dry at 22°C for 4h), to obtain the liquid oil of microbial oil (product, 56.8%);

The aqueous surfactant solution with solid crystals suspended is separated out with the heavy phase (it is a solid-phase oil mixture);

6) Obtain solid fat after demulsification: After taking out the liquid oil (i.e. the liquid component) of the microbial oil, the obtained solid-phase oil mixture is heated at 80°C for 2-10 minutes to demulsify, the crystallization melts, and the solid component is mixed with water The phases are separated, and the lower water phase is removed to obtain the solid fat component. Water is added to wash to remove the residual surfactant aqueous solution. After dehydration and drying, the solid stearin of microbial oil is obtained.

The liquid oil of microbial bacterial oil after separation in this embodiment can be transparent for more than 120 hours at 10°C (see Table 1 for its physical and chemical indicators). It shows that the liquid oil of the microbial oil proposed by this method is not easy to solidify when the temperature is low (10-20°C).

Example 4:

A fractionation method of microbial oil, it comprises the steps:

1) Homogenization: Stir the microbial oil to be fractionated evenly;

2) Crystal breaking: Melt the uniformly stirred microbial oil and heat it up to above the melting point of solid fat (26°C) and keep it for 5 minutes;

3) Freeze crystallization: The microbial oil is fully crystallized at 4°C for 4 hours, and then placed in a low-temperature constant temperature water bath at 10°C for 1 hour. At this time, the oily material is cooled and frozen to form a viscous slurry containing solid crystals;

4) Adding of surfactant solution: press the viscous slurry containing solid crystals: the volume ratio of surfactant aqueous solution=1:0.5, select the viscous slurry containing solid crystals and aqueous surfactant solution; wherein, surface active The aqueous agent solution is made up of surfactant, inorganic salt and water, and the concentration of surfactant is 0.08wt%, and the concentration of inorganic salt is 0.5wt%;

The surfactant is sodium dodecyl sulfate (SDS); the inorganic salt is magnesium sulfate (MgSO ₄ );

Add an aqueous surfactant solution to the viscous slurry containing solid crystals, and stir for 0.6 hours to obtain an emulsion system;

5) Centrifugal separation to obtain liquid oil: put the emulsion system in step 4) at 5°C for 1 hour, centrifuge in a refrigerated centrifuge, the liquid component will be separated as a light phase, add water to wash, and then dehydrate and dry ( 20 ℃ drying 2h), namely the liquid oil of microbial oil (product, the yield is 58.8%);

The aqueous surfactant solution with solid crystals suspended is separated out with the heavy phase (it is a solid-phase oil mixture);

6) Obtain solid fat after demulsification: After taking out the liquid oil (i.e. the liquid component) of the microbial oil, the obtained solid-phase oil mixture is heated at 85°C for 2-10 minutes to demulsify, the crystallization is melted, and the solid component is mixed with water The phases are separated, and the lower water phase is removed to obtain the solid fat component. Water is added to wash to remove the residual surfactant aqueous solution. After dehydration and drying, the solid stearin of microbial oil is obtained.

The liquid oil of microbial bacterial oil after separation in this embodiment can be transparent for more than 120 hours at 10°C (see Table 1 for its physical and chemical indicators). It shows that the liquid oil of the microbial oil proposed by this method is not easy to solidify when the temperature is low (10-20°C).

Example 5:

A fractionation method of microbial oil, it comprises the steps:

1) Homogenization: Stir the microbial oil to be fractionated evenly;

2) Crystal breaking: Melt the evenly stirred microbial oil and heat it up to above the melting point of solid fat (30°C) and keep it for 10 minutes;

3) Freeze crystallization: fully crystallize the microbial oil at 4°C for 7 hours, and then place it in a low-temperature constant temperature water bath at 10°C for 4 hours to obtain a viscous slurry containing solid crystals (at this time, the oil material is cooled and frozen to form a viscous slurry containing solid crystals);

4) Addition of surfactant solution: add an aqueous surfactant solution containing 0.3% SDS and ₁ % MgSO to the slurry according to the oil-water ratio of 1:1, stir well to make the mixed system disperse evenly to form an emulsion system ;

5) Centrifuge to obtain liquid oil: put the emulsion system at 10°C for 0.5h, centrifuge at 5000rpm in a refrigerated centrifuge for 5min, the liquid component will be separated as light phase, add deionized water to wash, and then The liquid oil (yield rate: 57.2%) of microbial oil is obtained by dehydration and drying, and the surfactant aqueous solution with solid crystals suspended is separated with heavy phase;

4) Adding of surfactant solution: press the viscous slurry containing solid crystals: the volume ratio of surfactant aqueous solution=1:2, select the viscous slurry containing solid crystals and aqueous surfactant solution; wherein, surface active The aqueous agent solution is made up of surfactant, inorganic salt and water, and the concentration of surfactant is 0.2wt%, and the concentration of inorganic salt is 3wt%;

