阅读说明：本技术 一种不饱和脂肪酸的提取方法 (Method for extracting unsaturated fatty acid ) 是由 李法宝 于 2019-12-25 设计创作，主要内容包括：本发明提供了一种不饱和脂肪酸的提取方法,属于化学工艺技术领域。该提取方法包括对鱼油原料进行第一次尿素包合：将鱼油原料与乙醇溶液以及尿素混合,随后降温,固液分离,得第一滤液；将第一滤液静置分层,得作为不饱和脂肪酸粗提物的第一下层液。其中,降温采用抽真空方式。通过采用抽真空使部分乙醇挥发来降温,降温时间明显比传统工艺快,乙醇被抽走一部分后,提高了尿素的利用率,从而提高了整个提取工艺的效率,节约了能源。(The invention provides an extraction method of unsaturated fatty acid, belonging to the technical field of chemical processes. The extraction method comprises the following steps of carrying out first urea inclusion on the fish oil raw material: mixing the fish oil raw material with an ethanol solution and urea, then cooling, and carrying out solid-liquid separation to obtain a first filtrate; and standing and layering the first filtrate to obtain a first lower layer solution serving as an unsaturated fatty acid crude extract. Wherein, the cooling adopts a vacuumizing mode. The vacuum pumping is adopted to volatilize part of ethanol to cool, the cooling time is obviously faster than that of the traditional process, and after part of ethanol is pumped away, the utilization rate of urea is improved, so that the efficiency of the whole extraction process is improved, and the energy is saved.)

1. The extraction method of unsaturated fatty acid is characterized by comprising the following steps of carrying out first urea inclusion on a fish oil raw material:

mixing the fish oil raw material with an ethanol solution and urea, then cooling, and carrying out solid-liquid separation to obtain a first filtrate; standing and layering the first filtrate to obtain a first lower layer solution serving as an unsaturated fatty acid crude extract;

wherein, the temperature is reduced to a preset temperature by adopting a vacuumizing mode;

preferably, the vacuum degree is maintained at 2-3KPa in the temperature reduction process;

preferably, the preset temperature is not higher than 10 ℃;

more preferably, the preset temperature is 10 ℃;

preferably, the cooling time is 18-25 min;

preferably, the cooling time is 21 min;

preferably, the fish oil raw material comprises at least one of fish oil of ethyl ester type and fish oil of methyl ester type.

2. The extraction method according to claim 1, further comprising: and (3) sequentially carrying out washing, degassing and adsorption on the unsaturated fatty acid crude extract, and carrying out solid-liquid separation to obtain a filtrate which is the unsaturated fatty acid.

3. The extraction process according to claim 1, further comprising a second urea inclusion: mixing the first subnatant with a new ethanol solution and new urea, cooling, and carrying out solid-liquid separation to obtain a second filtrate; standing and layering the second filtrate to obtain a second subnatant;

preferably, the second subnatant is sequentially subjected to water washing, degassing and adsorption, and solid-liquid separation, and the filtrate is collected.

4. The extraction process according to claim 3, further comprising a new round of extraction of unsaturated fatty acids: the urea produced in the second urea inclusion process is used for carrying out a new round of first urea inclusion on the new fish oil raw material.

5. The extraction method as claimed in claim 4, wherein the urea produced in the second urea inclusion process is mixed with ethanol solution and new fish oil raw material, cooled, and subjected to solid-liquid separation to obtain a third filtrate; standing and layering the third filtrate to obtain a third subnatant;

preferably, the ethanol solution mixed with the new fish oil raw material comprises a first ethanol solution and a second ethanol solution, wherein the first ethanol solution is a first upper layer solution obtained after the first filtrate is subjected to standing and layering in the previous round of extraction of unsaturated fatty acids, and the second ethanol solution is additionally supplemented new ethanol solution;

preferably, the third lower layer liquid is washed with water, degassed, adsorbed, and subjected to solid-liquid separation in sequence, and the filtrate is collected.

