WO2012052848A1

WO2012052848A1 - Concentration of polyunsaturated fatty acids by distillation using removable isovolatile co-distilling agents

Info

Publication number: WO2012052848A1
Application number: PCT/IB2011/002881
Authority: WO
Inventors: Asgeir Saebo
Original assignee: Innolipid, As
Priority date: 2010-10-21
Filing date: 2011-10-20
Publication date: 2012-04-26

Abstract

The present invention relates to processes for concentrating polyunsaturated fatty acids, and in particular to concentration of polyunsaturated fatty acids by distillation with removable, isovolatile co-distilling agents.

Description

CONCENTRATION OF POLYUNSATURATED FATTY ACIDS BY DISTILLATION USING REMOVABLE ISOVOLATILE CO-DISTILLING

AGENTS

CROSS-REFERENCE TO RELATED APPLICATION

The present invention claims priority to pending U.S. Provisional Patent Application No. 61/405,380, filed October 21, 2010, the contents of which are incorporated by reference in its entirety.

Field of the Invention The present invention relates to processes for concentrating polyunsaturated fatty acids, and in particular to concentration of polyunsaturated fatty acids by distillation with removable, isovolatile co-distilling agents.

Background of the Invention

Highly unsaturated long chain fatty acids cannot be distilled in conventional high plate number distillation due to formation of trans isomers at high temperatures. Therefore, molecular, or short path distillation, has been the method of choice for purification of such fatty acids. The holdup time of the fatty acids or esters thereof is very short in this distillation technology, and therefore formation of trans isomers are very low (less than 0.1%). The drawback of the technology is the limited number of the so called "theoretical plates," limiting the separating power. Therefore, a full separation of fatty acids with different carbon numbers cannot be achieved.

Accordingly, additional techniques have been used in addition to molecular distillation to enhance the concentration of desired fatty acids. Popular among those are use of enzymes and use of urea complexation. Immobilized enzymes are available commercially that can esterify fatty acids to glycerol or other alcohols. Some types of enzymes react much more rapidly with saturated or oligo unsaturated fatty acids than with polyunsaturated fatty acids. Therefore, by optimization of this technology, a reaction mixture can be achieved where long chain highly unsaturated fatty acids can be concentrated as free fatty acids (not yet esterified) whereas the other fatty acids in the mixture exist as monoacylglycerol or even diacylglycerols. By a subsequent molecular distillation step, the free acids can be collected from the mixture as a distillate.

Urea fractionation or complexation is another popular technique. This technology take advantage of the fact that saturated and oligounsaturated fatty acids more readily forms a precipitating complex when allowed to cool down from a homogenous mixture comprising, fatty acids and urea and methanol or ethanol as a solvent. The precipitation can be filtered off, and methanol and urea removed from the mixture to yield a fatty acid concentrate of highly unsaturated fatty acids.

Combining the techniques above can give a very high concentration of desired fatty acids. However, in order to reach a pure concentration of a single highly unsaturated acids, an additional purification step has up until now been necessary, namely some sort of chromatography. This can either be flash chromatography or high pressure chromatography, also including use of supercritical carbon dioxide as a solvent. The chromatography step is expensive and difficult to scale up. Summary of the Invention

In some embodiments, the present invention provides processes for purification of a polyunsaturated fatty acid or derivative thereof comprising 1) providing a monoester or a free fatty acid concentrate containing at least first and second fatty acids or derivative thereof to be separated; 2) adding, before or after a preconcentration of said first and second fatty acids or derivatives thereof, a co-distilling agent having a volatility approximately the same as one of said first and second fatty acids or derivatives thereof; 3) distilling said mixture; and 4) removing residual amounts of said co-distilling agent from said mixture by a process other than distillation as performed in Step 3. In some embodiments, the processes further comprise repeating steps 2, 3, 4 until the relative concentration of one of said at least first and second fatty acids or derivatives thereof is reduced to a desired level. In some embodiments, the desired level or the relative concentration is selected from the group consisting of a level less than about 10%, 5%, 2%, 1%, 0.5%, and 0.1 % of said mixture on w/w basis.