The surfactant is sodium dodecyl sulfate (SDS); the inorganic salt is magnesium sulfate (MgSO ₄ );

Add an aqueous surfactant solution to the viscous slurry containing solid crystals, and stir for 1.0 h to obtain an emulsion system;

5) Liquid oil obtained by centrifugation: put the emulsion system in step 4) at a low temperature of 8°C for 5 hours, centrifuge in a refrigerated centrifuge, and the liquid component will be separated as a light phase, add water to wash, and then dehydrate and dry ( 25 ℃ drying 2h), obtain the liquid oil of microbial oil (product, the yield rate is 57.2%);

The aqueous surfactant solution with solid crystals suspended is separated out with the heavy phase (it is a solid-phase oil mixture);

6) Obtain solid fat after demulsification: After taking out the liquid oil (i.e. the liquid component) of the microbial oil, the obtained solid-phase oil mixture is heated at 95°C for 2-10 minutes to demulsify, the crystallization is melted, and the solid component is mixed with water The phases are separated, and the lower water phase is removed to obtain the solid fat component. Water is added to wash to remove the residual surfactant aqueous solution. After dehydration and drying, the solid stearin of microbial oil is obtained.

The liquid oil of microbial bacterial oil after separation in this embodiment can be transparent for more than 120 hours at 10°C (see Table 1 for its physical and chemical indicators). It shows that the liquid oil of the microbial oil proposed by this method is not easy to solidify when the temperature is low (10-20°C).

Example 6

It is basically the same as Example 1, except that the surfactant is sodium alkylbenzene sulfonate. The inorganic salt is sodium sulfate.

The liquid oil of microbial bacterial oil after separation in this embodiment can be transparent for more than 120 hours at 10°C. It shows that the liquid oil of the microbial oil proposed by this method is not easy to solidify when the temperature is low (10-20°C).

Example 7

Substantially the same as Example 1, the difference is that the surfactant is fatty alcohol sodium sulfate. The inorganic salt is aluminum sulfate.

The liquid oil of microbial bacterial oil after separation in this embodiment can be transparent for more than 120 hours at 10°C. It shows that the liquid oil of the microbial oil proposed by this method is not easy to solidify when the temperature is low (10-20°C).

Example 7

It is basically the same as Example 1, except that the surfactant is sodium alkylbenzene sulfonate. The inorganic salt is sodium chloride.

The liquid oil of microbial bacterial oil after separation in this embodiment can be transparent for more than 120 hours at 10°C. It shows that the liquid oil of the microbial oil proposed by this method is not easy to solidify when the temperature is low (10-20°C).

The upper and lower limits of each process parameter (such as temperature, time, etc.) of the present invention, as well as the interval values thereof, can realize the present invention, and the embodiments are not listed here one by one.

Claims (2)

1. a fractionation method of microbial oil is characterized in that it comprises the steps: 1) Homogenization: Stir the microbial oil to be fractionated evenly; 2) Crystal breaking: After heating the uniformly stirred microbial oil to 25-30 °C, keep it warm for 5-10 min; 3) Freezing and crystallization: crystallize the microbial oil after step 2) at 4°C for 4-7 hours, and then place it at a low temperature of 10°C for 1-4 hours to obtain a viscous slurry containing solid crystals; 4) Addition of surfactant solution: According to the volume ratio of viscous slurry containing solid crystals: surfactant aqueous solution = 1:0.5-1:2, select viscous slurry containing solid crystals and aqueous surfactant solution; Wherein, the surfactant aqueous solution is made up of surfactant, inorganic salt and water, and the concentration of surfactant is 0.08-0.4 wt%, and the concentration of inorganic salt is 0.5-3 wt%; The surfactant is sodium lauryl sulfate, sodium alkylbenzenesulfonate or sodium fatty alcohol sulfate; The inorganic salt is magnesium sulfate, sodium sulfate, aluminum sulfate or sodium chloride; Add an aqueous surfactant solution to the viscous slurry containing solid crystals, and stir for 0.5-1.0 hours to obtain an emulsion system; 5) Centrifuge to obtain liquid oil: put the emulsion system in step 4) at a low temperature of 5-10 ℃ for 1-5h, centrifuge in a refrigerated centrifuge, the liquid component will be separated into a light phase, add water to wash After dehydration and drying, the liquid oil of microbial oil can be obtained; The aqueous surfactant solution with solid crystals suspended is separated as a heavy phase to obtain a solid phase oil mixture. 2. The fractionation method of a kind of microbial oil according to claim 1, characterized in that: the obtained solid-phase oil mixture is heated at 80-95°C for 2-10 min, crystallized and melted, and the solid component is Separate from the water phase, take the supernatant, and add water to the obtained solid component to wash to remove the residual surfactant aqueous solution. After dehydration and drying, the solid stearin of microbial oil is obtained.

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