EP0070269A2 - Process for treating oils and fats and products so obtained - Google Patents

Abstract

Process for treating a crude, half-processed or refined, animal or vegetable oil or fat, which consists in adding to it at least one enzyme enabling the nonglyceride components present therein to be hydrolysed and/or depolymerised.

Description

The present invention relates to a process for the biological treatment of crude, semi-treated or refined oils and fats, animal or vegetable, as well as to the oils and fats thus obtained.

It is well known that almost all oils and fats, in solution or in suspension, contain non-lipids and phosphatides. For simplicity, the terms "non-lipids" and "phosphatides" will be repeated below under the more general term "non-glycerides", following the classification of the "Bailey's Industrial Oil & Fat _P roducts" 4th edition, 1980, Volume 1, pages 45 to 83, edited by Daniel SWERN, Wiley Interscience Publication, New York USA. These can be present in appreciable quantities, such as, for example, in shea butter, illipe oil, certain marine oils such as sperm whale spermaceti, certain crude animal oils and fats such as dehydrated butter, fat chicken, etc; but often these non-glycerides are in the state of low concentration, even traces, but nevertheless having a marked inhibitory effect on the treatments (for example a negative effect on the crystallization) or annoying for finished products (for example, a negative effect on the thinning of oils), as may be the case for sunflower, cotton, olive-pomace oils, etc.

It is well known that the "impurities" of the treated oils have a harmful effect on the operations and the yields of the refining, which is why the neutralization or deacidification of the oils is generally preceded by a prior "degumming". Similarly, in fractionation by crystallization, the presence of non-glycerides, can have, even in trace amounts, a marked inhibitory effect on the crystallization of oils and fats.

Among these non-glyceridic and often inhibitory substances contained in oils and fats, especially in crude oils, there is first of all the phosphatides. Phosphatides, the most common of which are lecithins and cephalins, are triglycerides in which one of the acyl radicals (-CO-R) is substituted by phosphoric acid, itself being saturated with a basic group, for example choline or cholamine. Phosphatides have a notable emulsifying and anti-crystallizing power.

• - les hydrates de carbone ou glucides, rangés en deux groupes principaux, les monosaccharides et les polysaccharides. Les monosaccharides, tels que le glucose, le galactose, etc., existent généralement dans les huiles et graisses sous forme de complexes sucres-phospholipides (par exemple l'inositol qui est une combinaison de phosphatide et de galactose, ou encore la phytostéroline, composée de phytostérol et de glucose). Les polysaccharides, principalement les polyholosides (gommes, cellulose, .....) qui, en tant que hauts polymères, sont insolubles dans l'eau ou fournissent des solutions colloïdales. Ces polysaccharides peuvent s'hydrolyser jusqu'à la dégradation complète en monosaccharides. Certains sont solubles dans l'eau à chaud (glycogène, amidon, pectine) mais peuvent former des masses gélatineuses;
• - certaines protéines simples (gélatine) et composées (caséine) ainsi que certains produits de dégradation (peptones, protéoses) qui peuvent se trouver solubilisés dans les huiles et graisses, en particulier si les graines et fruits oléagineux ou les tissus animaux dont ils sont issus ont été endommagés par une décomposition hydrolytique antérieure à leur extraction;
• - certaines résines, cires, latex et mucilages divers; les stérols en tout genre;
• - les pigments caroténoïdes, etc.

Among the non-lipids contained in oils and fats, we can note:

• - carbohydrates or carbohydrates, classified into two main groups, monosaccharides and polysaccharides. Monosaccharides, such as glucose, galactose, etc., generally exist in oils and fats in the form of sugar-phospholipid complexes (for example inositol which is a combination of phosphatide and galactose, or phytosteroline, composed of phytosterol and glucose). Polysaccharides, mainly polyholosides (gums, cellulose, .....) which, as high polymers, are insoluble in water or provide colloidal solutions. These polysaccharides can hydrolyze until complete degradation into monosaccharides. Some are soluble in hot water (glycogen, starch, pectin) but can form gelatinous masses;
• - certain simple proteins (gelatin) and compounds (casein) as well as certain degradation products (peptones, proteoses) which can be dissolved in oils and fats, in particular if the oil seeds and oleaginous fruits or the animal tissues from which they come have been damaged by hydrolytic decomposition prior to their extraction;
• - certain resins, waxes, latex and various mucilages; sterols of all kinds;
• - carotenoid pigments, etc.

