FR2702774A1 - Refining of vegetable or animal oils by filtration - Google Patents

Abstract

The subject of the present invention is a new process for refining vegetable or animal oils. The said process comprises: - the addition to the said oils of at least one surface-active agent and/or of at least one agent capable of generating a surface-active agent therein; - the filtration of the mixtures through a filter whose porosity is between 0.1 and 100 mu m and advantageously between 1 and 50 mu m; - the recovery of filtrates consisting of oils with a low phosphorus content and of retentates which are rich in phospholipids. Advantageously, the said oils are neutralised with a suitable base and, on the one hand, filtrates consisting of neutral oils with low phosphorus and free fatty acids contents are recovered and, on the other hand, retentates rich in phospholipids and in soaps are recovered.

Description

 Refining of vegetable or animal oils by filtration.

 The subject of the present invention is a new process for the refining of vegetable or animal oils with a view to eliminating impurities liable to alter the quality of these oils or hindering subsequent processing steps in said refining. Said oils can thus be refined for their use for food, cosmetic, pharmaceutical, energy or other purposes.

 Crude oils of animal or vegetable origin consist essentially of triglycerides. They also contain other constituents that must be removed during the refining process. It is mainly free fatty acids, phospholipids, glycolipids, metals, pigments, volatile substances affecting the smell and taste ...

 The traditional purification of crude oils, called refining is carried out in a series of steps each aimed at eliminating some of the constituents other than glycerides.

As an example, let us quote the traditional process of refining edible oils, such as soybean oil, which has four main stages:
- degumming or degumming which allows the elimination of phospholipids or phosphatides;
neutralization or deacidification (alkaline treatment) which makes it possible to eliminate free fatty acids in the form of soaps;
- discoloration or bleaching with bleaching earth and / or activated charcoal; and
- the deodorization which eliminates the volatile substances influencing the smell and the taste; operation carried out by steam distillation at a temperature of at least 180in and at a reduced pressure of less than or equal to 3 mm of mercury.

 This process is expensive because of the relatively high number of operations performed and the losses of neutral oil generated at each stage.

 In addition, the alkaline treatment poses the problem of the removal of soaps and the discoloration that of the evacuation of the used discoloration agent.

Some authors have written that in the apolar organic medium, phospholipids associate in micellar aggregates whose size is larger than
that of triglycerides. This property has led to the development of increasingly sophisticated refining techniques by ultrafiltration of oils and fats.

 EP-A-0 092 439 recalls in its introductory part the evolution of the technique in this respect.

 It also describes an improved process for the refining of oils or fats in which an oil containing free fatty acids, in solution in an apolar solvent is neutralized, preferably by the addition of a base, in particular of ammonia (or ammonia) for saponifying said free fatty acids, and the oil thus neutralized and optionally added phospholipids is fractionated by ultrafiltration into a permeate containing an oil of a suitable purity in the solvent and a retentate containing in particular the phospholipids.

 This process is particularly advantageous since it makes it possible to eliminate not only phospholipids and free fatty acids, thus simultaneously effecting degumming and deacidification of the crude oil, but also traces of metals and soaps, as well as part of the pigments.

 According to this process of the prior art, the ultrafiltration is carried out on a semi-permeable membrane whose cutoff threshold is generally between 10,000 and 300,000 daltons, preferably between 25,000 and 100,000 daltons, at a temperature of between 100C and 70iC and at a pressure between 2 and 50 bar.

 This process, as well as all of the refining processes using ultrafiltration, advocates the solution of the crude oils in an apolar solvent and the use of organic membranes.

 The use of these membranes is however delicate because of their fragility. In addition, the life of these membranes is limited, especially when in contact with relatively aggressive media (oils and solvents). Finally, the membranes used are generally provided in an aqueous medium that must be removed before use, which makes their implementation less easy.

 Moreover, the use of an apolar solvent, generally flammable, imposes severe safety conditions.

 The object of the present invention is to propose a novel process for refining vegetable or animal oils, which is simple to implement and inexpensive, and which makes it possible to obtain an oil of suitable purity.