6. The extraction process according to claim 1 or 3, characterized in that the concentration of ethanol in the ethanol solution is not less than 90 vt%;

preferably, the ethanol solution is an ethanol-water solution with the ethanol concentration of 95vt percent;

preferably, the amount of said ethanol solution used per g of said urea is higher than 2.5 mL;

more preferably, the amount of said ethanol solution used per g of said urea is 2.7-3 mL;

even more preferably, the amount of said ethanol solution used per g of said urea is 2.7 mL.

7. The extraction process according to claim 1, characterized in that the urea is mixed with the ethanol solution before being mixed with the fish oil feedstock;

preferably, the urea is mixed with the ethanol solution at the temperature of 77-79 ℃;

more preferably, the urea is mixed with the ethanol solution at 78 ℃.

8. The extraction method according to claim 2, characterized in that the water washing comprises: mixing the first lower layer liquid with water, standing at 78-82 deg.C for at least 12min, and removing the lower layer water after standing and layering;

preferably, standing for 15min at 80 ℃;

preferably, the volume ratio of the first underflow to the water is 100: 8-12;

preferably, the water is soft water.

9. The extraction method according to claim 8, wherein degassing comprises: heating the washed material to at least 98 ℃ under a vacuum condition, and degassing for at least 25 min;

preferably, the washed mass is warmed to 100 ℃ under vacuum, followed by degassing for 30 min.

10. The extraction method according to claim 9, wherein the adsorption comprises: mixing the degassed material with an adsorbent, heating to at least 78 ℃ under vacuum, and subsequently removing impurities from the degassed material;

preferably, the temperature is raised to 80 ℃ in the adsorption process;

preferably, the adsorbent comprises at least one of activated carbon and clay;

preferably, the adsorbent comprises, by mass, 1-1.2: 0.8 to 1 of said activated carbon and said clay;

preferably, the adsorbent comprises a mixture of, by mass, 1: 1, said activated carbon and said clay;

preferably, the adsorption time is 18-22min, more preferably 20 min.

Technical Field

The invention relates to the technical field of chemical processes, and particularly relates to an extraction method of unsaturated fatty acid.

Background

The deep sea fish oil contains rich unsaturated fatty acid, wherein the EPA has the functions of inhibiting platelet coagulation, reducing blood fat, reducing cholesterol and the like, and treating and preventing cardiovascular and cerebrovascular diseases. DHA has the functions of promoting the growth and development of brain cells, improving brain functions, improving memory, preventing and treating senile dementia and the like. Thus, the purification of EPA and DHA from deep sea fish oil has been a research focus.

The existing process for purifying EPA and DHA in deep sea fish oil is generally as follows: firstly, the fish oil is transesterified and generally converted into methyl ester or ethyl ester, and then the content of EPA and DHA in the product is improved by methods such as a solvent low-temperature crystallization method, a supercritical carbon dioxide extraction method, a molecular distillation method, a chromatography method or a urea inclusion method and the like.

However, the existing methods have low production efficiency of EPA and DHA and high energy consumption.

In view of this, the present application is specifically made.

Disclosure of Invention

The first purpose of the invention comprises providing an extraction method of unsaturated fatty acid, which reduces the temperature by volatilizing part of ethanol by vacuum pumping, the temperature reduction time is obviously faster than that of the traditional process, and after part of ethanol is pumped away, the utilization rate of urea is improved, thereby improving the efficiency of the whole extraction process and saving energy.

The technical problem to be solved by the invention is realized by adopting the following technical scheme:

the invention provides an extraction method of unsaturated fatty acid, which comprises the following steps:

carrying out first urea inclusion on the fish oil raw material:

mixing the fish oil raw material with an ethanol solution and urea, then cooling, and carrying out solid-liquid separation to obtain a first filtrate; and standing and layering the first filtrate to obtain a first underflow fish oil raw material serving as an unsaturated fatty acid crude extract.

Wherein, the temperature is reduced to the preset temperature by adopting a vacuumizing mode.

In some embodiments, the vacuum is maintained at 2-3KPa during the cooling process.