Although most of the phosphides and non-lipids in general, found in oils and fats, are eliminated during neutralization with alkalis, these foreign substances. oil or fat itself interfere with the effectiveness of treatments, especially during centrifugation, filtration, crystallization, fractionation, sintering and clearing.

One of the essential aims of the present invention consists in remedying the abovementioned drawbacks of existing oils and greases, and in providing for an industrially and economically valid process making it possible to obtain oils and greases which are clearly "cleaner" and of a lower viscosity than oils or fats treated according to conventional methods, in particular during the various abovementioned operations to which the oils or fats are subjected.

To this end, the method according to the invention consists in adding to the oil or fat to be treated, at least one enzyme making it possible to hydrolyze and / or depolymerize the non-glyceridic components contained therein.

According to a particular embodiment of the process of the invention, the enzyme is added before the operations of centrifugation, filtration, crystallization, fractionation, wintering or clearing of this oil or fat.

According to a particularly preferred embodiment of the invention, the enzyme is chosen from the group comprising phosphatases, pectinases, cellulases, amylases, gumases, proteases and mixtures of two or more of these substances.

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

Other details and particularities of the invention will emerge from the description given below by way of nonlimiting example of some particular forms of the invention.

As already follows from the above, the present invention proposes to pre-treat oils and fats, by means of suitable enzymes, so as to greatly improve the operating conditions such as centrifugation, filtration, crystallization, fractionation, sintering or thinning. Thus, if the conditions of crystallization of an oil or grease are greatly improved, the conditions of filtration are automatically improved, or else this filtration is simply made possible. Likewise, if good crystallization is essential, during wintering and fractionation operations, it essentially depends on the "cleanliness" of the oil treated. Fractionation is the progressive cooling (refrigeration) of a fat, followed by a separation of the crystals, in order to obtain two different fatty phases. Winterization is the freezing of a liquid oil, followed by a separation of the crystals, with the aim of obtaining, by filtration or centrifugation, a clear main phase. Among the industrial processes of winterization and fractionation, may be mentioned, for example, crystallization and filtration processes described in Belgian Patents No. 713,430 and No. _'713 330. The clearing is an operation of polishing the oils, retaining the troubles, impurities and mini-crystals present in the oils, on filtering surfaces, so as to make them clear and shiny.

Enzymes are effect proteins powerful and very selective catalytic. In fact, each enzyme has the property of specifically catalyzing an organic reaction via the formation of an enzyme-substrate complex. It has thus been found, according to the invention, that a certain number of enzymes specifically attack the non-glyceridic components of various oils and fats, due to the very nature of this component.

Among the enzymes specifically active in this field, mention will be made, in particular, of phosphatases (phospholipases-C), which attack phosphatides: pectinases, cellulases, amylases, specific to the various carbohydrates; gumases, specific to vegetable gums and mucilage; proteases which hydrolyze proteins (gelatins and caseins). Triglyceridases like lipases of the pancreatic type, which attack glycerides themselves by hydrolyzing fat, are not part of the field of enzymes useful for the treatment of non-glyceridic components.

Given the complexity of the non-glyceridic residues of certain oils and fats and the specificity of the proper action of enzymes, it may be necessary to use several enzymes together. Moreover, it often happens that the commercial "enzymes", whether of animal, vegetable or microbiological origin, actually contain several enzymes with different specific actions. Thus, for example, papain and ficin, products extracted from the fruit of the papaya tree and the fig tree, contain both proteases and phosphatases and peroxidases. Similarly, care should be taken to avoid using enzyme complexes for oils and fats, some of which could have negative effects, for example, by producing oxidations or hydrolyses in the oil or fat itself.