In some embodiments, the first fatty acid or derivative thereof is one of EPA and DHA and said second fatty acid or derivative thereof is the other of EPA and DHA and said co-distilling agent is a free fatty acid or derivative thereof having a volatility approximately the same as either EPA or DHA and wherein the relative concentration of one of said EPA or DHA is increased as compared to the other. In some embodiments, the first fatty acid or derivative thereof is a polyunsaturated fatty acid or derivative thereof selected from the group consisting of EPA and DHA and a combination thereof and said second fatty acid or derivative thereof is a fatty acid or derivative thereof other than EPA and DHA, said co-distilling agent has a volatility approximately the same as said second fatty acid or derivative thereof, and wherein the relative concentration of said first fatty acid or derivative thereof is increased as compared to said second fatty acid or derivative thereof. In some embodiments, the second fatty acid or derivative thereof is selected from the group consisting of arachidonic acid (ARA) or stearidonic acid (SDA) or a combination thereof, and said co-distilling agent has a volatility approximately the same as a fatty acid or derivative thereof of arachidonic acid (ARA) or stearidonic acid (SDA) so that said ARA or SDA is distilled off with the co-distilling agent. In some embodiments, the first and second fatty acids or derivatives thereof are unsaturated fatty acids with a chain length of from 14 carbons to 24 carbons. In some embodiments, the first and second fatty acids or derivatives thereof are provided as free fatty acids, methyl esters, or ethyl esters. In some embodiments, the co-distilling agent is a free fatty acid or an ethyl ester or a mixture thereof. In some embodiments, the co-distilling agent is an ester of an alcohol and a fatty acid, both having a of chain length of between 4 and 16 carbons. In some embodiments, the co-distilling agent is an ester of methanol, ethanol, propanol, butanol or propylene-glycol or glycerol or any combination thereof. In some embodiments, the co-distilling agent comprises hydrogenated or partially hydrogenated fatty acids or esters thereof. In some embodiments, a process other than distillation as performed in Step 3 is selected from the group consisting of urea complexation, low temperature crystallization with or without a solvent, enzymatic hydrolysis or esterification, supercritical extraction, cold filtration and a combination of enzymatic treatment and molecular distillation. In some embodiments, the present invention provides a food, dietary supplement product or pharmaceutical product containing a polyunsaturated fatty acid purified according to any of the processes described above.

Detailed Description of the Invention The invention herein disclosed renders use of chromatography for purification of unsaturated fatty acids superfluous, thus providing a cost-efficient and scalable process for polyunsaturated fatty acid concentration. In preferred embodiments, the present invention provides processes for concentration of polyunsaturated fatty acids by distillation with removable, isovolatile co-distilling agents. A blend of fatty acids obtained from a natural source that is subjected to distillation for concentration of desired fatty acids typically contain fatty acids of chain length that increase by two and two carbons. Thus, a fish oil contains typically fatty acids of 14, 16, 18 and 22 carbons and only traces of odd chain carbon fatty acids. In a molecular distillation process, the shorter fatty acids have a higher vapor pressure and can to a certain degree be removed from the mixture. However, there will be a limit of the separating power in the distillation technique. If a model mixture of only two fatty acids (e.g., a 16 carbon fatty acid (CI 6) and an 18 carbon fatty acid (CI 8)) is distilled, there will be a limit of how much of the 16C fatty acid can be removed before the 18C fatty acid. This is due to the increasing relative concentration the 18C fatty acid which will eventually be removed at the same quantity at the 16C fatty acid. At a relative concentration of approximately 0.3 (this depends on equipment design, flow relative to evaporation surface and percentage of distillate collected), no more C16 can be removed relatively compared to CI 8.