 It has been discovered, and this constitutes the foundation of the present invention that it was possible to refine the vegetable or animal oils by simple filtration through a filter whose porosity is between 0.1 and 100, rem.

More specifically, the refining process according to the invention comprises the following three main stages:
the addition to the oils of at least one surfactant and / or at least one agent capable of generating, within said oils, a surfactant;
filtration of the mixture (oil + agent (s)) through a filter whose porosity is between 0.1 and 100 μm, advantageously between 1 and 50 μm; ;
- The recovery of filtrates consisting of low phosphorus oils and retentates rich in phospholipids.

 Advantageously recovered are filtrates consisting of low water content oils and phospholipids and retentates rich in phospholipids and other surfactants, including those resulting from the prior addition.

 The process of the invention is characterized in that the result expected for the elimination of phospholipids can be obtained by simple filtration as long as the addition to the oils of the appropriate agent (s) generates containing phospholipids larger than those of the pores of a conventional filter.

 In this, the method of the invention is particularly advantageous.

Those skilled in the art do not ignore, indeed, the multiple advantages of filtration compared to ultrafiltration. It will be noted here in particular that the filtration technology, commonly used in the food industry, is of an implementation incomparably simpler and therefore less expensive than that of ultrafiltration. So
- Filtration fluxes are commonly 10 to 100 times greater than those of ultrafiltration;
- at equal flow, the operating pressure for filtration is much lower than that which must be applied for ultrafiltration;
the filters used in filtration do not require prior treatments, unlike ultrafiltration membranes. They have a high load capacity, so a high durability before clogging.

 According to the invention, it has surprisingly been found that the intervention of surfactants or precursors of such agents in oils leads to the formation of bulky entities containing the phospholipids. To date, the exact physical nature of these entities is not known. However, those skilled in the art are able to experimentally determine the optimal amount of intervention of such agents.

 Said surfactants, when the oils are refined for food, cosmetic or pharmaceutical purposes, are chosen from those compatible with the laws on foodstuffs, cosmetics or pharmaceuticals.

 The intervention of agents not compatible with these legislations is not excluded insofar as the oils treated according to the invention can be used for purely industrial purposes. To be used for these purposes, for example as fuel or lubricant, they may undergo, after the refining of the invention, a physical and / or chemical treatment.

In particular, it is possible to use for the purposes of the invention:
nonionic surfactants such as sugar esters;
- Soaps as such or advantageously in the form of neutralization pastes. Said pastes are by-products of conventional crude oil refining processes;
partial glycerides (mono- or di-glycerides) derived from vegetable oils;
phospholipids (or lecithins) as such or advantageously in the form of a filtration retentate which is thus recycled.

 As specified above, therefore, an effective amount of such surfactants is added to the oils to be refined in order to filter out the phospholipids contained in said oils. Said surfactants can be generated in situ by addition of a precursor. Indeed, it is known that certain non-surfactant agents can form compounds with surface properties by association and / or complexation with endogenous molecular entities. By way of example, such non-surfactant agents may consist of starches, dextrins, crown structures such as cyclodextrins. Thus, according to a preferred variant of the process of the invention, a base or any other neutralizing agent is added to the oils.The base-precursor neutralizes the free fatty acids in said oils and generates soapsurfactants.

According to this preferred variant, the method of the invention comprises:
the neutralization of the oils with at least one appropriate base;
the filtration of said neutralized oils through a filter whose porosity is between 0.1 and 100 μm, advantageously between 1 and 50 μm;
the recovery of filtrates consisting of neutral oils with a low content of phosphorus and of free fatty acids and retentates rich in phospholipids and soaps.

 This variant of the process of the invention is particularly advantageous in that it makes it possible to simultaneously dispose of phospholipids and free fatty acids as well as other undesirable molecular species (pigments, oxidation products, metals and other compounds polar).

