EP0137862B1 - Process for the preparation of fatty material - Google Patents

Abstract

1. A process for preparation of a fatty substance from pips of fruits of the Ribes genus, characterized by the following steps : a) washing the pips with a polar solvent or a supercritical fluid in a polar condition, b) treating the pips with an antioxidant in order to protect the oil contained therein against oxidation, c) forming the protected pips into flakes, d) pressing the flakes and collecting the oil, e) extracting the rest of the oil from the press cake with a non-polar solvent or a supercritical fluid in a slightly polar condition and the removing the solvent or the supercritical fluid.

Description

The present invention relates to a process for the preparation of fatty substances from fruits of the genus Ribes.

Most vegetable oils contain the polyunsaturated fatty acids linoleic (6,9-octadecadienic) and alpha-linolenic (9,12,15-octadecatrienic). Only the oils from the seeds of hops (Humulus), this hemp (Cannabis), borage (borage) and evening primrose (Oenothera) are known to contain gamma-linolenic acid (6,9,12-octadecatrienic), l evening primrose by being the only source available elsewhere at a high price.

Gamma-linolenic acid is an essential fatty acid which is metabolized by the body into prostaglandins via dihomo-gamma-linolenic acid and arachidonic acid (5,8,11,14-êicosa- tetraene), which is itself a constituent of cell membranes while alpha-linolenic acid does not contribute in the same way to this metabolic process. The conversion of linoleic acid → gamma-linolenic acid in the tissues is incomplete (4-20%) compared to 90-98% for the transformation gamma-linolenic acid - ₇ arachidonic acid) and may even be non-existent (e.g. for the cat) in case of absence or inactivation of the enzyme A-6-desaturase.

A lack of essential fatty acids leads in fact to a nutritional deficiency affecting all the metabolic processes mentioned above and which can lead to biochemical disorders or to organic lesions (e.g. coagulation disorders, dermatological lesions, endocrine disorders, myocardial damage, liver, joint, neurological and mental disorders). We can therefore see the value of a gamma-linolenic acid contribution for the prevention or for the treatment of these anomalies.

Mention has been made of the possibility of using gamma-linolenic and arachidonic acids as therapeutic and nutritional agents p. ex. in FR-A-2197605 and 1603383, gamma-linolenic acid being of synthetic origin or extracted from evening primrose seed oil (Oenothera) or officinal borage (Borage officinalis).

In addition, FR-A-2255055 relates to cosmetic or pharmaceutical compositions based on raspberry seed oil, the anti-inflammatory activity of which is mentioned without indicating its composition. The oil being preferably extracted with chloroform (polar solvent), the anti-inflammatory activity is probably due to the presence of minor components. An analysis of this oil also showed that it contained approximately 54% by weight of linoleic acid and 30% of alpha-linolenic acid but did not contain gamma-linolenic acid.

Finally, Hungarian Patent No. T 13226 mentions that the addition of a ground product or crude oil extracted from paprika seeds, tomatoes or currants to cosmetic products or table oils would inhibit their oxidation. The extraction as provided does not allow the undesirable dyes and waxes to be separated in the products envisaged and the composition of the extract is not mentioned.

It has been found quite surprisingly that the fruit seed oils of the genus Ribes contain a significant percentage, at least 4% by weight of gamma-linolenic acid. In addition, these seeds are available in large quantities in oil cakes from the pressing of fruit juices, the production of jams and jellies or fermentation musts from the production of spirits, liqueurs and schnapps, by-products. which were hitherto used as fuel or as fodder.

According to the invention, the fatty substances come in practice from blackcurrant (Ribes nigrum), currants (Ribes rubrum), gooseberries (Ribes ova-crispa or grossularia) or from hybrid fruits of these species. One can of course use a mixture of these fruits.

The lipid content of the above-mentioned by-products is 12 to 30% by weight depending on the raw material. The lipid phase in turn contains 4 to 19% by weight of gamma-linolenic acid.

