DD261805A1 - FISH CONCENTRATE AND MANUFACTURING PROCESS THEREFOR - Google Patents

Abstract

According to the invention fish waste products are used to produce a refined fish oil concentrate which consists of about 25% by weight of eicosapentaenoic acid and 35% by weight of docosahexaenone acid and one residue of unsaturated fatty acid compounds, predominantly in the form of alkyl esters of lower alcohols. They are produced according to the invention by esterifying the fatty / fatty acid fraction of the fish oil product at room temperature with a lower alcohol in an alkaline environment and then precipitating the resulting alkyl ester by an excess of urea at 0C. The precipitated urea fatty acid alkyl ester adduct is separated off. The remainder, which mainly contains the essential v 3 fatty acid esters, is extracted with a solvent and then the solvent is separated off. The resulting concentrate contains v 3 fatty acid alkyl esters.

Description

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Field of application of the invention

The present invention relates to methods of producing a refined fish oil concentrate. In the refining process, cholesterol and useful by-products such as urea adducts of fatty acid compounds are produced in addition to higher unsaturated fatty acids »

According to the invention, the fish oil concentrate is prepared from fish waste products. With the method according to the invention, the fat-soluble fractions of the waste products are processed. However, the method according to the invention can also be used for other refined fish oils, such as those obtained in industry for the production of fish products.

Characteristic of the known state of the art

It is known that waste products from the fish processing industry contain useful products, including: a. Fatty acids, cholesterol, proteins and enzymes. They are either fat-soluble or water-soluble. These waste products are usually referred to as fish guts.

By processing the fish innards, the water-soluble portion, which contains proteine and enzymes, can be separated from the fat-soluble portion. The present invention relates only to the fat-soluble portion of the waste product, but it may also be applied to other refined fish oils, such as those used in the industry

-UZ87- 477559

Production of fish products. Hereinafter referred to as fish oil product.

It is known that certain essential fatty acids have medicinal properties in fish oil and are used for the prevention and treatment of thrombotic diseases, for example in ischemic heart disease. In addition, these compounds lower the cholesterol content of the blood.

Of the fatty acids mentioned, the following may be specified as suitable for the medical purposes mentioned: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Both fatty acids are CJ-3 fatty acids of C-20 and C-22 acids, their nomenclature according to the IUPAC system is:

for eicosapentaenoic acid (EDA)

cis-5,8, ll _t l4,17-eicosapentaenoic acid and for docosahexaenoic acid (DHA) cis-4,7,10, 13,16,19-docosahexaenoic acid ,

which is abbreviated to eicosapentaenoic acid 20:56) 3 and dikosohexyenoic acid 22: 6 6) 3

wherein 20 and 22 indicate the number of C atoms in the molecule of the fatty acid, 5 and 6 denote the number of unsaturated bonds, and 633 indicates that the last unsaturated bond is at a distance of 3 carbon atoms from the position.

Descriptions EPA and 20: 5 CJ 3 for eicosapentaenoic acid and DHA and 22: 6 Q3 for docosahexaenoic acid are used below.

The fat-soluble part of cod liveries usually contains 10-25 % of the essential fatty acid compounds EPA and DHA and 2-4 % cholesterol. The remainder consists mainly of fatty acid compounds having a lower saturation, for example pure fatty acids or their glycerides.

It has long been known that the simplest form for the separation of fatty acids is extraction or distillation when they occur in the form of esters, for example as methyl or ethyl esters. Prior to treatment, greasy waste products from the fish industry must undergo trans-esterification and esterification, for example with methanol to produce fatty acid methyl esters.

This base material is quite suitable for the further separation of essential fatty acid compounds and cholesterol from the remaining, less important fatty acid compounds.