 Insofar as the process of the invention is limited to demucilagination or involves only partial neutralization, it will be necessary to add to its three main stages (addition of surfactants - filtrate recovery of the filtrate) an additional step of deacidification, if it is desired to eliminate all of the free fatty acids initially present in the oil.

 Incidentally, the degumming according to the invention also makes it possible to eliminate traces of metals, soaps, pigments and other polar compounds. Said impurities are trapped in the entities containing the phospholipids.

 According to the preferred variant of the process, said entities contain phospholipids and soaps.

 According to this variant, at least one suitable base has been added to the oils to be treated. This is advantageously chosen from aqueous solutions of sodium hydroxide, potassium hydroxide, ammonia, and mixtures thereof. Solids such as lime or magnesia can also be used. In order to eliminate all the free fatty acids, at least a stoichiometric amount of said base, preferably a slight excess thereof, will be involved with respect to said stoichiometric amount, in order to move the reaction in the right direction . Care should be taken not to introduce more water than necessary into the medium to be filtered.

The Applicant has shown that advantageously:
for the neutralization of the oils to be filtered according to the invention, the stoichiometric amount plus 10% in excess of a strong aqueous base solution in weight is added). Said strong base is advantageously sodium hydroxide;
for the neutralization of oils having an acidity of less than 1%, 30% by weight aqueous sodium hydroxide solutions are used and, for the neutralization of oils having an acidity greater than 1%, aqueous solutions of sodium hydroxide are used. 45% by weight.

 In the context of the preferred variant of the process of the invention, a variant according to which the addition of at least one surfactant consists of the neutralization of the free fatty acids by a base, it is also possible to use other filtration prior to filtration. surfactants and especially phospholipids, as such or in the form of the filter retentate which is recycled.

 In the case of oils difficult to refine, it may be necessary to repeat the implementation of the process of the invention, to successively carry out surfactant addition and / or neutralization steps and filtration steps for obtaining the desired result.

 Thus, it is possible in the context of the invention two successive steps of adding surfactant (s) and / or agent (s) likely (s) to generate surfactants and double filtration. For example, it may be desired to improve the result obtained by renewing the addition and / or neutralization-filtration cycle or by carrying out two "complementary" 1/2 addition and / or neutralization filtration cycles.

 According to the invention, it is therefore proposed to refine animal or vegetable oils by simple filtration since, before said filtration, there has been generated within them entities of a large volume containing the impurities to be removed.

 Said filtration is carried out through a filter whose porosity is between 0.1 and 100 μm, advantageously between 1 and 50 μm.

 At the end of said filtration, a filtrate consisting of low-phosphorus oils and a retentate rich in phospholipids and in surfactants (soaps, according to the preferred variant) are recovered on the one hand.

 The process of the invention -addition of surfactants and / or neutralization and filtration- is advantageously carried out at a temperature of less than or equal to 40 μl. Preferably, it is carried out at 20-30iC (room temperature).

 It is understood that the temperatures of each of the above steps can be different and are as low as possible to promote molecular interactions such as the formation of hydrogen bonds.

Low temperatures also limit the parasitic saponification of triglycerides. However, it is, of course, appropriate that said temperatures remain above the crystallization temperature of the treated oil. Thus, we will work at higher temperatures with oils obtained from animal fats or concrete vegetable oils.

 The filtration of the oils to which at least one suitable agent has been added according to the invention is carried out in a conventional manner. It is possible, before said filtration, to add organic and / or inorganic salts to the medium.

 Said filtration may in particular be carried out through a paper filter, a metal filter or a glass fiber filter. It can also be carried out through a mineral membrane based on ceramic for example, or organic. It can in fact be carried out with any filtering device or separation by filtration (making, for example, intervene a filter medium).

 Tangential filtration may be preferred.

It is possible to perform said filtration through a paper or metal filter whose cutoff threshold is of the order of a few microns. Very satisfactory results have been obtained in the laboratory with filters
WHATMAN N 40 and N-5 respectively having a porosity of 8 and 2.5 June.