In some embodiments, the predetermined temperature is no greater than 10 ℃, preferably 10 ℃.

In some embodiments, the cooling time is 18-25min, preferably 21 min.

In some embodiments, the fish oil feedstock comprises at least one of fish oil of the ethyl ester type and fish oil of the methyl ester type.

In some embodiments, the above extraction method further comprises: and (3) sequentially carrying out water washing, degassing and adsorption on the unsaturated fatty acid crude extract, and carrying out solid-liquid separation to obtain a filtrate which is the unsaturated fatty acid.

In some embodiments, the above extraction method further comprises a second urea inclusion: mixing the first lower layer liquid with a new ethanol solution and new urea, cooling, and carrying out solid-liquid separation to obtain a second filtrate; and standing and layering the second filtrate to obtain a second subnatant.

In some preferred embodiments, the second subnatant is subjected to water washing, degassing and adsorption in sequence, solid-liquid separation, and the filtrate is collected.

In some embodiments, a new round of extraction of unsaturated fatty acids is also included: the urea produced in the second urea inclusion process is used for carrying out a new round of first urea inclusion on the new fish oil raw material.

In some embodiments, the urea produced in the second urea inclusion process is mixed with an ethanol solution and a new fish oil raw material, and the mixture is cooled and subjected to solid-liquid separation to obtain a third filtrate; and standing and layering the third filtrate to obtain a third subnatant.

In some preferred embodiments, the ethanol solution mixed with the new fish oil raw material comprises a first ethanol solution and a second ethanol solution, wherein the first ethanol solution is a first supernatant obtained after the first filtrate is subjected to standing and layering in the previous round of extraction of unsaturated fatty acids, and the second ethanol solution is an additionally supplemented new ethanol solution.

Further, the third lower layer liquid may be sequentially subjected to water washing, degassing, adsorption, solid-liquid separation, and collection of the filtrate.

The recovered urea after the second clathration can be used in a new round without treatment, so that the cost can be reduced, and the waste of resources can be reduced.

In some embodiments, the ethanol solution in ethanol concentration is not less than 90v t%, preferably 95v t% ethanol-water solution.

In some embodiments, the amount of ethanol solution used per g of urea is greater than 2.5 mL; preferably, the amount of ethanol solution used per g of urea is 2.7-3 mL; more preferably, the amount of ethanol solution used per g of urea is 2.7 mL.

In some embodiments, the urea is mixed with the ethanol solution prior to mixing with the fish oil feedstock. Wherein, the urea and the ethanol solution can be mixed at the temperature of 77-79 ℃, and preferably at the temperature of 78 ℃.

In some embodiments, the water washing comprises: mixing the first lower layer liquid with water, standing at 78-82 deg.C for at least 12min, and removing the lower layer water after standing and layering.

In some embodiments, degassing comprises: and (3) heating the washed material to at least 98 ℃ under vacuum, and degassing for at least 25 min.

In some embodiments, the adsorbing comprises: the degassed material is mixed with an adsorbent, heated to at least 78 ℃ under vacuum, and then the impurities in the degassed material are removed.

The method for extracting the unsaturated fatty acid has the beneficial effects that:

according to the extraction method of the unsaturated fatty acid, partial ethanol is volatilized by vacuumizing to cool, the cooling time is obviously faster than that of the traditional process, and after part of ethanol is pumped away, the utilization rate of urea is improved, so that the efficiency of the whole extraction process is improved, and the energy is saved.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The method for extracting unsaturated fatty acids provided in the examples of the present application will be specifically described below.