In some embodiments, a co-distilling agent is utilized to solve this problem, resulting in the removal of higher amounts of a target fatty acid (e.g., a C12, C14, C16, or C18 fatty acid) from a mixture of fatty acids (e.g., refined or unrefined fish or other marine oil, plant or seed oil, or algal oil). In some preferred embodiments, a co-distilling agent is added to a mixture of fatty acids that contains a target fatty acid. The amount of co-distilling agent may be added in a concentration ratio ranging from about 0.1 : 1 to 10 : 1 of the co-distilling agen target fatty acid on a weight/weight (w/w) basis, preferably in a ratio of from about 0.5: to 5: 1 of the co-distilling agenttarget fatty acid on a w/w basis, and most preferably in about a 1 : 1 w/w ratio of the co-distilling agen target fatty acid. In some embodiments, the co-distilling agent has a similar or identical vapor pressure to the target fatty acid and can be removed by a process other than distillation. In some preferred embodiments, the co-distilling agent is another fatty acid which has these properties. In some embodiments, the mixture containing the target fatty acid and co-distilling agent is distilled to provide a mixture with a desired relative concentration (e.g., about 0.05 to about .5, preferably about 0.3) of the target fatty acid and co-distilling agent. In some embodiments, the co-distilling agent is then removed by a technique other than distillation. This step results in a reduction of the relative concentration of the target fatty acid in the mixture. For example, if the co-distilling agent and target fatty acid are reduced to a relative concentration in the mixture of about 0.3, removal of the co-distilling agent will result in a decrease of the relative concentration of the target fatty acid to about 0.15 in the mixture. In some preferred embodiments, these steps are repeated to provide an even greater reduction in the relative amount of the target fatty acid. In some embodiments, the co-distilling agent is re-added to the fatty acid mixture resulting from the removal of the co-distilling agent in the first iteration of the process and the distillation and removal processes are repeated. For example, if addition of the co-distilling agent is repeated and distilled once again, a relative concentration of 0.075 can be achieved. Additional iterations may repeated until a desired relative concentration of the target fatty acid is achieved.

It is contemplated that by repeated additions and distillations, the target fatty acid can be reduced to trace amounts compared to a reference fatty acid in the composition. Accordingly, in some embodiments, the present invention provides methods for reducing the relative concentration of target fatty acid in a mixture of fatty acids by a factor of at least 1.5, 2, 3, 4, 5, 6, 7, 8, 9 or 10 times the amount of reduction that can be achieved by distillation alone. In some embodiments, the amount of the target fatty acid is reduced a trace amount as compared to a reference fatty acid in the mixture. The reference fatty acid may be any fatty acid in the mixture that has a vapor pressure sufficiently different from the co-distilling agent (e.g., a higher vapor pressure) to allow differential distillation and thus removal of the target fatty acid as compared to the reference fatty acid. In some embodiments, the removal of the target fatty acid to a trace amount results in removal of the target fatty acid to an amount of less than 10%, 5%, 2%, 1%, 0.5% or 0.1 % as compared to the reference fatty acid in the mixture.

The present invention is not limited to any particular method for removing the co- distilling agent. In some embodiments, where the co-distilling agent is a fatty acid or ester, urea complexation is utilized to remove the agent. In some embodiments, if the highly unsaturated fatty acid eicosapentaenoic acid, (EPA), is to be separated from highly unsaturated docosahexaenoic acid, (DHA), a fatty acid of low unsaturation, preferably a saturated or a monounsaturated fatty acid of chain length C20, C21 or C22 or a combination thereof is added to the mixture, typically after a pre

concentration of EPA and DHA by distillation. The mixture is again distilled and if desired, the procedure is repeated by adding more monounsaturated fatty acids before another round of distillation is performed. Finally when the desired relative amounts of EPA and DHA is achieved, the added fatty acid or ester is removed by low temperature crystallization or urea fractionation. The distillate, obtained from in this technology, can be converted fully into a stripper mixture for reuse by partial hydrogenation, preferably into a monounsaturated fatty acid mixture.

In another embodiment of the invention, the co-distilling agent can be an ester that can be split and thereafter distilled off is added to the pre concentrated of EPA and DHA mixture. For example a butyl ester of a C 16 acid will comprise 24 carbons and will have a vapor pressure similar to an ethyl ester of a 22 carbon fatty acid. The butyl ester can be added to the pre concentrated mixture and after distillation added another time and then, after another distillation, the relative concentration of EPA to DHA will be reduced. In the next step, the esters are split into free fatty acids and the C 16 is easily removed from the C22 by distillation of the fatty acids or preferably, the mixture should be converted to an ethyl ester before a final distillation.

In yet another embodiment of the technology, the added fatty acid or ester can be removed by a combination of enzymatic treatment and distillation.