 It is known to those skilled in the art that the efficiency of filtration can be increased by using filtering agents which generally consist of minerals of suitable particle size. The use of such agents is provided within the scope of the invention.

 This filtration is optimized by maintaining between the upstream and downstream of the filter a pressure difference sufficient to obtain a satisfactory flow without damaging the filter.

 The process of the invention can be carried out with oils without solvent or in solution in a solvent (miscella).

 Advantageously, it is carried out with solvent-free oils crude pressure oils or crude oils extracted by solvent. In the latter case, the extraction may have been carried out in a conventional manner with hexane, which is disposed of prior to the implementation of the process of the invention.

The prior solvent extraction may also have involved ethanol, isopropanol ... or a supercritical fluid. It has been found, according to the invention, that within said oils, even in the absence of a solvent, there is a combination of the phospholipids with the other surfactant molecules added or generated in situ in aggregates of sufficient size to be separated by filtration. (without using ultrafiltration).

 However, the process of the invention may also be carried out in the presence of solvent (hexane, ethanol, isopropanol, acetone, etc.) oils to be refined. In said solvent, the oil is soluble in all proportions (hexane ) or in certain proportions only (isopropanol ...). Advantageously, said solvent does not intervene in a very large quantity. It can, for example, favorably intervene, in small quantities, to reduce the viscosity of the medium and again to increase the size of the aggregates.

 The process of the invention is implemented for the refining of vegetable or animal oils, of terrestrial or aquatic origin.

 It is generally used for the refining of crude oils, i. e.

of oils released from the press or resulting directly from a solvent extraction.

Said crude oils may, however, before being refined according to the invention, for one reason or another, have undergone a chemical or physical treatment (centrifugation, for example)
The invention relates generally to a method for degumming or degumming vegetable or animal oils.

 Said process can be used for the purification of almond, peanut, borage, rapeseed, copra, jojoba, shea, flax, olive, palm, fish, castor, sesame, soy, rice bran, sunflower, tallow, lard ...

 H is advantageously used for the refining of oils used by the chemical industry (such as tallow, palm oils, copra, etc.) by the food industry (such as lard, tallow, etc.). , soybean, sunflower, palm, coconut, rapeseed, olive oils ...), by the cosmetic and pharmaceutical industry (such as almond, jojoba, borage, evening primrose, blackcurrant ...) ... and for energy purposes (such as purghere and rapeseed oils).

 The method of the invention, described throughout the present text of refining to the extent that it is generally intended to recover a purified oil (the filtrate) can, this is easily conceived, also be implemented for the recovery of retentates rich in phospholipids. Such retentates can be interesting in themselves. They can also be subjected again to the process of the invention to obtain them purer.

 The refining process according to the invention more generally consists of a process for the treatment of vegetable or animal oils.

His interest is obvious to the skilled person. It is particularly highlighted in Example 4 below.
The process of the invention has been implemented with different oils, by varying the values of some of its parameters.

 As an illustration, some of the results obtained are reproduced below.

EXAMPLE 1
Neutralized with sodium hydroxide and filtered according to the invention of crude vegetable oils.

 The study of the influence of the concentration of sodium hydroxide (NaOH at x% wt%) was carried out by applying the process to crude oils of soya, rapeseed, olive and sunflower.

 The operating conditions were as specified below.

 The stoichiometric amount of an aqueous solution of sodium hydroxide (NaOH at x to) plus 10% in excess of this same solution are added to the crude oil. The whole is mixed at 250C for 30 min and then filtered at the same temperature on WHATMAN N 40 (8 ami) filter paper.

 The characteristics of crude oils and refined oils under the conditions specified above are given in the table below.