U.S. Patent 4,145,446 discloses a method of precipitating fatty acid compounds in a starting material by urea. The purpose is to obtain a product which contains proteins and fats and is suitable as feed. The production of the urea adduct is brought about by a solution of molten urea at 60-140 ° C, the molten fatty acid or a mixture

of fats heated to a temperature of 105 ⁰ C, so that the ratio of fat / fatty acids to urea is between 40/60 and 60/40 weight units. "

Another patent, SU-PS 950 393, describes a process for the production of cholesterol from, for example, fish waste products by hydrolyzing the fatty acid compounds and converting them to soaps. These are then subjected to trichlorethylene extraction at room temperature, whereby the cholesterol is combined with the trichlorethylene, and this compound is then subjected to further separation.

Also, British Patent 1,240,513 discloses a urea separation process wherein the raw material consists of pure methyl and ethyl esters of C 1-6 fatty acids. The urea precipitation takes place in a neutral environment with an excess of the relevant alcohol. The purpose is to provide the ability to obtain a greater concentration of α-linolenic acid. The above-mentioned fatty acid esters contain no higher fatty acids than C-IS in the form of stearic acid, oleic acid, linoleic acid and linolenic acid, which contain a higher content of α-linolenic acid after urea precipitation and removal of the urea adduct from the rest of the material, as by chromatography was detected.

The higher unsaturated fatty acid compounds 20; 5GJ3 and 22:66) 3 can be concentrated by a method which

in 3P-PS 59-071396 is described, wherein said fatty acids by polar solvents! such as acetone, methyl ethyl ketone, methanol, ethanol and similar solvents, thereby forming a soluble and an insoluble extract. Subsequently, the extract is further treated to obtain essential fatty acid compounds.

Object of the invention

The aim of the invention is to provide a simple and economical process for the separation of the essential fatty acid compounds of cholesterol and the other fatty acid compounds.

Explanation of the essence of the invention

The invention is based on the object of a nonuniform raw material containing marine fatty acids and / or esters of these fatty acids and cholesterol as Hauptkoraponenten after trans-esterification with a lower alcohol and under alkaline conditions to produce a concentrate containing the essential 6 ^ Fatty acid compounds, EPA and DHA, as well as to isolate the cholesterol and urea adduct of the saturated and lower unsaturated fatty acid components, which then form separate product fractions.

According to the invention, it now appears possible in a remarkably simple way to increase the process

to optimize the concentration of C03 fatty acid compounds and cholesterol.

According to a fractional precipitation of the less interesting fatty acid compounds with urea, since urea tends to form an adduct with fatty acids that do not belong to the ü) 3-type »Cholesterol also forms no adduct with urea, The previously used method was that Fatty acid compounds to isolate before they were esterified separately, and then subjected to a fractional precipitation with urea. This method is no longer necessary in the present invention.

A particular feature of this method is that fatty acid compounds are not formed prior to the precipitation of the urea, but are precipitated from the same non-uniform mixture of components which form the starting material.

Another particular feature is that the precipitation of the urea takes place in an alkaline environment, in a manner that the alkaline environment is created by the fact that the base only in catalytic amounts such as catalytic agent for the trans-esterification of glycerides Methyl esters and not as a saponification agent for fatty acids,

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A third special feature is that transesterification takes place at room temperature.

The result of trans-esterification at low temperature and in a low alkalinity environment is that the isomerization of double compounds is avoided, resulting in a more uniform product with no toxic effect. At the same time, transconfigurations are avoided. The remaining solution is then extracted with nonpolar solvents, including hexane , to yield both (*) 3 fatty acids and cholesterol in the hexane phase.

Subsequently, the non-polar phase is subjected to evaporation of the hexane under moderate conditions, for example by vacuum distillation. The remaining 6J3 concentrate now contains all the cholesterol, and it is evident that the cholesterol in this concentrate does not readily dissolve and crystallize on cooling , The residual concentrate td 3 - according to the simplified method of the present invention comprises 20 - 30 parts by weight 9S EPA and 35 - 50 wt -.% DHA. The remainder consists predominantly of non-essential fatty acid compounds and is not important for the present purpose.

For a better understanding of the invention, reference is made to the block diagram in FIG. 1, wherein each block represents one step in the process and is identified by a reference numeral. The flow of material to and from each block and between the blocks is indicated by solid and dashed lines. In addition, each material is indicated by a letter.