As an indication, the seed oil of these fruits consists of triglycerides of the following fatty acids, by weight:

Blackcurrant oil, which is preferred because of its high content of gamma-linolenic acid, also contains 1 to 2% by weight of unsatifiable bodies, such as aliphatic alcohols, hydrocarbons, tocopherols, squalene, P-sitostero , cam- pesterol and A-7 stigmasterol. Its density is 0.9215g / cm ³ (at 20 ° C) and its viscosity 28.3 mPa.s (28.3 centipoise) (at 20 ° C).

• a) on lave les pépins avec un solvant polaire ou un fluide supercritique à l'état polaire et on élimine le solvant ou le fluide supercritique, cette étape étant facultative,
• b) on traite les pépins avec un antioxydant de manière à protéger l'huile qu'ils contiennent de l'oxydation,
• c) on met les pépins protégés sous forme de flocons,
• d) on presse les flocons et on receuille l'huile, e) on extrait l'huile résiduelle du gâteau de pressage avec un solvant non polaire ou un fluide supercritique à l'état faiblement polaire puis on élimine le solvant ou le fluide supercritique.

Le procédé selon l'invention comporte de préférence les étapes supplémentaires suivantes, lesquelles sont indispensables lorsque l'étape a) précédente est supprimée mais constituent une option lorsque l'étape a) est maintenue:

• f) on mélange l'huile de pression et une solution contenant l'huile "résiduelle de l'étape e) puis on neutralise le mélange pour en éliminer les acides gras libres résiduels,
• g) on refroidit le mélange neutralisé, on le laisse décanter et on le filtre,
• h) on décolore le filtrat par un adsorbant puis on élimine le solvant et
• i) on désodorise l'huile.

The invention relates to a method for preparing fatty substances from fruit seeds of the genus Ribes, characterized by the following steps:

• a) the seeds are washed with a polar solvent or a supercritical fluid in the polar state and the solvent or the supercritical fluid is removed, this step being optional,
• b) the seeds are treated with an antioxidant so as to protect the oil which they contain from oxidation,
• c) the protected seeds are put in the form of flakes,
• d) the flakes are pressed and the oil is collected, e) the residual oil is extracted from the pressing cake with a non-polar solvent or a fluid supercritical in the weakly polar state then the solvent or the supercritical fluid is eliminated.

The method according to the invention preferably comprises the following additional steps, which are essential when the previous step a) is deleted but constitute an option when the step a) is maintained:

• f) the pressure oil and a solution containing the residual oil from step e) are mixed, then the mixture is neutralized in order to remove the residual free fatty acids therefrom,
• g) the neutralized mixture is cooled, allowed to settle and filtered,
• h) the filtrate is discolored with an adsorbent and then the solvent is removed and
• i) the oil is deodorized.

According to the invention, the term plant material used means the by-products mentioned above. The raw material is generally in the form of highly colored oil cakes and containing the waxes associated with the seeds, waxes and dyes representing from 5 to 7% by weight of the crude oil that would be extracted therefrom, for example. ex. with hexane. Waxes are saturated and monounsaturated esters of fatty alcohols and long chain fatty acids that are solid at room temperature. The waxes and dyes in question are not desired in an oil constituting the nutritive compositions.

A raw material of choice is the cake for pressing fruit juices, in particular blackcurrants. We dry it first p. ex. in air for about 1 hour at around 60 ° C. It is coarsely ground and sieved, so as to obtain particles of 1 to 1.5 mm, the sieving yield being 60 to 80% of the weight of the cake. It is advantageous to separate the seeds from the straws by gravity in an air stream or "elutriation" with a yield by weight of 80 to 90%.

According to a preferred embodiment of the process, the seeds are washed with a polar solvent in common use so as to rid them of waxes, dyes and free fatty acids. For cosmetic applications, p. ex. methanol, isopropanol, acetone, ethanol or a mixture of these solvents or else a supercritical fluid p. ex. carbon dioxide under conditions which give it a polar character. For food and pharmaceutical applications, an authorized solvent p. ex. ethanol or supercritical carbon dioxide.

By way of example, the seeds are washed with ethanol at reflux, either by batch, p. ex. a first time for approximately 2 hours and a second time for approximately 30-60 minutes, either continuously for approximately Z hours and then wring out the residue.