The extraction method of unsaturated fatty acid provided by the application adopts a urea inclusion method, and the raw materials of urea inclusion mainly comprise: the urea molecules and saturated fatty acid or monounsaturated fatty acid form stable crystal inclusion compound to be separated out in the crystallization process, and the polyvalent unsaturated fatty acid has certain spatial configuration due to more double bonds and bent carbon chains and is not easy to be included by urea. And removing the inclusion compound formed by saturated fatty acid, monounsaturated fatty acid and urea by adopting a filtering method to obtain the polyvalent unsaturated fatty acid with higher purity. It can also be understood that: the crystals of urea are tetrahedron, when the crystals coexist with straight chain fatty acid, the crystals become hexahedral crystals, straight chain saturated fatty acid can enter pipelines of the hexahedral crystals most easily to form urea inclusion compounds, and the unsaturated fatty acid has more double bonds which are difficult to enter the pipelines of the crystals, so that the molecular volume is increased by the double bonds, and the urea inclusion compounds are difficult to form. This property is utilized to filter out crystals formed by saturated fatty acids and monounsaturated fatty acids with urea to obtain unsaturated fatty acids at high concentrations.

The inventor finds that the existing urea inclusion method has several defects: firstly, the traditional urea inclusion is cooled by circulating water and chilled water, the cooling process is particularly slow, and the production efficiency is low. Secondly, the prior urea inclusion has large recovery amount of ethanol and high energy consumption. And thirdly, the urea included by the existing urea is discarded after being deoiled, the urea is not recycled, and the using amount of new urea is large.

In view of this, a new urea inclusion process of the present application is specifically proposed. The extraction method of unsaturated fatty acid provided by the application comprises the following steps of carrying out first urea inclusion on a fish oil raw material:

mixing the fish oil raw material with ethanol solution and urea, then cooling, carrying out solid-liquid separation to obtain first filtrate, and standing and layering the first filtrate to obtain first lower layer liquid (the first lower layer liquid is the unsaturated fatty acid crude extract).

In the application, the fish oil raw material mainly comprises at least one of ethyl ester type fish oil and methyl ester type fish oil, and the ethyl ester type fish oil or the methyl ester type fish oil is obtained by performing transesterification reaction on fish oil (such as deep sea fish oil). Preferably, the fish oil raw material is ethyl ester type fish oil generated by transesterification of deep sea fish oil. The unsaturated fatty acid includes at least one of EPA and DHA.

In the present application, the concentration of ethanol in the ethanol solution is not less than 90 vt%, and for example, the ethanol solution may be an ethanol-water solution having an ethanol concentration of 90 vt%, 92 vt%, 95 vt%, or 98 vt%, or may be absolute ethanol. In some preferred embodiments, the aqueous ethanol solution is preferably a 95 vt% ethanol-water solution.

In the present application, the amount of ethanol solution used per g of urea is higher than 2.5 mL. In some preferred embodiments, the amount of ethanol solution used per g of urea is 2.7-3 mL; in some more preferred embodiments, the amount of ethanol solution used per g of urea is 2.7 mL.

It is worth explaining that under the condition of a certain urea dosage, different dosage of the ethanol solution has obvious difference on the urea utilization rate, thereby influencing the urea inclusion effect. When the dosage of the ethanol solution is too small, the urea can not be completely dissolved; when the amount of the ethanol solution is too large, the urea can be completely dissolved but the utilization rate is reduced. By contrast, urea is not completely dissolved when the amount of ethanol solution used per g of urea is equal to or less than 2.5 mL; when the amount of the ethanol solution used is 2.7-3mL per g of urea, the urea can be completely dissolved, but when the amount of the ethanol solution is 2.7mL, the urea utilization rate is higher than that after 2.7mL, and the cost is lower.

By reference, 200g of fish oil feedstock may correspond to 155-165g (preferably 160g) of urea.

In the present application, the mixing order of the fish oil raw material, the ethanol solution and the urea is preferably referred to as: mixing urea with ethanol solution to dissolve urea completely, and mixing with fish oil material. The mixing of the materials can be carried out in a first reaction vessel.

In some embodiments, urea and ethanol solution can be mixed at 77-79 deg.C (such as 77 deg.C, 77.5 deg.C, 78 deg.C, 78.5 deg.C or 79 deg.C), and the heating process can be performed, for example, by using a heating oil furnace. In some preferred embodiments, the urea is mixed with the ethanol solution at 78 ℃.