The starting material is fat and / or fatty acids of

Fish, and in particular fat and / or fatty acids obtained by the fish processing industry in conjunction with silage or autocatalysis processes, may also be used for other forms of marine fat. This greasy starting material is referred to in the claims as a fish oil product »

These fats / fatty acids have a high content of saturated, unsaturated and polyunsaturated fatty acids with a chain length of C18, C20 and C22 as well as a certain amount of cholesterol, vitamins and other fat-soluble substances which are indefinable, usually characterized as non-verifiable and fatty acids with a lower chain length »

Block 1

Fat / fatty acids A of fish containing, inter alia, cholesterol, referred to as fish oil product, were placed in a container x: ur trans esterification with a low boiling point alcohol B, for example, methynol or ethanol, preferably methanol, and a catalytic Agents and auxiliary compounds C, to achieve faster esterification and trans-esterification, avoiding oxidation and discoloration. Potassium hydroxide can be used as the catalytic agent, and small quantities of the sodium salt of ethylenediaminetetraacetic acid (EDDT-Na ₃ ) can be added to avoid oxidation, especially if heavy metals are present, for example chromium, iron, cobalt, nickel and copper.

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The esterification and the trans-esterification are carried out under moderate conditions and stirring at about 20 C over the course of a few hours. The formation of alkyl esters is nearly complete when the ester product has changed its appearance from opalescent to clear. The clear solution Dl thus contains alkyl esters of fatty acids, glycerol, alkanol and some water from the esterification of free fatty acids »

Block 2

The clear solution Dl is then heated to a temperature of 65 to 68 ⁰ C, whereupon a fixed amount of urea E and alkanol B is added and stirred until everything has completely dissolved. The amount of urea E depends on the composition of the fatty acids so that urea E is added in a ratio of 3 parts urea to 1 part alkyl ester (both parts by weight) if the starting material A contains 6-8% by weight EPA * Um to ensure that the components are completely soluble, 9 parts by weight of alkanol B are added.

When everything is dissolved, the solution is slowly cooled to about 20 ⁰ C. An adduct of fatty acid ester F is crystallized and then removed, for example, by decanting and filtering, whereupon the filter mass is cooled to ⁰ ° C. in order to crystallize a greater part of the adduct F. The adduct F is then separated by a method known in the art such that the remaining filter mass G contains the essential fatty acid fractions and the non-saponifiable fractions.

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Block 3,

The slightly alkaline filter mass G is saturated with hexane and extracted with this solvent by a known method, for example by a continuous liquid-liquid countercurrent method , whereupon a further quantity of the adduct of urea ester can be crystallized. "With this extraction two liquids are obtained consisting of hexane H and a residue K.

Block 4

The hexane extract I, which contains the fatty acid esters of polyunsaturated fatty acids 18: 4U3, 20: 5 ^ 3 and 22: 6 CjZ and cholesterol as the main components, is washed in dilute hydrochloric acid L to obtain possible potassium soaps of the polyunsaturated essential fatty acids in the hexane extract to neutralize. The washing water is decanted.

Thereafter, hexane H is removed by evaporation of the extract I to obtain a concentrate free of solvents N containing the compounds important to the invention, the fatty acid compounds EPA and DHA and cholesterol.

The dehydrated extract normally contains 20 - 30 % EPA, 35 - 45 % DHA, 10 - 20 % other polyunsaturated fatty acids and 5 - 15 % cholesterol and the undefined compounds, all units of weight, but the composition is of the type of fish used, the time of the day

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fishing and the type and condition of the source material,

Block 5

The concentrate of alkyl fatty N is then cooled to about -25 ⁰ C, followed by cholesterol O is crystallized "That is centrifuged / filtered. Further impurities present in concentrate N can be removed by cooling the mixture to a temperature below -25 C, whereupon certain undefined compounds are precipitated and filtered by a known method. The remaining CO 3 concentrate (P) thus contains 25-35 % EPA, 35-50 % DHA and 15-25 % other polyunsaturated CJ3 fatty acids (all units by weight) and unsaturated fatty acid compounds which are not essential to the invention.