TABLE I
INFLUENCE OF THE CONCENTRATION OF THE SODA SOLUTION ON EFFICIENCY
FILTRATION REFINING OF PLANT RAW OILS

<tb><SEP> ACID1TE <SEP> SOAP
<tb><SEP> (ppm) <SEP> (%) <SEP> (ppm) <SEP>
<tb><SEP> (%) * <SEP>
<tb> OIL <SEP> BRUTE <SEP> FROM <SEP> SOJA <SEP> 127 <SEP> 0.78
<tb> Neutralized <SEP> with <SEP> 72
<tb><SEP> NaOH <SEP> 30 <SEP>% <SEP> 10 <SEP> 0.12 <SEP> tr ** <SEP> 0.002
<tb><SEP> NaOH <SEP> 25 <SEP>% <SEP> 9 <SEP> 0.18 <SEP> tr <SEP> 0.012
<tb><SEP> NaOH <SEP> 20 <SEP>% <SEP> 12 <SEP> 0.16 <SEP> tr <SEP> 0.013
<tb><SEP> NaOH <SEP> 15 <SEP>% <SEP> 12 <SEP> 0.16 <SEP> tr <SEP> 0.076
<tb><SEP> NaOH <SEP> 10 <SEP>% <SEP> 19 <SEP> 0.09 <SEP> tr <SEP> 0.036
<tb> OIL <SEP> BRUTE <SEP> FROM <SEP> COLZA <SEP> 120 <SEP> 2.42 <SEP> ~~~ <SEP> ~~~ <SEP>
<tb> Neutralized <SEP> with
<tb><SEP> NaOH <SEP> 45 <SEP>% <SEP> 8 <SEP> 0.12 <SEP> 67 <SEP> 0.036
<tb><SEP> NaOH <SEP> 40 <SEP>% <SEP> 19 <SEP> 0.11 <SEP> 200 <SEP> 0.045
<tb><SEP> NaOH <SEP> 35 <SEP>% <SEP> 23 <SEP> 0.09 <SEP> 160 <SEP> 0.024
<tb><SEP> NaOH <SEP> 30 <SEP>% <SEP> 16 <SEP> 0.10 <SEP> 580 <SEP> 0.020
<tb><SEP> NaOH <SEP> 25 <SEP>% <SEP> 19 <SEP> 0.09 <SEP> 640 <SEP> 0.035
<tb> OIL <SEP> OF OLIVE <SEP> VIRGIN <SEP> LAMPANTE <SEP> 9 <SEP>
<tb> Neutralized <SEP> with
<tb><SEP> NaOH <SEP> 30 <SEP>% <SEP> 0.6 <SEP> 0.16 <SEP> t <SEP>
<tb> OIL <SEP> BRUTE <SEP> FROM <SEP> SUNFLOWER <SEP> 85 <SEP> 0.64
<tb> Neutralized <SEP> with
<tb><SEP> NaOH <SEP> 30 <SEP>% <SEP> 5 <SEP> 0.07 <SEP> 17 <SEP> 0.07
<tb> (*): water content and volatile matter (**) tr traces (values below 15 ppm)
Soybean and rapeseed oils have about the same phosphorus content (127 ppm and 120 ppm) but have significantly different acidities (0.78% and 2.42%).

 The best result for soybean oil is obtained with 30% NaOH.

Indeed, the oil obtained is degummed (10 ppm of P), neutralized (acidity = 0.12%), completely devoid of soaps (traces) and perfectly dry (water content = 0.002%). It should be noted that in the case of soya, the other concentrations of between 10% and 25% also give good results. This is probably due to the low acidity of this oil.

 For rapeseed oil, only the use of concentrated sodium hydroxide solution (45% NaOH) allows a good elimination of phosphorus (8 ppm), free fatty acids (0.12%), soaps (67 ppm) and moisture (0.036%); which is very satisfying. In other cases, soaps are less well eliminated.

 It can be noted that the efficiency achieved is equivalent to that obtained by conventional refining. But the latter is carried out at temperatures of the order of 60-80iC: and involves many more steps: conditioning with phosphoric acid, neutralization with sodium hydroxide, centrifugation, one to two washes with water, centrifugation and finally drying (see Example 4).

 It should also be noted that before washing with water in conventional refining, the soap content is generally between 700 and 1200 ppm and the moisture between 0.5 and 0.7%.