The fatty acid compositions produced by the methods described above have a variety of uses. In some embodiments, the present invention provides dietary supplements comprising fatty acids or derivatives thereof. The ingredients of the dietary supplement of this invention are contained in acceptable excipients and/or carriers for oral consumption and preferably include an antioxidant including, but not limited to Controx, Covi-OX, lecithin, and oil soluble forms of vitamin C (ascorbyl palmitate). The actual form of the carrier, and thus, the dietary supplement itself, is not critical. The carrier may be a liquid, gel, gelcap, capsule, powder, solid tablet (coated or non-coated), tea, or the like. The dietary supplement is preferably in the form of a tablet or capsule and most preferably in the form of a soft gelatin capsule. In other embodiments, the supplement is provided as a powder or liquid suitable for adding by the consumer to a food or beverage. For example, in some embodiments, the dietary supplement can be administered to an individual in the form of a powder, for instance to be used by mixing into a beverage, or by stirring into a semi-solid food such as a pudding, topping, sauce, puree, cooked cereal, or salad dressing, for instance, or by otherwise adding to a food.

The dietary supplement may comprise one or more inert ingredients, especially if it is desirable to limit the number of calories added to the diet by the dietary supplement. For example, the dietary supplement of the present invention may also contain optional ingredients including, for example, herbs, vitamins, minerals, enhancers, colorants, sweeteners, flavorants, inert ingredients, and the like. For example, the dietary supplement of the present invention may contain one or more of the following: asorbates (ascorbic acid, mineral ascorbate salts, rose hips, acerola, and the like), dehydroepiandosterone (DHEA), Fo-Ti or Ho Shu Wu (herb common to traditional Asian treatments), Cat's Claw (ancient herbal ingredient), green tea (polyphenols), inositol, kelp, dulse, bioflavinoids, maltodextrin, nettles, niacin, niacinamide, rosemary, selenium, silica (silicon dioxide, silica gel, horsetail, shavegrass, and the like), spirulina, zinc, and the like. Such optional ingredients may be either naturally occurring or concentrated forms.

In some embodiments, the dietary supplements further comprise vitamins and minerals including, but not limited to, calcium phosphate or acetate, tribasic;

potassium phosphate, dibasic; magnesium sulfate or oxide; salt (sodium chloride); potassium chloride or acetate; ascorbic acid; ferric orthophosphate; niacinamide; zinc sulfate or oxide; calcium pantothenate; copper gluconate; riboflavin; beta-carotene; pyridoxine hydrochloride; thiamin mononitrate; folic acid; biotin; chromium chloride or picolonate; potassium iodide; sodium selenate; sodium molybdate; phylloquinone; vitamin D.sub.3; cyanocobalamin; sodium selenite; copper sulfate; vitamin A; vitamin C; inositol; potassium iodide. Suitable dosages for vitamins and minerals may be obtained, for example, by consulting the U.S. RDA guidelines.

Dietary supplements may contain between 0.1 g and 10.0 g of the fatty acids or derivatives thereof, preferably between 0.5 g and 2.0 g of the fatty acids or derivatives thereof, and even more preferably, approximately 1.0 g of the fatty acids or derivatives thereof. The dietary supplements of the present invention may be taken one or more times daily. Preferably, the dietary supplement is administered orally one to two times daily. Frequency of administration will, of course, depend on the dose per unit (capsule or tablet) and the desired level of ingestion. Dose levels/unit can be adjusted to provide the recommended levels of ingredients per day (e.g.,

approximately 1 g of the fatty acids or derivatives thereof) in a reasonable number of units (e.g., two capsules or tablets taken twice a day). In preferred embodiments, the doses add up each day to the daily intake of each ingredient. In preferred

embodiments, the dietary supplements are taken with meals or before meals. In other embodiments, the dietary supplements are not taken with meals.

In other embodiments, the present invention provides nutritional supplements (e.g., energy bars or meal replacement bars or beverages) comprising of the fatty acids or derivatives thereof. The nutritional supplement may serve as meal or snack

