CN105316113A - Polyunsaturated fatty acid enriching method - Google Patents

Abstract

The invention discloses a method for enriching polyunsaturated fatty acids. Acetonitrile is used as a crystallization solvent to carry out one or more crystallization and separation operations on fatty acid raw materials from fish oil, fish oil by-products, and microbial oils to enrich polyunsaturated fatty acids. unsaturated fatty acid. The method comprises the following steps: (1) the fatty acid is uniformly mixed with a certain volume of acetonitrile, crystallized at a low temperature, solid-liquid separation is carried out after the crystallization, the content of the polyunsaturated fatty acid in the liquid phase can be increased to 50%-90%, and the yield can reach 50%. Above; (2) if the content of polyunsaturated fatty acids needs to be further improved, part of the solvent can be removed from the liquid phase in (1), and multiple low-temperature crystallizations can be carried out, so that the content of polyunsaturated fatty acids can be increased to more than 80%. The method of the invention is simple to operate, the solvent can be recycled, time-saving compared with other solvents for low-temperature crystallization, the polyunsaturated fatty acid content and yield are greatly improved, and can be applied to the preparation of polyunsaturated fatty acid pharmaceutical raw materials.

Description

A method for enriching polyunsaturated fatty acids

technical field

The invention relates to a method for enriching polyunsaturated fatty acids, more specifically, a method for enriching polyunsaturated fatty acids through solvent crystallization.

Background technique

The important role of polyunsaturated fatty acids in human nutrition and disease prevention has been recognized by the scientific community. Numerous studies have reported the health benefits of polyunsaturated fatty acids. Among them, arachidonic acid (ARA) and docosahexaenoic acid (DHA) are not only important components of the neuromembrane system, but also natural fatty acids in breast milk, which are important for the growth of the brain and nervous system of infants. effect. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have good preventive and therapeutic effects on cardiovascular diseases, atherosclerosis, chronic inflammation, and Alzheimer's disease. Since the body cannot directly synthesize or synthesize less omega-3 and omega-6 polyunsaturated fats, they must be supplemented through dietary intake.

The content of polyunsaturated fatty acids in natural oils and fats is relatively low, and polyunsaturated fatty acids with higher purity are required to achieve certain health effects or medicinal effects. Therefore, it is necessary to enrich polyunsaturated fatty acids. Low-temperature crystallization mainly uses the difference in solubility of different fatty acids at different temperatures and in different solvents to separate them. This difference in solubility depends on the chain length and number of double bonds of the fatty acid. When the number of double bonds in the fatty acid is the same, the longer the carbon chain, the lower the solubility; when the length of the carbon chain is constant, the more the number of double bonds, the greater the solubility. Low-temperature crystallization is easy to operate, low in cost, and the solvent can be recycled.

Li He et al. used acetone-ethanol mixed solvents to enrich EPA and DHA in fish oil fatty acids by controlling the crystallization rate. After one separation, the content increased from 7% to 15% to 50% to 58%. Reach 73% to 79% (Li He, Li Peiwen et al. Low-temperature crystallization method for enriching EPA and DHA in fish oil. "China Huayang Medicine", 1997, 4: 50-52). After Li Pengcheng et al. extracted the oil from the marine animal oil-type waste powder, they used 1 to 3 times acetone to place it at -80-0°C for 6-12 hours, and then carried out solid-liquid separation to enrich the content of EPA and DHA (Li Pengcheng, Li Ting et al. A method for extracting natural EPA and DHA. China, 201410015950.1). Traditional solvent low-temperature crystallization mostly uses acetone or n-hexane as the low-temperature crystallization solvent, which takes a lot of time. Generally, it needs to be crystallized at low temperature for more than 10 hours, which reduces the enrichment efficiency. The invention uses acetonitrile as a low-temperature crystallization solvent, greatly shortens the time required for crystallization, retains the advantages of low-temperature crystallization operations, and can significantly improve the purity and yield of polyunsaturated fatty acids, which is suitable for industrial production.

Contents of the invention

The purpose of the present invention is to use acetonitrile as a solvent to carry out one or more crystallization and separation operations on fatty acids from fish oil, fish oil by-products, and microbial oils to enrich the polyunsaturated fatty acids therein.

The technical solution of the present invention is to use fatty acids from fish oil, fish oil by-products and microbial oils as raw materials, fully mix them with a certain amount of acetonitrile, and carry out one or more low-temperature crystallization to enrich polyunsaturated fatty acids. The specific steps are:

(1) Primary low temperature crystallization

Mix fatty acids from fish oil, fish oil by-products, and microbial oils with acetonitrile evenly at a ratio of 1:5 to 1:25 (W/V), place them at -80 to 0°C for low temperature crystallization for 0.5 to 2 hours, and carry out solidification after crystallization. The liquid was separated, and the liquid phase was collected and the solvent was removed under vacuum at 45°C. After the first low-temperature crystallization, the polyunsaturated fatty acid content of the raw material can be increased to 60%-90%, and the actual yield can reach 55%-75%.