It is worth to be noted that, the above mixing temperature exceeds 79 ℃, which exceeds the boiling point of ethanol, the whole system is in boiling state, which is not beneficial to operation; while the urea is not sufficiently dissolved at a temperature lower than 77 ℃.

In this application, the cooling adopts the evacuation mode to take out partial ethanol solution so that the temperature drops to preset temperature, and the equipment that this process corresponds and uses includes the vacuum pump. Preferably, the vacuum degree is kept between 2 and 3KPa during the temperature reduction process. The preset temperature is not higher than 10 deg.c, preferably 10 deg.c. In some embodiments, the ethanol is pumped through a condenser with a portion of the ethanol refluxing, and the vacuum is stopped when the predetermined temperature is reached.

It is worth to be noted that the lower the temperature after cooling, the more the urea is wrapped, and the higher the urea utilization rate is; however, when the temperature is too low, the higher the cost, the lower the feasibility of the operation, and therefore, the preset temperature is preferably set to 10 ℃, at which the utilization rate of urea is high and the overall extraction cost is low.

In the present application, the cooling time (i.e. the time for cooling to the preset temperature) is 18-25min, such as 18min, 20min, 22min or 25 min. In some preferred embodiments, the cooling time is 21 min.

The inventor finds that the vacuumizing cooling mode of the application obviously shortens the cooling time compared with the circulating water (heat transfer) cooling mode in the traditional urea inclusion process, and the content of EPA and DHA in the obtained product is higher. The reason for this may be: according to the traditional cooling mode, when the temperature is reduced to a certain degree, urea crystals begin to be attached to the wall of a bottle (in industrial production, the urea crystals are attached to the wall of a reaction kettle), so that heat transfer of materials is hindered, and the cooling time is long. The vacuumizing cooling is fast in cooling speed, but urea inclusion is not influenced, and the utilization rate of urea is higher on the contrary because a part of ethanol is pumped out due to the vacuumizing cooling, and consequently, crystallized urea is more, so that the urea with the inclusion effect is more, and the content of the product is higher.

Further, the solid-liquid separation is carried out on the cooled material, and the solid-liquid separation can be carried out in a filter. The filtrate after filtration (defined as the first filtrate) was collected and subjected to standing for separation, to obtain a first underflow as a crude extract of unsaturated fatty acids. It is worth noting that when the preset temperature of the temperature reduction is higher than 15 ℃, the first filtrate cannot be layered, so that the subsequent operation cannot be performed.

Further, the crude unsaturated fatty acid extract may be subjected to purification treatment, for example, the layered crude unsaturated fatty acid extract may be sequentially subjected to water washing, degassing and adsorption.

In the present application, the water washing process may include: mixing the first lower layer liquid with water, standing at 78-82 deg.C for at least 12min, and removing the lower layer water after standing and layering. Wherein, the upper layer substance after standing and layering is oil substance, and the lower layer substance (lower layer water) is waste water. It is worth noting that this water washing process can be repeated a plurality of times (e.g., 3 times).

In some preferred embodiments, the first subbing liquid is allowed to stand with water at 80 ℃ for 15 min.

In some preferred embodiments, the water used in the water washing process is soft water

In some embodiments, the volume ratio of the first underiayer liquid to the soft water may be 100: 8-12, i.e., 8-12mL of soft water per 100mL of the first subnatant was used for water washing.

In the present application, degassing may include, for example: the washed material (supernatant) was warmed to at least 98 ℃ under vacuum and then degassed for at least 25 min.

Degassing can be carried out in a reaction kettle, and the vacuum condition can be realized by vacuumizing the reaction kettle by a vacuum pump. In the process, the vacuum degree of the reaction kettle is approximately maintained at 100-300 Pa. The heating can be realized by heating the reaction kettle by a heater.

In some embodiments, degassing comprises heating the water-washed material (supernatant) to 100 ℃ under vacuum followed by degassing for 30 min. Further, the degassed material is cooled to 48-52 deg.C (e.g., 50 deg.C).