replacement and generally provide nutrient calories. Preferably, the nutritional supplements provide carbohydrates, proteins, and fats in balanced amounts. The nutritional supplement can further comprise carbohydrate, simple, medium chain length, or polysaccharides, or a combination thereof. A simple sugar can be chosen for desirable organoleptic properties. Uncooked cornstarch is one example of a complex carbohydrate. If it is desired that it should maintain its high molecular weight structure, it should be included only in food formulations or portions thereof which are not cooked or heat processed since the heat will break down the complex carbohydrate into simple carbohydrates, wherein simple carbohydrates are mono- or disaccharides. The nutritional supplement contains, in one embodiment, combinations of sources of carbohydrate of three levels of chain length (simple, medium and complex; e.g., sucrose, maltodextrins, and uncooked cornstarch). Sources of protein to be incorporated into the nutritional supplement of the invention can be any suitable protein utilized in nutritional formulations and can include whey protein, whey protein concentrate, whey powder, egg, soy flour, soy milk soy protein, soy protein isolate, caseinate (e.g., sodium caseinate, sodium calcium caseinate, calcium caseinate, potassium caseinate), animal and vegetable protein and mixtures thereof. When choosing a protein source, the biological value of the protein should be considered first, with the highest biological values being found in caseinate, whey, lactalbumin, egg albumin and whole egg proteins. In a preferred embodiment, the protein is a combination of whey protein concentrate and calcium caseinate. These proteins have high biological value; that is, they have a high proportion of the essential amino acids. See Modern Nutrition in Health and Disease, eighth edition, Lea & Febiger, publishers, 1986, especially Volume 1, pages 30-32.

The nutritional supplement can also contain other ingredients, such as one or a combination of other vitamins, minerals, antioxidants, fiber and other dietary supplements (e.g., protein, amino acids, choline, lecithin, other fatty acids). Selection of one or several of these ingredients is a matter of formulation, design, consumer preference and end-user. The amounts of these ingredients added to the dietary supplements of this invention are readily known to the skilled artisan. Guidance to such amounts can be provided by the U.S. RDA doses for children and adults. Further vitamins and minerals that can be added include, but are not limited to, calcium phosphate or acetate, tribasic; potassium phosphate, dibasic; magnesium sulfate or oxide; salt (sodium chloride); potassium chloride or acetate; ascorbic acid; ferric orthophosphate; niacinamide; zinc sulfate or oxide; calcium pantothenate; copper gluconate; riboflavin; beta-carotene; pyridoxine hydrochloride; thiamin mononitrate; folic acid; biotin; chromium chloride or picolonate; potassium iodide; sodium selenate; sodium molybdate; phylloquinone; vitamin D.sub.3; cyanocobalamin;

sodium selenite; copper sulfate; vitamin A; vitamin C; inositol; potassium iodide.

Flavors, coloring agents, spices, nuts and the like can be incorporated into the product. Flavorings can be in the form of flavored extracts, volatile oils, chocolate flavorings, peanut butter flavoring, cookie crumbs, crisp rice, vanilla or any commercially available flavoring. Examples of useful flavoring include, but are not limited to, pure anise extract, imitation banana extract, imitation cherry extract, chocolate extract, pure lemon extract, pure orange extract, pure peppermint extract, imitation pineapple extract, imitation rum extract, imitation strawberry extract, or pure vanilla extract; or volatile oils, such as balm oil, bay oil, bergamot oil, cedarwood oil, walnut oil, cherry oil, cinnamon oil, clove oil, or peppermint oil; peanut butter, chocolate flavoring, vanilla cookie crumb, butterscotch or toffee. In one embodiment, the dietary supplement contains cocoa or chocolate.

Emulsifiers may be added for stability of the final product. Examples of suitable emulsifiers include, but are not limited to, lecithin (e.g., from egg or soy), and/or mono- and di-glycerides. Other emulsifiers are readily apparent to the skilled artisan and selection of suitable emulsifier(s) will depend, in part, upon the formulation and final product.

Preservatives may also be added to the nutritional supplement to extend product shelf life. Preferably, preservatives such as potassium sorbate, sodium sorbate, potassium benzoate, sodium benzoate or calcium disodium EDTA are used.

In addition to the carbohydrates described above, the nutritional supplement can contain natural or artificial (preferably low calorie) sweeteners, e.g., saccharides, cyclamates, aspartamine, aspartame, acesulfame K, and/or sorbitol. Such artificial sweeteners can be desirable if the nutritional supplement is intended to be consumed by an overweight or obese individual, or an individual with type II diabetes who is prone to hyperglycemia. The nutritional supplement can be provided in a variety of forms, and by a variety of production methods. In a preferred embodiment, to manufacture a food bar, the liquid ingredients are cooked; the dry ingredients are added with the liquid ingredients in a mixer and mixed until the dough phase is reached; the dough is put into an extruder, and extruded; the extruded dough is cut into appropriate lengths; and the product is cooled. The bars may contain other nutrients and fillers to enhance taste, in addition to the ingredients specifically listed herein.