• 1°) L'addition et le mélange dans les huiles et les graisses, d'enzyme ou de complexes d'enzymes préalablement dissous dans une faible quantité de solvant approprié (par exemple de l'eau). Un certain nombre de solvants sont possibles mais on choisira un solvant non toxique et convenant à l'enzyme. Cette addition peut se faire aussi bien dans les traitements par charges successives que dans les traitements continus. La quantité nécessaire d'enzyme (s) à ajouter aux huiles et graisses, selon ce procédé, peut aller, suivant les enzymes et les produits à traiter, de 2₀ à 400 ppm, c'est-à-dire de 0,02 kg à 0,4kg d'enzyme pour 1000 kg d'huile ou de graisse, et de préférence de 20 à 100 ppm, c'est-à-dire de ₀,₀2 à O,1 kg d'enzyme pour 1000 kg d'huile, ces valeurs s'entendant en enzymes concentrées, c'est-à-dire sans diluant ou solvant.
• _2°) Le passage de l'huile ou de la graisse à travers un lit filtrant d' enzyme (s) fixée (s) ou "insolubilisée(s)" sur des supports solides ou semi- solides, présentant de préférence une structure poreuse ou fibreuse. Dans cette technique, les enzymes sont emprisonnées dans les micro-cavités de la structure poreuse ou fibreuse des supports. Ceux-ci seront constitués, par exemple, par des résines ou des polymères synthétiques, des carbonates de cellu- ,.lose, des gels tels que l'agarose, des filaments de polymères ou de copolymères à structure poreuse, emprisonnant dans leurs cavités de fines gouttelettes d'enzyme en solution. Pour ce qui est de la concentration en enzyme, on peut aller jusqu'à la saturation des supports.
• 3°) La dispersion des huiles et des graisses sous forme de fines gouttelettes, dans une solution enzymatique diluée, contenant de préférence de 0,2 à 4% en volume d'enzyme. Cette technique est décrite notamment dans le brevet belge n° 595.219. Une colonne cylindrique de plusieurs mètres de haut à couvercle conique, est remplie d'une solution enzymatique diluée. On choisira, à cet effet, un solvant non toxique et non miscible dans l'huile ou la graisse à traiter, de préférence de l'eau. Le fond de la colonne est équipé d'un système de distribution dans lequel l'huile ou la graisse est injectée en continu sous une forme extrêmement divisée environ 10.000 flux par m²). Il se forme ainsi un nombre infini de gouttelettes d'huile ou de graisse, qui montent lentement dans la solution d'enzymes et se réunissent à la surface, pour s'évacuer en continu au sommet du couvercle conique du réacteur.

According to the invention, the techniques for treating oils and fats which can carry out, by the enzymatic route, the hydrolysis and / or depolymerization of the non-glyceridic components which they contain, are of three types:

• 1) Addition and mixing in oils and fats, of enzyme or enzyme complexes previously dissolved in a small quantity of suitable solvent (for example water). A number of solvents are possible but a non-toxic solvent suitable for the enzyme will be chosen. This addition can be done both in the treatments by successive loads as in the continuous treatments. The necessary quantity of enzyme (s) to be added to oils and fats, according to this process, can range, depending on the enzymes and the products to be treated, from ₂₀ to 400 ppm, that is to say from 0.02 kg to 0.4 kg of enzyme per 1000 kg of oil or fat, and preferably from 20 to 100 ppm, i.e. from _{0.02 to 0.1} kg of enzyme per 1000 kg of oil, these values being understood as concentrated enzymes, that is to say without diluent or solvent.
• _{2 °} ) The passage of oil or fat through a filtering bed of fixed enzyme (s) or "insolubilized (s)" on solid or semi-solid supports, preferably having a porous or fibrous structure. In this technique, the enzymes are trapped in the micro-cavities of the porous or fibrous structure of the supports. These will consist, for example, of resins or synthetic polymers, carbonates of cellu-, .lose, gels such as agarose, filaments of polymers or copolymers with porous structure, trapping in their cavities. fine droplets of enzyme in solution. In terms of enzyme concentration, we can go as far as the saturation of the supports.
• 3 °) The dispersion of oils and fats in the form of fine droplets, in a dilute enzymatic solution, preferably containing from 0.2 to 4% by volume of enzyme. This technique is described in particular in Belgian patent n ° 595.219. A cylindrical column several meters high with a conical cover is filled with a dilute enzymatic solution. A non-toxic and immiscible solvent in the oil or fat to be treated, preferably water, will be chosen for this purpose. The bottom of the column is equipped with a distribution system into which the oil or fat is injected continuously in an extremely divided form (approximately 10,000 flows per m ² ). This creates an infinite number of droplets of oil or fat, which rise slowly in the solution of enzymes and meet on the surface, to be continuously discharged at the top of the conical cover of the reactor.

In all these techniques, it is important to respect the concentration, temperature and pH conditions which allow the enzyme to give its maximum catalytic effect. To this end, according to the invention, the enzymatic reaction will be carried out at a temperature between 10 ° and 90 ° C, and preferably at a temperature between 25 ° and 55 ° C, and at a pH of the order of 1 to 7. This is particularly important for concrete fats, for which enzymes stable at the temperature where the fat is perfectly melted will be chosen. In general, the enzymatic reaction is allowed to continue for a period of time allowing the practically total hydrolysis and / or depolymerization of the non-glyceridic components which contain the oil or the fat. At the end of the operation, or during a subsequent step, the enzymatic effect is necessarily stopped by the addition of an inhibitor or simply by the heat, for example by heating to a temperature of at least 85 ° C., in the extent to which the enzymatic reaction could continue undesired (for example with an oxidizing or hydrolyzing effect on the oils and fats themselves).