In the present application, the adsorption may include, for example: the degassed material is mixed with an adsorbent, heated to at least 78 ℃ under vacuum, and then the impurities in the degassed material are removed.

The adsorption can be carried out in a reaction kettle, and the vacuum condition can be realized by vacuumizing the reaction kettle through a vacuum pump. In the process, the vacuum degree of the reaction kettle is approximately maintained at 100-300 Pa. The heating can be realized by heating the reaction kettle by a heater.

In some embodiments, the temperature of the feed is raised to 80 ℃ during adsorption.

In some embodiments, the sorbent may, for example, but not limited to, include at least one of activated carbon and clay. In some embodiments, the adsorbent comprises both activated carbon and clay, for example, may comprise both in a mass ratio of 1 to 1.2: 0.8-1 of activated carbon and argil. In some preferred embodiments, the adsorbent comprises a mass ratio of 1: 1 and clay.

In some embodiments, the adsorption time may be 18-22min, such as 20 min.

Further, cooling the material to 28-32 deg.C (such as 30 deg.C) after adsorption, filtering for the second time to remove adsorbent and impurities adsorbed on the adsorbent, and collecting filtrate to obtain unsaturated fatty acid, wherein the unsaturated fatty acid is mainly omega-3 unsaturated fatty acid, and the omega-3 unsaturated fatty acid contains EPA and DHA.

Further, the first urea inclusion may be followed by a second urea inclusion: mixing the first lower layer liquid with a new ethanol solution and new urea, cooling, and carrying out solid-liquid separation to obtain a second filtrate; and standing and layering the second filtrate to obtain a second subnatant.

Further, the second lower layer liquid was washed with water, degassed, and adsorbed in this order, followed by solid-liquid separation, and a filtrate (this filtrate is also a purified unsaturated fatty acid) was collected. The washing, degassing, adsorption processes and process conditions of the second subbing liquid can be the same as those of the first subbing liquid, and the first subbing liquid can be replaced by the second subbing liquid.

By performing the inclusion twice with fresh urea, the total amount of EPA and DHA in the resulting unsaturated fatty acids is higher than if only one inclusion was performed.

In this application, the first urea inclusion corresponds to a low content product and the second urea inclusion corresponds to a high content product, where "high" and "low" are comparisons of the total amount of EPA and DHA in the product content.

In addition, some embodiments of the present application also include a new round of extraction of unsaturated fatty acids: the urea produced in the second urea inclusion process is used for carrying out a new round of first urea inclusion on the new fish oil raw material. For example, the urea produced in the second urea inclusion process can be mixed with ethanol solution and new fish oil raw material, and then the mixture is cooled and subjected to solid-liquid separation to obtain third filtrate; and standing and layering the third filtrate to obtain a third subnatant.

The urea with high content products is directly used for inclusion of low content products without treatment, so that the cost for treating the urea is reduced, the use of the urea is reduced, and the urea is really recycled; but also leads the yield of the final product to be higher than that of the traditional process, and leads the omega-3 unsaturated fatty acid required by the product to be better enriched.

It should be noted that, according to actual needs, multiple rounds of extraction of unsaturated fatty acids may be performed continuously, and each round of extraction of unsaturated fatty acids may be performed with reference to the first urea inclusion and the second urea inclusion, and the extraction loops of the previous and subsequent rounds are looped. It can be understood that: and mixing the lower layer liquid obtained by the first urea inclusion of the first round, a new ethanol solution and new urea for carrying out second urea inclusion, wherein the separated urea is used for the first urea inclusion of the second round, the lower layer liquid obtained by layering the filtrate after the second urea inclusion is used for the second urea inclusion of the second round, and the corresponding upper layer liquid is used for the first urea inclusion of the third round. When the number of turns is greater than 3, the above-described processes are sequentially referred to. Wherein, the cooling conditions and the like involved in each urea inclusion process can be the same, and are not described in detail herein.

The features and properties of the present invention are described in further detail below with reference to examples.