EP0703960B1 - Method of degumming a fatty substance and fatty body so obtained - Google Patents

Abstract

PCT No. PCT/BE94/00041 Sec. 371 Date Feb. 26, 1996 Sec. 102(e) Date Feb. 26, 1996 PCT Filed Jun. 16, 1994Process for degumming a fatty substance such as a crude or delecithinated, animal or vegetable oil or fat, including bringing this fatty substance into contact with an aqueous solution of a complexing agent and of a detergent and/or emulsifier making it possible to hydrate the phospholipids present in the latter, and fatty substance thus obtained.

Description

The present invention relates to a process for degumming a fatty substance, such as oil or fat, animal or vegetable, crude or delecithinate, as well as the fatty substance thus obtained.

All fatty substances contain a certain number of impurities, fat soluble substances entrained when the oil cells burst, which could make it unusable for consumption. Some of these impurities have a harmful influence on the taste, the smell, the appearance of the product, its conservation.

The purpose of refining fatty substances is eliminate free fatty acids, oxidation products, unpleasant aromas, colorings, toxic products (such as pesticides, glycosides) but also phospholipids as well as metals (such than iron, copper) present in trace amounts and generally linked to organic compounds.

The presence of phospholipids in crude oils causes a number of disadvantages. In the presence of water, they hydrate and form deposits that decompose over time. The experience also shows that a poorly disposed refined oil of its phospholipids acidifies, oxidizes and takes quickly an unpleasant taste. Phospholipids are often linked to heavy metals (such as calcium, magnesium, iron, copper), some of which influence detrimental to the conservation of refined fats since they are oxidation catalysts. Phospholipids are also thermally substances unstable which when decomposed at high temperature darken the oil. Finally the phospholipids being surfactants, their incomplete elimination as soon as the start of refining leads to the formation of foam and emulsions with consequent losses abnormal in oil and land deactivation bleaching.

Among the fatty substances, some contain few phospholipids (e.g. palm fat, lauric and animal fats); so they can be easily rid of these substances by a dry degumming, i.e. by adding an acid to break them down and earth to fix them. Thus, these fatty substances can be refined by distillation neutralizing or physical refining.

Oils obtained by pressure and / or by extraction using a solvent (for example soy, rapeseed, sunflower) are very rich in phospholipids and are therefore generally refined chemically. This type of refining presents several disadvantages; among other things, it generates "soapstocks", mixtures of oil and soaps, which must be treated, this which involves oil losses and additional costs.

• Un dégommage acide qui consiste à dissocier le complexe phospholipidique à l'aide d'un acide pour ensuite l'hydrater. Ce superdégommage (voir brevets allemands n° 2609705 et 132877) comprenant aussi un cycle de refroidissement particulier, conduit à des teneurs en phosphore beaucoup plus faibles qu'avec un dégommage acide classique. Toutefois, le résultat final dépend fortement de la qualité de l'huile brute. Enfin, l'élimination du fer nécessite encore beaucoup de terre de blanchiment. Ce superdégommage a donc été complété (brevet européen n° 0 348 004) par un second cycle de refroidissement et l'addition d'eau ou de soude caustique pour améliorer l'épuration. Il en découle cependant un procédé très long, très complexe et coûteux.
• Un raffinage acide qui grâce à un acide dissocie les complexes phospholipidiques et ensuite les transforme en présence de soude caustique en complexe sodique parfaitement hydratable (voir les brevets américain n° 4.698.185 et européen n° 0 349 178 ainsi que la demande européenne n° 92200543.4). Ce procédé nécessitant une agitation intense permet d'obtenir des huiles à faible teneur en fer et en phospholipides; toutefois il requiert 2 à 3 séparations par centrifugation.

The total phospholipid content of these crude oils, expressed in the form of phosphorus, can be easily lowered from 800 ppm to 150-200 ppm by an aqueous degumming or delecithination. The oil is stirred in the presence of water at 80 ° C, causing hydration and flocculation of phospholipids. They can therefore be separated by decantation or centrifugation. The 150-200 ppm of phosphorus remaining, mainly represent non-hydratable phospholipids, which are complexes of phosphatidic acid and phosphatidyl ethanolamine associated with bivalent ions (such as calcium, iron, magnesium). The elimination of these non-hydratable phospholipids, made necessary for physical refining, can be carried out by means of a special degumming in different ways:

• An acid degumming which consists in dissociating the phospholipid complex using an acid and then hydrating it. This super degumming (see German patents no. 2609705 and 132877) also comprising a particular cooling cycle, leads to much lower phosphorus contents than with a conventional acid degumming. However, the end result is highly dependent on the quality of the crude oil. Finally, removing iron still requires a lot of bleaching earth. This super degumming was therefore completed (European patent n ° 0 348 004) by a second cooling cycle and the addition of water or caustic soda to improve the purification. However, this results in a very long, very complex and expensive process.
• An acid refining which, thanks to an acid, dissociates the phospholipid complexes and then transforms them in the presence of caustic soda into a perfectly hydratable sodium complex (see American patents n ° 4,698,185 and European n ° 0 349 178 as well as European application n ° 92200543.4). This process, which requires intense agitation, makes it possible to obtain oils with a low iron and phospholipid content; however it requires 2 to 3 separations by centrifugation.

We also know refining processes oils and fats by body treatment fatty first by an acid of the phosphoric acid type and then with a fatty acid salt or sodium carboxylate or potassium but these processes involve two stages of treatment of the fatty substance and do not allow to obtain a fine emulsion.

Documents FR-A-1 388 567, RESEARCH DISCLOSURE March 1981, No. 203, Havant Hampshire, GB 20306: Removal of non-hydratable phosphatides (NHP) from vegetable oils and DATABASE WPI, Week 8246, Derwent Publications Ltd., London, GB AN82-99201 describe oil refining processes.

One of the essential purposes of this invention consists in remedying the aforementioned drawbacks existing processes, and to provide a process industrially and economically valid to obtain fatty substances such as oils or fats, animal or vegetable, raw or delecithinated, perfectly degummed to allow their physical refining, allowing including virtually completely eliminating phospholipids which they contain, and more particularly non-hydratable phospholipids, when contain, and reduce their iron content.

To this end, the degumming process of the invention consists in mixing the fatty substance to be treated with a reactive aqueous solution of a complexing agent chosen from the group comprising citric acid, phosphoric acid, oxalic acid, tartaric acid, acids of the aminocarboxylic type, acids of polyhydroxycarboxylic type, polycarboxylic acids, the salts of these acids and mixtures of two or several of these substances and an emulsifier of the type anionic, cationic, zwitterionic, nonionic or generated in situ by partial neutralization of acids free fats present in the fatty substance, said solution allowing to extract the phospholipids contained in said fatty substance, said mixing being carried out by adding at once the aqueous solution of complexing agent and a fat emulsifier or vice versa and subjecting everything to intense agitation whose speed is between 500 and 15,000 rpm so as to form a fine emulsion.

According to a particular embodiment of the process of the invention, the stirring speed the above is between 1200 and 10,000 rpm.

According to a particular embodiment of the process of the invention, the above mixture is a temperature of 20 to 100 ° C, advantageously from 60 to 90 ° C.

According to a particularly embodiment advantageous of the invention, the complexing agent is trisodium citrate or is an acid of the aminocarboxylic type, such as ethylenediaminetetraacetic acid or the disodium or trisodium salt of the latter and the emulsifier is of the anionic type and is constituted by sodium lauryl sulfate, of the nonionic type and is consisting of one or more monoglycerides or is generated in situ and is sodium and / or potassium carboxylate.

According to another embodiment of the invention, the degumming process consists in dispersing the fatty substance in the form of fine droplets in a reactive aqueous solution of a complexing agent chosen from the group comprising citric acid, phosphoric acid, oxalic acid, tartaric acid, acids of the aminocarboxylic type, acids of polyhydroxycarboxylic type, polycarboxylic acids, the salts of these acids and mixtures of two or several of these substances and an emulsifier of the type anionic, cationic, zwitterionic, nonionic, or generated in situ by partial neutralization of acids free fats present in the fatty substance, said solution allowing to extract the phospholipids contained in said fatty substance.

The subject of the invention is also the degummed oils and fats, obtained according to process described above.

Other details and peculiarities of the invention will emerge from the description given below as a non-limiting example of some forms particular features of the invention.