 Table I shows the efficiency of the process on two other oils. In the case of sunflower oil, phosphorus increased from 85 ppm to 5 ppm, acidity from 0.64% to 0.07%, soaps and moisture almost completely eliminated (respectively 17 ppm and 0 ppm). , 07%).

 Despite the high acidity of olive oil, a 30% soda solution was sufficient. Thus, the acidity fell to 0.16% and the soaps are totally eliminated. But, it should be noted that the initial phosphorus content which is very low (9 ppm) is passed after filtration to a value as low as 0.6 ppm.

EXAMPLE 2
Neutralized with sodium hydroxide and filtered according to the invention of crude vegetable oils.

 The study of the influence of the temperature of the process was carried out by carrying out said process with crude soybean and rapeseed oils. In this example, the neutralization and filtration operations were carried out at the same temperature.

 The operating conditions were as specified below.

 The stoichiometric amount of an aqueous solution of sodium hydroxide (30% NaOH for crude soybean oil, 45% NaOH for crude rapeseed oil) plus 10% excess of this same solution is added to crude oil. The whole is mixed at a temperature of xC for a certain time (2 min for soybean oil, 10 min for rapeseed oil) and then filtered at the same temperature on WHATMAN N 40 filter paper (8 ym).

 The characteristics of crude oils and refined oils under the above conditions are given in the table below.

TABLE II
INFLUENCE OF TEMPERATURE ON THE EFFICIENCY OF REFINING
BY FILTRATION OF PLANT RAW OILS

<tb><SEP> P <SEP> ACIDITY <SEP> SOAP <SEP> CONTENT
<tb><SEP> (ppm) <SEP> (%) <SEP> (ppm) <SEP> IN <SEP> WATER
<tb> OIL <SEP> BRUTE <SEP> FROM <SEP> SOJA <SEP> 136 <SEP> 0,71
<tb> Neutralized <SEP> and <SEP> filtered <SEP> to
<tb><SEP> 40 * C <SEP> 48 <SEP> 0.05 <SEP> 479 <SEP> 0.018
<tb><SEP> 600C <SEP> 67 <SEP> 0.09 <SEP> 980 <SEP> 0.015
<tb><SEP> 800C <SEP> 116 <SEP> 0.11 <SEP> 1824 <SEP> 0.008
<tb> OIL <SEP> BRUTE <SEP> FROM <SEP> COLZA <SEP> 100 <SEP> 4.3
<tb> Neutralized <SEP> and <SEP> filtered <SEP> to
<tb><SEP> 400C <SEP> 14 <SEP> 0.07 <SEP> 114 <SEP> 0.034
<tb><SEP> 600C <SEP> 19 <SEP> 0.19 <SEP> 236 <SEP> 0.045
<tb><SEP> 80 * C <SEP> 27 <SEP> 0.29 <SEP> 426 <SEP> 0.098
<Tb>
It is found that the efficiency of the filtration is affected by the rise in temperature.

 For both oils, phosphorus and soap filtrate levels increase with temperature. However, the decrease in the efficiency of the process is much less important in the case of rapeseed oil than for soybean oil. This difference in behavior is due to the neutralization time which was 10 min for rapeseed oil versus 2 min for soybean oil.

 In the case of rapeseed, the results obtained at 400C are similar to those obtained for the same oil at 250C with a neutralization time ranging from 2 to 5 min. Consequently, the duration-stirring moment during the neutralization is to be optimized according to the temperature applied during this operation.

EXAMPLE 3
The process of the invention (neutralization with sodium hydroxide and filtration) was carried out under conditions analogous to those described in Examples 1 and 2 (neutralization at 25 ° C. for 30 minutes with an aqueous solution of sodium hydroxide at 30% (amount stoichiometric + 10% excess) then filtration at 25-C), varying the nature of the filter used for filtration.

 The results obtained with a sunflower oil and a soybean oil are reproduced in the table below.