According to the invention, a typical example of the application of the process for the treatment of non-glyceridic components of oils and fats by the addition of enzymes is the treatment with pectinase. crude palm oil, to allow crystallization and fractionation thereof without subjecting it to current refining operations.

For the past dozen years, fractionation by crisallization of palm oil has taken a very important place in the treatment of this oil. More than a quarter of the palm oil produced in the world - estimated at 4,682 thousand tonnes for 1980-81 - J.A.O.C.S. January 1981) is marketed in the form of its liquid and concrete fractions. In Malaysia, more than 30 industrial units practice the fractionation of palm oil. In Indonesia, 3 factories are sufficient to fractionate half of the country's palm oil production. But all of these palm oil fractionation workshops are located in oil refineries, as one of the stages in refining operations. There are currently none installed in the oil mills of plantations producing crude palm oil. The reason is that, while the crystallization of a refined oil is relatively easy, it is extremely unsatisfactory, and often impossible, in the case of a crude palm oil.

This is because, in addition to free fatty acids, crude palm oil contains phosphatides and non-lipid components, generally referred to as "mucilages" or "gums", which, although apparently unimportant ( 0.2 to crude oil), have a detrimental damaging effect on shouting tallization of crude oil. This is why, before any other operation, the crude palm oil is generally subjected to a prior "degumming". This degumming generally consists of an attack of the crude oil with a concentrated solution of phosphoric acid (0.05 to 0.2% by volume), which more or less attacks the gums by precipitating them so as to retain them during subsequent filtration on active soils.

But degumming crude palm oil with phosphoric acid has many drawbacks. Unless careful, concentrated phosphoric acid (85%) also attacks the oil itself, causing partial degradation of the oil by formation of phosphate residues- In addition, the precipitates formed in the oil must necessarily, before any other operation, be filtered and retained by a sufficient quantity of active earths, Hence a new loss of oil, the earths retaining oil up to the amount of some 40% of their own weight. The palm oils thus treated on the land undergo significant discoloration which prevents them from being considered as crude oils, which often has a significant effect on the customs duties of importing countries (in 1981, the difference in duties in the EEC was 10% of the value of imported palm oil). Finally, phosphoric acid imparts to the treated oil an extremely troublesome, or even inhibiting, mineral acidity for the crystallization itself. This is the reason why certain processes "neutralize" the traces of unreacted phosphoric acid in the oil, by for example, by alkali hydroxides or calcium carbonate. However, this neutralization has the disadvantage of giving rise to soaps, sodium or calcium, which are powerful inhibitors of crystallization. It is therefore necessary to retain these soaps in turn on active soils, with the disadvantages exposed above.

The treatment of crude palm oil with enzymes avoids the drawbacks mentioned above. The enzymes have an absolutely specific action on the oil: the pectinases, for example, will selectively hydrolyze the pectins, which are numerous in crude palm oil, especially since the introduction into the oil mills of high-performance continuous presses, extracting with l oil part of the components of vegetable fibers. Enzymes have the enormous advantage of acting on oils, which are delicate biological compounds, without violent acidification and at exceptionally moderate temperatures, the enzymes having their activity at temperatures very close to ambient temperatures. The enzymes leave the crude palm oils with all their crude oil characteristics and make it possible to fractionate them, without loss of material, at the oil mill level, without all the equipment which is expensive in terms of investment and production costs. of the oil refinery.

To illustrate the invention more concretely, two examples of treatment, one carried out with phosphoric acid (comparative example 1) and the other according to the invention (example 1) on an oil commercial raw palm, having 4.94% of free fatty acids and an iodine value of 52.98, are given below.

Comparative example 1.

Initially, this palm oil was subjected to 14 successive fractionation tests, either as it was or after various treatments, such as centrifugation, washing, attack with phosphoric acid and partial discoloration with active earth (2 % of Tonsil FF optimum), but always avoiding neutralization of the oil. All these tests were negative, the crystals formed being extremely small (0.02 to 0.15 mm in diameter), shapeless and without consistency, in a very viscous liquid suspension.

Example 1.