As already specified above, the present invention proposes to erase fatty substances, such as oils or fats, animal or vegetable, crude or delecithinates, by bringing the fatty substance to be treated into contact with a reactive aqueous solution of a complexing agent and an emulsifier making it possible to hydrate not only the hydratable phospholipids but above all and in particular the non-hydratable phospholipids, if the latter contains them. As already mentioned above, the dissociation and hydration of non-hydratable phospholipids, such as phosphatidic acid and phosphatidyl ethanolamine associated with bivalent and trivalent metals (Ca ⁺⁺ , Mg ⁺⁺ , Fe ^{+ +} or Fe ⁺⁺⁺ ) is a difficult reaction. On the other hand, phosphatidic acid and phosphatidyl ethanolamine associated with monovalent metals (Na ⁺ , K ⁺ ) or even an H ⁺ cation, are easily hydrated and eliminated from the fatty substance. Until now, complex ionization reactions, in the presence of an acid, followed by an equilibrium shift in the presence of sodium hydroxide, made it possible to achieve this objective, but nevertheless required several separations by centrifugation for the removal of non-phospholipids. hydratable. According to the invention, the oil or fat to be degummed and the aqueous solution of complexing agent and emulsifier are mixed by adding the aqueous solution to the oil or fat at once or vice versa and subjecting the whole to intense agitation, the speed of which is between 500 and 15,000 revolutions / minute and advantageously between 1,200 and 10,000 revolutions / minute, for a duration generally of 10 seconds to 5 minutes. The purpose of this intense mixture is in fact to disperse the aqueous phase containing the reactants brought into contact (complexing and emulsifying agent) intensively in the oil or the fat so as to form a fine emulsion. The mixture of fatty substances / aqueous solution of the reactants brought into contact is generally carried out at a temperature of the order of 20 to 100 ° C., but a temperature between 60 and 90 ° C. is advantageously used. The aqueous phase thus formed is added or not with a sodium chloride solution whose concentration varies between 0.1 and 10% and is then separated by decantation or centrifugation so as to obtain a degummed fatty substance essentially free of phospholipids. The degummed fatty substance is then either dried and then treated with bleaching earth or treated directly without drying. The total content of phospholipids, expressed in the form of phosphorus, after degumming is much less than 10 ppm. Furthermore, a content of less than 0.2 ppm of iron is obtained, a value required for good conservation of the oil (AJ Dijkstra, B. Cleenewerk FST 317-322, 1992). The physical refining of the fatty substance, which takes place after degumming, therefore requires only a small quantity of bleaching earth, of the same order as that used for chemical refining.

According to the invention, the complexing agents have a much higher affinity constant for the bivalent cations than for the monovalent cations; therefore, they preferentially displace and complex the cations Ca ⁺⁺ , Mg ⁺⁺ , Fe ⁺⁺ , Fe ⁺⁺⁺ . The phosphatidic acid and the phosphatidyl ethanolamine thus released are therefore easily hydrated in sodium form. This complexation reaction of bivalent or trivalent cations (Mg, Ca, Fe) by the complexing agent requires the prior dissociation of the bivalent phospholipidecation complex. This requires both the presence of a complexing agent chosen from the group comprising citric acid, phosphoric acid, oxalic acid, tartaric acid, acids of the aminocarboxylic type, acids of the polyhydroxycarboxylic type. , polycarboxylic acids, the salts of these acids and mixtures of two or more of these substances and of an emulsifier of the anionic, cationic, zwitterionic, nonionic type or generated in situ by partial neutralization of the free fatty acids present in the body fatty and, as has just been specified, the use of intense stirring and a temperature preferably of at least 60 ° C., advantageously from 60 to 90 ° C. Examples of preferred complexing agents used in the context of the present invention are trisodium citrate or acids of the aminocarboxylic type, such as ethylenediaminetetraacetic acid or the disodium and trisodium salts thereof. The complexing agent will be used at least in stoichiometric amount relative to the amount of non-hydratable phospholipids or total cations (Mg, Ca, Fe) present in the fatty substance to be treated. The emulsifier, for its part, is of the anionic, cationic, zwitterionic or nonionic type. The anionic emulsifier, such as sodium lauryl sulfate, is particularly suitable. The emulsifier can also be generated in situ by partial neutralization of the free fatty acids present in the fatty substance. Emulsifiers produced in this way are, for example, sodium and potassium carboxylates. As non-ionic emulsifiers, non-limiting examples will be mentioned monoglycerides and their mixtures.

The amount of water in the solution mixture aqueous-fatty substance can vary between 0.1% and 99% in weight according to the separation conditions used. As previously stated, the reaction normally takes place between 10 seconds and 5 minutes but can be shortened or last longer if you modifies one of the parameters, for example the quantity of water used, reaction temperature, type of reagents brought together.

Degumming soybean oils as well than rapeseed, cotton, peanut, sunflower, corn has been successfully produced using the method of the invention. As already mentioned, the process of the invention is particularly suitable for degumming fatty substances containing phospholipids essentially formed of phospholipids not hydratable but also suitable for degumming fatty substances poor in non-hydratable phospholipids so as to better eliminate certain gums or mucilages. The degumming is carried out discontinuously or continuously, followed separation by decantation or centrifugation. A washing with water, after degumming the fatty substance, is beneficial but absolutely not necessary.