Product P containing the alkyl esters of the corresponding CJ3 fatty acids may be used as such, or the concentration of EPA and DHA may be increased.

Since the product contains only small amounts of other fatty acids with the same chain length as EPA and DHA, it is well suited for the separation of the essential fatty acids EPA and DHA by means of supercritical fluid extraction.

Another method of increasing the concentration is to perform a preparative liquid chromatography, this method gives a purity of the essential fatty acids of more than 90 %,

- 12 block 6

The alkaline residue K is acidified with concentrated hydrochloric acid L to a pH of 2, whereupon a hexane fraction R is precipitated in an upper layer, which is separated. You can the acidic solution K; Also subject L to further extraction with hexane H, if necessary, whereupon the hexane extracts are collected. The hexane fractions R contain free fatty acids as well as some of their alkyl esters, and quite high percentages of EPA and DHA, but also quite a substantial proportion of C, C 20 and C 22 fatty acids with a lower degree of unsaturation. This acid solution contains water, alcohol, Alkanol, glycerol, urea and other products which can be recovered therefrom by a separate process not described herein.

Block 7

The fatty acid components of the hexane fraction are increased by evaporation of hexane in a separate plant.

Block 8

The remaining solution is esterified using lower alkanols, for example, methanol or ethanol, with a suitable catalytic agent V, which may be, for example, dehydrated hydrochloric acid, acetic acid chloride or boron trichloride.

The resulting alkyl ester D2 from the fatty acid components T from block 7 can be processed in different ways, for example, returned to block 2 for the urea precipitation of the less unsaturated fatty acids.

Working Example

The invention will be explained in more detail below by way of example.

In a reaction vessel, to 50 kg of fish oil product A from cod plants (containing 8% by weight of EPA / 11% by weight of DHA and 2.3% by weight of cholesterol) were added 400 l of methanol B and 10 g of EDTA-Na, C. "Potassium hydroxide dissolved in methanol was added to neutralize aerobic fatty acids in an amount equivalent to a pH 12 pH reaction on wet pH paper. Subsequently, 50 l of methanol B were added.

The whole mixture was stirred for 15 hours at 20 ⁰ C, to effect trans-esterification of the glycerides in Methylester and the esterification of the free fatty acids in Methylester. '

After completion of the trans esterification, the temperature was raised to 65-68 ⁰ C, and 140 kg of urea E and a fixed amount of methanol B were stirred with heating until apparently everything had dissolved. Then the solution was slowly brought to room temperature (approx

 20 C) was cooled, whereupon a urea adduct of fatty acid F was precipitated. It contained most of the saturated and lower unsaturated fatty acid methyl esters.

The urea adduct F was removed from the solution by decanting and filtering according to a conventional, known technique.

nik separated. Result: 100/1 kg urea adduct F.

The solution was then cooled to ^0-4 ° C., allowing a further 5.1 kg of urea adduct F to be filtered out of the solution. «

This filtrate contained polyunsaturated G) 3-fatty acid methyl ester, cholesterol and a residue of undesirable fatty acid fractions with lower unsaturated C21-, C20- and C22-fatty acid methyl esters. To this filtrate was added hexane to saturate, thereby separating a further amount of urea adduct (22 kg) could be. This hexane-saturated solution was extracted in a countercurrent with hexane, so that the hexane extract I was finally about 300 1. The remaining, non-extracted solution is designated K. Subsequently, the hexane extract was evaporated. The yield of ^ O 3 fatty acid methyl ester concentrate was 10.2 kg.

The concentrate containing 23 wt, -% EPA, 41 wt .-% DHA and 8% cholesterol by weight contained, was then cooled to -25 ⁰ C, whereby pure cholesterol O crystallized and was removed by centrifugation, while the residue in the centrifuge with hexane at a low temperature to remove the fatty acid methyl esters from the cholesterol crystals, yield: 760 g of pure cholesterol. The concentrated filtrate P contained 25 wt -.% EPA-Methylester, 43 wt .-% DHA-Methylester, based on the fatty acid portion, and traces of cholesterol.