According to the invention, the following test is carried out:

A - Enzvmage:

A load of 30 kg of crude palm oil is heated to + 50 ° C. 1% solutions in distilled water of Celluclast 2.OL typex (cellulase) and Ultrazym 100 (pectinase) enzymes are prepared and 600 g of each of these aqueous solutions are added to the oil, with vigorous stirring for a few minutes. The oil is then kept at + 50 ° C., with moderate stirring, for a total reaction time of two hours. Then the temperature is raised to ⁺ 90 ° C to deactivate the enzymes and prepare the mixture for filtration. The oil is dried under vacuum and filtered with a filter aid (Celatom). B - Splitting:

The enzymatic crude palm oil is subjected to normal crystallization, by heating to 68 ° C. followed by controlled cooling. Excellent crystallization is obtained, most of which have very firm and rounded crystals of 0.5 to 0.9 mm in diameter, with a few medium or small crystals. Then filtered on a vacuum filter, the oil thus crystallized filtered in 16 to 22 seconds, leaving a very dry stearin cake 12 mm thick and a very liquid and shiny olein. The crystallization tests were repeated several times, with the same success.

For this purpose, we will compare the attached Figures 1 and 2, which respectively represent the photographs taken under stereoscope, in polarizing light, respectively of the crystals obtained according to Comparative Example 1 (magnification 30 x) and of the crystals obtained according to the example 1 of the invention (magnification 20 x).

It is understood that the invention is in no way limited to the embodiments described and that many modifications can be envisaged without departing from the scope of this patent.

In fact, given the large number of oils and fats containing non-glyceridic components which can usefully be hydrolyzed or depolymerized to improve their performance during treatments by centrifugation, filtration, cris. tallization, fractionation, winterization and clearing, and also considering the large number of enzymes including the specific action may be useful for the same purpose, it is obvious that the examples could be considerably increased, each of the oils and fats and each of the enzymes being a case in point. Thus, oils and fats, such as chicken fat, shea butter, illipe butter, salfat and cottonseed oil, could also be treated by the process of the invention.

Claims (14)

1. Process for treating a crude, semi-processed or refined oil or fat, animal or vegetable, characterized in that it consists in adding to this oil or fat, at least one enzyme making it possible to hydrolyze and / or depolymerize the non-glyceridic components contained therein. 2. Method according to claim 1, characterized in that the enzyme is added before the operations of centrifugation, filtration, crystallization, fractionation, wintering or clearing of this oil or fat. 3. Method according to either of Claims 1 and 2, characterized in that the enzyme is chosen from the group comprising phosphatases, pectinases, cellulases, amylases, gumases, proteases and mixtures of two or more of these substances. 4. Method according to any one of claims 1 to 3, characterized in that the above-mentioned treatment is carried out by adding the enzyme in the dissolved state in the form of a solution in a non-toxic solvent, under conditions of intense agitation. 5. Method according to claim 4, characterized in that the quantity by weight of enzyme per 1000 kg of oil or fat is between 0.02 and 0.4 kg. 6. Method according to claim 5, characterized in that the amount by weight of enzyme per 1000 kg of oil or fat is between 0.02 and 0.1 kg. 7. Method according to any one of claims 1 to 3, characterized in that the above treatment is carried out by passing the oil or the fat over an enzyme filter bed fixed on a solid or semi-support. solid. 8. Method according to claim 7, characterized in that the support has a porous or fibrous structure. 9. Method according to any one of claims 1 to 3, characterized in that the above-mentioned treatment is carried out by dispersing the oil or the fat in the form of fine droplets, in a dilute enzymatic solution, the solvent used for this purpose being non-toxic and immiscible in this oil or fat. 10. Method according to claim 9, characterized in that the enzymatic solution contains 0.2 to 4% by volume of enzyme. 11. Method according to any one of claims 1 to 10, characterized in that the enzymatic reaction is allowed to continue for a period of time making it possible to obtain the practically total hydrolysis _{and / or d} epolymerization of the non-glyceridic components. . 12. Method according to any one of claims 1 to 11, characterized in that the enzymatic reaction is carried out at a temperature between 1C ° and 90 ° C and at a pH of 1 to 7. 13. Method according to claim 12, characterized in that the enzymatic reaction is carried out at a temperature between 25 ° and 55 ° C. 14. Method according to any one of claims 11 to 13, characterized in that after the hydrolysis and / or the depolymerization practically total of the non-glyceridic components, .on the fat or the enzyme oil is heated to a temperature at least 85 ° C, an inhibitory substance is added thereto, so as to deactivate the enzyme or enzymes.

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