TABLE III
INFLUENCE OF THE NATURE OF THE FILTER ON THE EFFICIENCY OF REFINING
BY FILTRATION OF PLANT RAW OILS

<tb><SEP> p <SEP> ACID1TE <SEP> SOAP <SEP> CONTENT
<tb><SEP> (ppm) <SEP> (%) <SEP> (ppm) <SEP> WATER
<tb><SEP> (%)
<tb> OIL <SEP> BRUTE <SEP> FROM <SEP> SUNFLOWER <SEP> 85 <SEP> 0.64 <SEP> --- <SEP> --- <SEP>
<tb> Filtered <SEP> on <SEP> Paper <SEP> WHATMAN <SEP>
<tb> N.40 <SEP> (8 <SEP> m) <SEP> 5 <SEP> 0.07 <SEP> 17 <SEP> 0.07
<tb> Filtered <SEP> on <SEP> Paper <SEP> Creped <SEP> Industrial <SEP> 7 <SEP> 0.06 <SEP> 163 <SEP> 0.08
<tb> (42 <SEP> m) <SEP>
<tb> OIL <SEP> BRUTE <SEP> FROM <SEP> SOJA <SEP> 127 <SEP> 0.78
<tb> Filtered <SEP> on <SEP><SEP> Lipophilic Filter <SEP> GELMAN
<tb> ACRO <SEP> 50 <SEP> 14 <SEP> 0.07 <SE> tr
<tb> (0.2 <SEP> m) <SEP>
<tb><SEP> 10 <SEP> 0.12 <SEP> tr <SEP> 0.002
<tb> Filtered <SEP> on <SEP> Paper <SEP> WHATMAN <SEP> N0 <SEP> 40
<tb> (8 <SEP> Fm) <SEP>
<Tb>
The filtration of sunflower oil on industrial paper, usually used for the removal of bleaching earths during the conventional refining of oils, gives results as good as that on filter
WHATMAN N 40.

 The use of an Iipophilic GELMAN ACRO 50 filter (0.2 μm) in PITE for the filtration of a soybean oil does not bring any noticeable improvement compared to that of a WHATMAN N 40 filter (8 ce) .

 These experiments are very significant and confirm that according to the method of the invention, a simple filtration is implemented. Said filtration can moreover be implemented with filters of varied nature.

EXAMPLE 4
It has been desired to compare the efficiency of the process of the invention (preferred variant) with that of conventional refining. The following are the different steps of each of said methods:

<tb><SEP><SEP><SEP><SEP> ART <SEP><SEP><SEP> METHOD OF INVENTING
<tb> Heating <SEP> of <SEP> oil <SEP> to <SEP> 60-800C <SEP>
<tb> Addition <SEP> of <SEP> H3P04 <SEP> and <SEP> Contact
<tb> during <SEP> 15 <SEP> to <SEP> 20 <SEP> min <SEP> to <SEP>60-80'C
<tb> Neutralization <SEP> to <SEP><SEP> soda <SEP> during <SEP> 1 <SEP> Neutralization <SEP> to <SEP><SEP> soda <SEP> during <SEP> 2 <SEP > to
<tb> second <SEP> to <SEP> 15 <SEP> min <SEP> and <SEP> heating <SEP> to <SEP> 30 <SEP> min <SEP> to <SEP> ambient temperature <SEP>
<tb>70-90'C
<tb> Centnfugation <SEP> Filtration <SEP> between <SEP> 20 <SEP> and <SEP>40'C<SEP>
<tb> First <SEP> wash <SEP> to <SEP> water <SEP> hot <SEP>(90'C)
<tb> Centrifugation
<tb> Second <SEP> wash <SEP> to <SEP> water <SEP> hot <SEP>(90'C)
<tb> Centrifugation
<tb> Drying <SEP> of <SEP> oil <SEP> under <SEP> reduced <SEP> reduced
<tb> Discoloration <SEP> Discoloration
<tb> Deodorization <SEP> Deodorization
<Tb>
The process of the invention comprises only two steps to be carried out before the bleaching, ie seven less than conventional refining.