The above extracted residue K was labeled with a

Rinsed solution of concentrated hydrochloric acid, whereby a hexane phase could be filtered out. Additional hexane was added, stirred and then precipitated. The hexane fractions were combined and the hexane evaporated. To 7.7 kg of the remaining fatty acid and methyl fatty acid fraction was added 15 ml of a 2% methanolic solution of boron trichloride.

earnings; 6 kg Methylfettsäureester to 13 wt -.% EPA-Methylester, 17 wt .-% DHA-Methylester and about 2 wt .-% cholesterol contained.

The methyl fatty acid concentrate containing methanol was recycled to the urea treatment process.

With this invention, it is possible to produce a very pure O 3 concentrate of fatty acid alkyl esters in which the essential antithrombotic fatty acid components, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are present in a high concentration.

In addition, it is possible by the method of the invention to separate very pure and crystalline cholesterol in a very simple way. An additional product is urea-adduct of fatty acid components, but this is not of interest to the invention.

Another advantage of the invention is that it is possible to produce a urea adduct on the basis of the same process in which a trans-ester

tion of glycerides to alkanol esters takes place without the cumbersome process of producing fatty acids, their esterification with alkanol and the subsequent separation by fractional urea precipitation.

By following the process of the invention, it is also possible to avoid the formation of emulsions in the phases, which facilitates the phase separation during the subsequent extraction steps.

Claims (7)

claims 1, refined fish oil concentrate containing alkyl esters of (J 3-eicosapentaenone and docosahexaenoic acid, characterized in that the concentrate consists of at least 25% eicosapentaenoic acid and 35% w / w cocoahexaenoic acid starting from the fatty acid moiety; that the refined fish oil concentrate also contains a residue consisting, inter alia, of other unsaturated fatty acid compounds and that the fatty acid compounds are present predominantly as alkyl esters of lower alcohols. 2 * Refined fish oil concentrate according to claim 1, characterized in 'that the alkyl esters of the fatty acids mentioned are preferably Methylester, 3 «Procedure for the preparation of a refined fish oil concentrate £ fn; The fatty acid / fatty acid fraction of the fish oil product is esterified and / or trans-esterified at room temperature with a lower alcohol in an alkaline environment and the resulting alkyl ester is then subjected to fractional precipitation by excess urea in is subjected to an alkanol and that this precipitation is carried out by cooling the mixture to OC, after it had been heated to 55-90 C by a known method, after which the precipitated urea-fatty acid alkyl ester adduct is separated * and that the remainder, which now predominantly the essential 0 ^ 3 fatty acid ester and the non-saponifiable part Part, then by a known method with a solvent for CO 3 fatty acid alkyl ester and the non-saponifiable part is extracted, after which the solvent is removed after a preliminary rinse of the extract with a water-soluble, dilute acid »so that the resulting concentrate together with the £ 03 fatty acid alkyl esters and the non-saponifiable part is cooled for the crystallization of cholesterol and other undefined, unsaponifiable compounds. 4. A process for the preparation of a refined fish oil concentrate according to claim 3, characterized in that the fatty acid alkyl esters are treated with urea at a temperature which is preferably between 60 and 80 ⁰ C, so that the urea-Fettsäurealkylesteraddukt substantially no CJ 3 fatty acid compounds and non-saponifiable compounds. 5 »A process for the production of a refined fish oil concentrate according to claim A * characterized in that the solvent for the & 3 -fatty acid alkyl ester and the non-saponifiable part is hexane» 6, A process for the preparation of a refined fish oil concentrate according to claim 4, characterized in that the hexane extract is rinsed with a dilute acid, preferably hydrochloric acid, 7 »Procedure for the production of a refined fish -43 Oil concentrate according to claim 4, characterized in that the 0i 3- Fettsäurealkylesterkonzentrat is cooled after removal of the solvent to a temperature not lower than -25 ⁰ C, whereby cholesterol is crystallized, and then to -50 ⁰ G, whereby the
remaining part of the non-saponifiable compounds is precipitated,