Fats, such as oil, can also be dispersed as fine droplets in an aqueous solution containing the chemical reagents. This technique described in the Belgian patent n ° 595.219, uses a column fitted with a dust jacket and a distribution system in which the body fat or oil is injected continuously in a form extremely divided. An infinite number is thus formed droplets of oil slowly rising against the current in the aqueous solution. These droplets of oil after coalescence at the top of the column are continuously separated by decantation or centrifugation. Generally, the reaction can be carried out in a counter-current extractor or in a column pulsed for liquid / liquid extraction. It is well understood that in the case of using this technique for dispersing the fatty substance in the form of fine droplets in the aqueous agent solution complexing and emulsifying, the dispersion will be also at a temperature between 20 and 100 ° C and advantageously between 60 and 90 ° C. As complexing agents and emulsifiers, we will use the same as those illustrated previously.

Examples of degumming are given below of fat produced on the basis of the process according to the invention.

EXAMPLE 1

7 g delecithinated soybean oil including phospholipid content, expressed as phosphorus is 80 ppm, and whose acidity expressed as acid oleic is 0.32%, are heated to 75 ° C in a beak. 21 ml of an aqueous solution composed of salt di- or trisodium ethylenediaminetetraacetate 5 millimolar and sodium lauryl sulfate 1.7 millimolar are also heated to 75 ° C. The solution water is added all at once to the oil. The mixture is agitated intensely for 45 seconds using a Ultra-Turax (type 725 = Janke & Kunkel KG) at 9.500 revolutions / minute.

The emulsion thus obtained is broken up by addition of 10 ml of a saturated chloride solution sodium or centrifuged directly at 5,000 rpm.

The phosphorus content determined by the calorimetric phosphorus determination method (AOCS ca 12-55) is 6 ppm. The cation content determined by atomic absorption according to the IUPAC 2.631 method is given in ppm. CATION BEFORE TREATMENT AFTER TREATMENT Magnesium 18 0.2 Calcium 46 1 Iron 0.55 0.04

By treating 7 g of delecithinated rapeseed oil in the same way as above, we obtain a phosphorus content determined by the same method of dosage of 5 ppm.

EXAMPLE 2

300 g of delecithinated soybean oil are heated to 75 ° C in a beaker. 900 ml of a solution aqueous compound of ethylenediaminetetraacetate salt di- or trisodium 5 millimolar and lauryl sulfate 1.7 millimolar sodium are also heated to 75 ° C. The aqueous solution is added all at once to the oil. The mixture is stirred intensely for 45 seconds at using an Ultra-Turax (type T45 = Janke & Kunkel KG) at 10,000 rpm.

The emulsion thus obtained is broken up by addition of 400 ml of a saturated chloride solution sodium or centrifuged directly at 5,000 rpm.

The phosphorus content determined by the colorimetric phosphorus determination method (AOCS ca 12-55) is 6 ppm. The determined cation content by atomic absorption according to the IUPAC method 2.631 is given in ppm.

The following results are given for two different soybean oils. SOYBEAN OIL N ° 1 BEFORE TREATMENT AFTER TREATMENT Phosphorus (ppm) 73 5.5 Acidity (oleic acid)% 0.32 Calcium 46 1 Magnesium 16 <0.2 Iron 0.55 0.04 SOYBEAN OIL N ° 2 BEFORE TREATMENT AFTER TREATMENT Phosphorus (ppm) 122 6.5 Acidity (oleic acid)% 4.24 Calcium 68 1 Magnesium 36 <0.2 Iron 4.9 0.05

EXAMPLE 3

300 g of delecithinated soybean oil, the phospholipid content, expressed as phosphorus is 80 ppm, and whose acidity expressed as acid oleic is 0.32%, are heated to 75 ° C in a beak. 900 ml of an aqueous solution composed of 10 millimolar trisodium citrate and lauryl sulfate of 1.7 millimolar sodium are also heated to 75 ° C. The aqueous solution is added all at once to oil. The mixture is stirred intensely for 45 seconds using an Ultra-Turax (type T 45 = Janke & Kunkel KG) at 10,000 rpm.

The emulsion thus obtained is broken up by addition of 10 ml of a saturated chloride solution sodium or centrifuged directly at 5,000 rpm.

The phosphorus content determined by the colorimetric phosphorus determination method (AOCS ca 12-55) and the cation content determined by atomic absorption according to the IUPAC 2.631 method is given below. BEFORE TREATMENT AFTER TREATMENT Phosphorus 80 2.2 Iron 0.55 0.03

EXAMPLE 4

According to the conditions described in the Example 1, the test was carried out in the presence of different emulsifiers with a concentration of 1.7 millimolar remains constant.