Alternatively, the seeds can be washed using p. ex. carbon dioxide at 250-350 b and 60-80 ° C in a continuous cycle, the solvent being recovered in gaseous form by reduction of the pressure, recompressed and recycled. It has been found that washing makes it possible to remove most of the coloring matters and waxes present in the films and around the seeds: in fact, the waxes are deposited by cooling from the alcoholic extract while the latter is very strongly colored.

The washed and drained seeds are treated with an antioxidant so as to protect their oil from oxidation during the subsequent stages. As antioxidants, there may be mentioned dilute aqueous solutions of ascorbic or benzolic acid or their sodium or potassium salts, for example an aqueous solution containing 30 to 50 ppm (parts per million) by weight of ascorbic acid, at a rate of 7-8% of the weight of the seeds used.

The protected seeds are pressed p. ex. by means of a continuous screw press under high pressure and up to 90% of the oil contained in the seeds is obtained according to the type of press used, the pressing conditions and the number of pressing cycles applied.

The pressing is followed by solvent extraction from the pressing cake. Protected and dried seeds are flaked on a flattening cylinder. This shaping avoids clogging and facilitates the subsequent extraction of the oil by giving the product porosity allowing good penetration of the solvent, and the flakes in particular resist crushing. The flakes are heated to 80-90 ° C and pressed under a pressure of 490-785 b (500-800 kg / cm ² ), maintaining the temperature of the press head at a value below 90 ° C . In this way, 50 to 60% of the oil contained in the seeds is obtained. The pressing cake has a density of 0.58 to 0.65, about twice the density of the flakes and can be appropriately percolated with the extraction solvent. The pressing cake is ground and the ground residue is extracted.

In this step, the residual oil is extracted with a non-polar solvent, e.g. ex. hexane in an amount of 200 to 250% by weight of hexane relative to the residue. Alternatively, liquid carbon dioxide or preferably supercritical carbon dioxide can also be used in this step, under conditions where it is weakly polar, e.g. ex. at 200-300 bar and 40-60 ° C. One can of course use p. ex. supercritical carbon dioxide in the washing step and in the subsequent extraction step or in only one of these steps, the other being carried out with p. ex. ethanol, respectively hexane.

The pressure oil and the extraction solution are combined. It is possible, although these measures constitute only preferred options, to neutralize the mixture in order to remove the residual free fatty acids, possibly after having partially evaporated the solvent, p. ex. in the case of hexane so that the solution contains approximately 10% by weight of oil, by concentrated sodium or potassium hydroxide (2N), cool it to approximately 0-4 ° C for approximately 24 hours and filter it at this temperature so as to completely eliminate the residual waxes. Likewise, the following discoloration and deodorization are preferred options: lore the solution with an adsorbent p. ex. activated charcoal or activated bleaching earths based on activated aluminum silicate such as montmorillonite or bentonite at a rate of 2-8% by weight relative to the oil used at 20-60 ° C. and then the solvent is evaporated. The oil is then deodorized by steam entrainment at 140-220 ° C and preferably at approximately 180 ° C under a vacuum of 0.75 mb (1 torr) or less.

According to a variant of preparation of the oil, the seeds are not washed beforehand (step a)) but the pressing is carried out directly followed optionally by extraction with a solvent from the pressing cake. In this case, neutralization, elimination of waxes by decantation, discoloration and deodorization as indicated above (steps f) to i)) are essential for obtaining a pale yellow refined oil.

In some cases, it is desired to enrich the fatty substance with gamma-linolenic acid. To do this, the oil freed from waxes and free fatty acids is saponified with an alkali hydroxide, for example potassium hydroxide in methanol / water at a concentration of approximately 11%, the salts obtained are acidified. a mineral acid, e.g. ex. 2N sulfuric acid, the fatty acids liberated by hexane are extracted, the organic phase is separated and dried p. ex. by addition of sodium sulfate. The organic phase is fractionated by high performance liquid chromatography, by passage over columns of silica gel loaded with silver nitrate and elution preferably with a mixture of dichloromethane, toluene and diethyl ether 70/25/5 - 63 / 30/5 in isocratic mode, that is to say with recycling of the solvent mixture of fixed composition and a fraction containing approximately 60% by weight of gamma-linolenic acid and approximately 40% of alpha-linolenic acid is thus obtained. .