In still further embodiments, the present invention provides food products, prepared food products, or foodstuffs comprising of the fatty acids or derivatives thereof. For example, in some embodiments, beverages and solid or semi-solid foods comprising the fatty acids or derivatives thereof are provided. These forms can include, but are not limited to, beverages (e.g., soft drinks, milk and other dairy drinks, and diet drinks), baked goods, puddings, dairy products, confections, snack foods, or frozen confections or novelties (e.g., ice cream, milk shakes), prepared frozen meals, candy, snack products (e.g., chips), soups, spreads, sauces, salad dressings, prepared meat products, cheese, yogurt and any other fat or oil containing foods, and food ingredients (e.g., wheat flour).

Claims

Claims What is claimed is:

1. Process for purification of a polyunsaturated fatty acid or derivative thereof comprising

1) providing a monoester or a free fatty acid concentrate containing at least first and second fatty acids or derivative thereof to be separated;

2) adding, before or after a preconcentration of said first and second fatty acids or derivatives thereof, a co-distilling agent having a volatility approximately the same as one of said first and second fatty acids or derivatives thereof;

3) distilling said mixture; and

4) removing residual amounts of said co-distilling agent from said mixture by a process other than distillation as performed in Step 3.

2. Process according to Claim 1, further comprising repeating steps 2, 3, 4 until the relative concentration of one of said at least first and second fatty acids or derivatives thereof is reduced to a desired level.

3. Process of Claim 2, wherein said desired level is selected from the group consisting of a level less than about 10%, 5%, 2%, 1%, 0.5%, and 0.1 % of said mixture on w/w basis.

4. Process of any of Claims 1 to 3, wherein said first fatty acid or derivative thereof is one of EPA and DHA and said second fatty acid or derivative thereof is the other of EPA and DHA and said co-distilling agent is a free fatty acid or derivative thereof having a volatility approximately the same as either EPA or DHA and wherein the relative concentration of one of said EPA or DHA is increased as compared to the other.

5. Process of any of Claims 1 to 3, wherein said first fatty acid or derivative thereof is a polyunsaturated fatty acid or derivative thereof selected from the group consisting of EPA and DHA and a combination thereof and said second fatty acid or derivative thereof is a fatty acid or derivative thereof other than EPA and DHA, said co-distilling agent has a volatility approximately the same as said second fatty acid or derivative thereof, and wherein the relative concentration of said first fatty acid or derivative thereof is increased as compared to said second fatty acid or derivative thereof.

6. Process of any of Claims 1 to 5, wherein said second fatty acid or derivative thereof is selected from the group consisting of arachidonic acid (ARA) or stearidonic acid (SDA) or a combination thereof, and said co-distilling agent has a volatility approximately the same as a fatty acid or derivative thereof of arachidonic acid (ARA) or stearidonic acid (SDA) so that said ARA or SDA is distilled off with the co- distilling agent.

7. Process of any of Claims 1 to 3, wherein said first and second fatty acids or derivatives thereof are unsaturated fatty acids with a chain length of from 14 carbons to 24 carbons.

8. Process of any of Claims 1 to 7, wherein said first and second fatty acids or derivatives thereof are provided as free fatty acids, methyl esters, or ethyl esters.

9. Process of any of Claims 1 to 8, wherein said co-distilling agent is a free fatty acid or an ethyl ester or a mixture thereof.

10. Process of Claims 1 to 3, wherein said co-distilling agent is an ester of an alcohol and a fatty acid, both having a of chain length of between 4 and 16 carbons.

11. Process of any of Claims 1 to 10, wherein said co-distilling agent is an ester of methanol, ethanol, propanol, butanol or propylene-glycol or glycerol or any combination thereof.

12. Process of any of Claims 1 to 11, wherein said co-distilling agent comprises hydrogenated or partially hydrogenated fatty acids or esters thereof.

13. Process of any of Claims 1 to 12, wherein said process other than distillation as performed in Step 3 is selected from the group consisting of urea complexation, low temperature crystallization with or without a solvent, enzymatic hydrolysis or esterification, supercritical extraction, cold filtration and a combination of enzymatic treatment and molecular distillation.

14. A food, dietary supplement product or pharmaceutical product containing a polyunsaturated fatty acid purified according to any of claims 1 to 13.