The table below gives the phosphorus content after treatment with two different soybean oils. SOYBEAN OIL N ° 1 SOYBEAN OIL N ° 2 Acidity% 0.32 4.24 (ac.oleic)% Phosphorus ppm 73 122 EMULSIFIERS RESIDUAL PHOSPHORUS AFTER TREATMENT RESIDUAL PHOSPHORUS AFTER TREATMENT ANIONIC Dioctylsultosuccinate 5.2 7.1 Na lauryl sulfate 6.1 7.3 CATIONIC Cetylpyridinium 4.0 6.3 Dodecyltrimethylammonium 5.5 5.2 Hexadecyltrimethylammonium 4.5 7.4 Tetradecyltrimethylammonium 4.9 5.1 ZWITTERIONICS Lauryl sulfobetaine 4.7 7.3 Tetramethylsulfobetaine 5.8 6.6 NON IONIC Triton X100 3.1 3.3 Triton X114 2.3 3.1 Tween 20 3.5 3.4

Claims (15)

1. Method of degumming a fatty substance such as an animal or vegetable oil or fat, either unrefined or from which the lecithin has been removed, whereby this fatty substance is mixed with a reactive aqueous solution of a complexing agent and an anionic, cationic, zwitterionic or non-ionic emulsifier, or one produced in situ by partially neutralising the free fatty acids present in the fatty substance, said solution making it possible to extract the phospholipids contained in said fatty substance, and said mixture being realised by adding the aqueous solution of complexing agent and emulsifier to the fatty substance, or vice versa, in a single operation, characterised in that the entire mixture is subjected to intense agitation at a speed of between 500 and 15,000 r.p.m. so as to form a fine emulsion, the complexing agent being selected from the group comprising citric acid, phosphoric acid, oxalic acid, tartaric acid, aminocarboxylic acids, polyhydroxy carboxylic acids, polycarboxylic acids, the salts of these acids and mixtures of two or more of these substances.
2. Method according to claim 1, characterised in that the speed of agitation is 1,200 to 10,000 r.p.m.
3. Method according to either of claims 1 and 2, characterised in that the mixing operation is carried out at a temperature of 20 to 100 °C.
4. Method according to claim 3, characterised in that a temperature of between 60 and 90 °C is employed.
5. Method according to any of claims 1 to 4, characterised in that after the aforesaid mixing operation the aqueous phase thereby formed is separated so as to obtain a degummed fatty body substantially free of phospholipids.
6. Method according to any of claims 1 to 5, characterised in that the aforementioned mixing is carried out prior to the operation of physically refining the fatty substance.
7. Method according to claim 1 for degumming a fatty substance such as an animal or vegetable oil or fat, either unrefined or from which the lecithin has been removed, whereby this fatty substance is mixed with a reactive aqueous solution of a complexing agent and an anionic, cationic, zwitterionic or non-ionic emulsifier, or one produced in situ by partially neutralising the free fatty acids present in the fatty substance, said solution making it possible to extract the phospholipids contained in said fatty substance, characterised in that the fatty substance is dispersed in the form of fine droplets in the aforementioned reactive aqueous solution, the complexing agent being selected from the group comprising citric acid, phosphoric acid, oxalic acid, tartaric acid, aminocarboxylic acids, polyhydroxy carboxylic acids, polycarboxylic acids, the salts of these acids and mixtures of two or more of these substances.
8. Method according to claim 7, characterised in that dispersion is carried out at a temperature of 20 to 100 °C.
9. Method according to claim 8, characterised in that a temperature of between 60 and 90 °C is employed.
10. Method according to any of claims 1 to 9, characterised in that the phospholipids contained in the fatty substances are substantially formed by non-hydratable phospholipids.
11. Method according to any of claims 1 to 10, characterised in that the complexing agent is trisodium citrate or of the aminocarboxylic type, such as ethylene diamine tetraacetic acid or the disodium or trisodium salt thereof.
12. Method according to any of claims 1 to 11, characterised in that the complexing agent is utilised in at least a stoichiometric quantity in relation to the quantity of non-hydratable phospholipids present in the fatty substance.
13. Method according to any of claims 1 to 12, characterised in that the emulsifier is of the anionic type and is sodium lauryl sulphate.
14. Method according to any of claims 1 to 12, characterized in that the emulsifier is produced in situ and is sodium and/or potassium carboxylate.
15. Method according to any of claims 1 to 12, characterised in that the emulsifier is non-ionic and is constituted by one or more monoglycerides.