Almost pure gamma-linolenic acid can be isolated by performing high performance liquid chromatography with support on the C ₈ or C _{18 side} in reverse phase with gradient of solvent mixture acetonitrile / water, methanol / water or isopropanol / water.

The fatty substances obtained according to the invention can be incorporated into nutritive compositions according to European patent application No. 92085. The following example illustrates the invention. In it the parts and percentages are expressed in weight value unless otherwise indicated.

Example

432 kg of dried blackcurrant pulp are milled from the pressing of the juices in a disc mill and the ground product is sieved so as to obtain 261 kg of particles between 1 and 1.5 mm. We send it to an elutriator and we collect 214 kg of a heavy fraction consisting essentially of seeds. Wash twice with 520 kg of ethanol at reflux each time.

The previously washed seeds are sprayed with 14-16 water containing 30-50 ppm (parts per million) of ascorbic acid. The treated seeds are dried at 70 ° C for 30-40 min and put into the form of flakes using a flattening roller mill. The flakes are heated to 80-90 ° C for 30-40 min. These have a density of 0.35.

The flakes are pressed for 30-50 min in a continuous screw press under a pressure of 500-800 kg / cm ² with a screw rotation speed of 10-20 revolutions / min while maintaining the head temperature of the press at 80-90 ° C. 26-31 kg of oil are thus obtained (approximately 50-60% of the oil present in the seeds). The pressing cake has a density of 0.60 which allows percolation without clogging during the subsequent extraction step. It is ground and extracted with 2 times 370-400 kg of hexane at reflux for 3 h. Then cool and filter. After evaporation of the hexane, 22 to 26 kg of additional oil are thus collected.

Claims (10)

1. A process for preparation of a fatty substance from pips of fruits of the Ribes genus, characterized by the following steps:

a) washing the pips with a polar solvent or a supercritical fluid in a polar condition,

b) treating the pips with an antioxidant in order to protect the oil contained therein against oxidation,

c) forming the protected pips into flakes,

d) pressing the flakes and collecting the oil,

e) extracting the rest of the oil from the press cake with a non-polar solvent or a supercritical fluid in a slightly polar condition and the removing the solvent or the supercritical fluid.

2. A process as claimed in claim 1, characterized by the further following steps:

f) mixing the pressed oil with a solution containing the residual oil of step e) and then neutralizing the mixture in order to eliminate the residual free fatty acids therefrom,

g) cooling the neutralized mixture, letting it settle and filtering it,

h) decolorizing the filtrate with an adsorbent and then removing the solvent and,

i) desodorizing the oil.

3. A process claimed in claim 2, characterized by suppressing step a).

4. A process as claimed in any one of claims 1 to 3, characterized by obtaining the pips by drying the press cake of blackcurrant juices, by milling and sieving it in order to obtain particles of from 1 to 1.5 mm and by separating the pips by elutriation.

5. A process as claimed in claim 1 or 2, characterized by washing the pips with refluxing ethanol.

6. A process as claimed in any one of claims 1 to 3, characterized by pressing the flakes under a pressure of from 490 to 785 b (500-800 kg/cm2) while maintaining the temperature of the press head under 90 °C.

7. A process as claimed in any one of claims 1 to 3, characterized by extracting the press cake with refluxing hexane.

8. A process as claimed in claim 2 or 3, characterized by partially evaporating the non-polar solvent in step

f) to obtain a solution containing 80 to 90% by weight of solvent, neutralizing the solution with a concentrated alkali and by maintaining the solution in step g) at a temperature of 0 °C to 4 °C during about 24 h and filtering it.

9. A process as claimed in claim 2 or 3, characterized by decolorizing the filtrate in step h) with from 2 to 8% of activated adsorbent based on the weight of the fatty substance in solution.

10. A process as claimed in claim 2 or 3, characterized by desodorizing the oil in step i) at a temperature of from 140 °C to 220 °C under a vacuum under 0.75 mb (1 torr).