(2) multiple low temperature crystallization

If it is necessary to further increase the content of polyunsaturated fatty acids, 1/3~1/2 of the solvent can be removed from the liquid phase after crystallization in the previous step, and the crystallization can be continued at -80~-40°C for 0.5~1h, and the polyunsaturated fatty acids can be further made Unsaturated fatty acid content increased to 90% to 96%.

The invention has the advantages of simple operation, low cost and time saving, and the solvent can be recycled and used. The conditions in the whole operation process are mild, the structure of the polyunsaturated fatty acid will not be damaged, and the purity and yield of the obtained polyunsaturated fatty acid are high, which can be applied to the preparation of raw materials in the early stage of the pharmaceutical industry.

detailed description

In order to better illustrate the content of the present invention, the present invention will be further described below in conjunction with specific examples, and the protection scope of the present invention is not limited to the following examples.

Implementation plan one

Take 50 g of algal oil fatty acid, mix it with 400 ml of acetonitrile at room temperature, and place it in a -40°C refrigerator for low-temperature crystallization for 1.5 h. After the crystallization is completed, the solid-liquid separation is carried out, and the liquid phase is taken to remove acetonitrile at 45° C. to obtain the desired product. Use the gas phase to separate the fatty acid composition of raw materials and products, and calculate the corresponding yield, as shown in the table below:

Table 1 raw material, product polyunsaturated fatty acid composition

Through one crystallization, the polyunsaturated fatty acid content of algae oil can be increased from 57.82% to 90.54%, and the yield can reach 59.76%. Among them, DPA (omega-6) increased from 16.38% to 24.59%, and DHA increased from 38.92% to 61.83%.

Implementation plan two

Take 50g tuna oil fatty acid and mix it with 550ml acetonitrile evenly at room temperature, put the fatty acid-acetonitrile solution in a -40°C refrigerator for 1 hour to perform the first low-temperature crystallization. After the crystallization is complete, solid-liquid separation is carried out, and the liquid phase is taken, and 1/2 of the solvent is removed under vacuum at -45°C, and the new fatty acid-acetonitrile solution is placed in a -80°C refrigerator for the second crystallization for 0.5h. After the crystallization is completed, the second solid-liquid separation is carried out, and the liquid phase is removed from the acetonitrile under vacuum at 45°C to obtain the product. The fatty acid composition of raw materials and products was analyzed by gas phase, and the experimental results are shown in the table below:

Table 2 Raw materials, product fatty acid composition and yield

Through secondary crystallization, the polyunsaturated fatty acid of tuna oil is increased from 37.67% to 89.36%. Among them, EPA increased from 6.71% to 16.47%, and DHA increased from 25.70% to 65.33%.

Implementation plan three

Take 10g of microbial fatty acids rich in ARA (the content of saturated fatty acid is about 30%, the content of monounsaturated fatty acid is about 10%, the content of C18:2 and C18:3 is about 17%, and the content of C20:4 is about 40%) and 100ml of acetonitrile was mixed thoroughly, placed at -20°C for low-temperature crystallization for 1 hour, the solid phase was removed, and the solvent acetonitrile in the liquid phase was removed to obtain the product. The ARA content in the product reaches 70%, and the yield is 60%.

Claims (6)

1. the enriching method of a polyunsaturated fatty acid, utilize the low-temperature solvent crystallization of lipid acid, it is characterized in that utilizing acetonitrile as recrystallisation solvent, one or many crystallization and lock out operation are carried out to lipid acid, through a low temperature crystallization, make content of polyunsaturated fatty acid in raw material be increased to more than 50%, productive rate reaches more than 50%; Through multiple low-temperature crystallization, content of polyunsaturated fatty acid in raw material is made to be increased to more than 80%.

2. the enriching method of a kind of polyunsaturated fatty acid according to claim 1, it is characterized in that, the target polyunsaturated fatty acid carbon chain lengths of described expectation enrichment is at least 20 carbon, double bond number is at least 4, comprise eicosatetraenoic acid (C20:4, ω-6), timnodonic acid (C20:5, ω-3), clupanodonic acid (C22:5, ω-3), clupanodonic acid (C22:5, ω-6), one or more in the lipid acid such as docosahexenoic acid (C22:6, ω-3).

3. the enriching method of a kind of polyunsaturated fatty acid according to claim 1, is characterized in that, described lipid acid comes from fish oil, fish oil by product, microbial oil, and content of polyunsaturated fatty acid is not less than 15%.

4. the enriching method of a kind of polyunsaturated fatty acid according to claim 1, is characterized in that, the ratio of described lipid acid and solvent acetonitrile is 1: 5 ~ 1: 25 (W/V), and Tc is-80 ~ 0 DEG C, and crystallization time is 0.5 ~ 2h.

5. the enriching method of a kind of polyunsaturated fatty acid according to claim 1, is characterized in that, described through a low temperature crystallization, in raw fatty acid, content of polyunsaturated fatty acid can be increased to 60% ~ 90%, and productive rate is 55% ~ 75%.

6. the enriching method of a kind of polyunsaturated fatty acid according to claim 1, is characterized in that, described through multiple low-temperature crystallization, in raw fatty acid, content of polyunsaturated fatty acid can be increased to 80% ~ 96%.