 Indeed, acid conditioning is not necessary and since the removal of phosphorus, soaps and water is obtained after filtration, the washing steps, centrifugations and drying are unnecessary.

 It therefore appears that the method of the invention allows a saving of time and very appreciable energy. In addition, it makes it possible to reduce the losses of material which are in particular inherent to the washing and centrifugation steps.

 Table IV below shows the results obtained on a refined crude soybean oil according to the conventional method (as presented above) and according to the process of the invention (as presented in Example 3 with filtration on paper WHATMAN filter N 40).

TABLE IV
REFINING SOY OIL WITH CLASSIC REFINING
AND BY THE PROCESS OF THE INVENTION

<tb><SEP> P <SEP> SOAP <SEP> ACID
<tb><SEP> (ppm) <SEP> (ppm) (%)
<tb> OIL <SEP> BRUTE <SEP> FROM <SEP> SOJA <SEP> 127 <SEP> --- <SEP> 0.72
<tb> Refining <SEP> Chemical <SEP> Classical <SEP> 18 <SEP> 131 <SEP> 0.22
<tb> Refining <SEP> with <SEP> filtration <SEP> 10 <SEP> tr <SEP> 0.12
<Tb>
The soybean oil obtained by filtration is soap-free and contains 10 ppm phosphorus and 0.12% moisture, whereas conventional chemical refining gives after the second washing step an oil containing 18 ppm of phosphorus, 131 ppm of phosphorus. soaps and 0.22% water.

 This comparison shows the efficiency of the process of the invention compared to that of conventional refining.

Claims (11)

1. Process for refining vegetable or animal oils, characterized in that it comprises:  adding to said oils at least one surfactant and / or at least one agent capable of generating, within them, a surfactant;  filtering the mixture through a filter whose porosity is between 0.1 and 100 μm, advantageously between 1 and 50 μm;  - The recovery of filtrates consisting of low phosphorus oils and retentates rich in phospholipids. 2. Method according to claim 1, characterized in that it comprises:  neutralizing said oils with at least one appropriate base;  - Filtration of said neutralized oils through a filter whose porosity is between 0.1 and 100 Jan; advantageously between 1 and 50 μm;  the recovery of filtrates consisting of neutral oils with a low content of phosphorus and of free fatty acids and retentates rich in phospholipids and soaps. 3. Method according to claim 2, characterized in that, for the neutralization of said oils, is added the stoichiometric amount plus 10% in excess of a strong aqueous base solution, preferably an aqueous solution of sodium hydroxide. 4. Method according to one of claims 2 or 3, characterized in that for the neutralization of oils with an acidity of less than 1%, aqueous solutions of sodium hydroxide 30% by weight are used and, for the neutralization of oils with acidity greater than 1%, aqueous sodium hydroxide solutions at 45% by weight. 5. Method according to any one of claims 1 to 4, characterized in that it is carried out with the addition of phospholipids and / or recycling the retentate upstream of the filtration. 6. Method according to any one of claims 1 to 5, characterized in that it comprises two successive stages of addition of surfactant (s) and / or agent (s) likely (s) to generate surfactants. 7. Method according to any one of claims 1 to 6, characterized in that addition and / or neutralization and filtration are carried out at a temperature less than or equal to 40 ° C; advantageously at a temperature between 20 and 30in. 8. Method according to any one of claims 1 to 7, characterized in that the filtration is carried out through a paper filter, a metal filter or glass fiber, or through a mineral or organic membrane; advantageously through a paper filter or a metal filter. 9. Process according to any one of claims 1 to 8, characterized in that it is carried out with oils without solvent or in solution in a solvent. 10. Process according to claim 9, characterized in that it is carried out with crude pressure oils or crude oils extracted by solvent. 11. Process according to any one of Claims 1 to 10, characterized in that it is carried out with almond, peanut, borage, rapeseed, coconut, jojoba and shea oils. flax, olive, palm, fish, castor, sesame, soy, rice bran, sunflower, tallow or lard ...