EP1240284A1

EP1240284A1 - Method for extracting and fractionating fats with solvent, using at least a hydrofluroether

Info

Publication number: EP1240284A1
Application number: EP00993521A
Authority: EP
Inventors: Benoít LEMAIRE; Michel Surbled; Jacques Swegers; Bernard Mompon
Original assignee: Extractive
Current assignee: Extractive
Priority date: 1999-12-21
Filing date: 2000-12-21
Publication date: 2002-09-18
Also published as: FR2802547B1; CN1425057A; BR0016548A; CA2395559A1; AU2857601A; WO2001046354A1; JP2003518160A; US6673952B2; FR2802547A1; US20030091709A1

Abstract

The invention concerns a method for extracting and fractionating fats contained in a raw material, characterised in that it comprises at least a step which consists in using an extraction solvent consisting of at least a hydrofluoroether of general formula (I): CnF 2n+1 O Cm H2m+1, wherein: n ranges between 3 and 6 and m ranges between 1 and 5 and at least a separation step enabling to obtain a raw extract of fats rich in unsaponifiable substances and optionally, in free fatty acids and a insoluble extraction fraction.

Description

Process for the extraction and fractionation of fat by solvent, using at least one hydrofluoroether.

The invention relates to the field of extraction chemistry. More specifically, the present invention relates to the extraction of fats from natural raw materials.

Fats, mainly those of vegetable origin, are ingredients widely used by the food, cosmetic and pharmaceutical industries.

These fats can however rarely be used in the raw state and must generally be subjected to refining in order to remove one or more undesirable constituents, the nature of which depends on the applications envisaged for the refined product.

Thus, the cosmetic and pharmaceutical industries use fats enriched with unsaponifiable matter, that is to say, according to French standard NFT 60-205-1 in substances which, after saponification of the fat by potash and extraction by a specified solvent, are not volatile under specified conditions. Fats enriched in unsaponifiables have particularly high contents of hydrocarbons, heavy alcohols (aliphatic or terpene), sterols and tocopherols and are obtained after elimination of part of the triglycerides which are the main constituents of crude fat. Among the many extraction and fractionation processes for fatty substances proposed in the state of the art, solvent extraction is a very widespread technique which is available according to numerous technological variants.

Thus, patent application FR 2 702 773 proposes a process for the preparation of vegetable fat fractions enriched with unsaponifiable matter. In this process, the vegetable fat is treated with acetone in order to recover, on the one hand, a hot insoluble fraction, rich in unsaponifiable matter, and, on the other hand, a soluble fraction, subjected subsequently to a step of cold crystallization. After filtration of the precipitate, the filtrate is evaporated to dryness. The evaporation residue also constitutes a fraction enriched with unsaponifiable matter. The precipitate, on the other hand, is enriched in triglycerides. It will be noted that, depending on the raw material from which they are extracted, vegetable fats have different compositions, qualitatively and quantitatively.

These differences may justify the use of solvents other than acetone (for example hexane or ethanol), both in the hot extraction stage and in the cold precipitation stage. .

The main drawback of the solvent extraction and fractionation process results from the use of organic solvents (alkanes, ketones, esters, alcohols, ethers, chlorinated solvents) which subject the extract obtained to regulatory constraints relating to residual solvent contents. Indeed, whatever their nature, these organic solvents are either harmful or toxic. This harmfulness and this toxicity manifest themselves at generally low contents of residual solvents in the extracts obtained. In order to eliminate health risks, it is therefore necessary to implement desolvantization processes which have several drawbacks. Indeed, in addition to the additional cost that they induce, these desolvantization processes can have, depending on the operating conditions applied, a negative impact on the quality of the extracts thus treated.

These constraints also relate to the risks of discharging solvents, into the natural environment, in liquid or gaseous form. Finally, with the exception of alkanes, traditional extraction solvents have the disadvantage of having a non-total chemical inertness, which risks leading, depending on the conditions of extraction or storage of the extracts, to denaturation of the products. obtained.

The main objective of the present invention is to provide a method for extracting and fractionating fat by solvent which does not have such drawbacks. Such a method according to the invention is characterized in that it comprises at least one step using an extraction solvent consisting of at least one hydrofluroether (abbreviated to HFE) of general formula (I): _n ^ _{2n +} ι _m H _{2m + 1} in which, n is between 3 and 6 and m is between 1 and 5 and at least one separation step leading to the obtaining of a part of a crude extract of matter fatty rich in unsaponifiable substances and, possibly, in free fatty acids and on the other hand to an insoluble fraction of extraction.

These hydrofluoroethers have, compared to conventional solvents, the following advantages compared to conventional solvents. They are non-flammable and do not therefore require the use of special production and protection equipment. This characteristic is particularly interesting in production prospects on an industrial scale since it has a direct impact on the cost of finished products;

They do not present a risk for the ecosystem and are in compliance with the strictest environmental regulations (zero destruction potential of the ozone layer and very low contribution to the greenhouse effect);

They are chemically inert, odorless, colorless and tasteless. They therefore have no negative impact on the properties of the extracts or formulations which contain them or which they were used to prepare. Even in large doses, they are non-toxic by inhalation, adsorption or repeated contact;

Finally, they have a low calorific capacity and latent heat of vaporization compared to those of organic solvents commonly used in extraction; the process according to the invention is therefore inexpensive in energy. Preferably, said hydrofluoroether is chosen from methoxynonafluorobutane of formula C ₄ F ₉ -O-CH ₃ (also designated in the chemical industry by the name HFE7100) and ethoxynonafluorobutane C ₄ F ₉ -OC H ₅ (also designated in the chemical industry by the name HFE-7200).

These compounds have the advantage of having boiling points of 60 ° C for methoxynonafluorobutane and 78 ° C for ethoxynonafluorobutane which allow their use in traditional solid-liquid or liquid-liquid extraction equipment. , without notable modifications of these. These hydrofluoroethers can also be used in extraction processes using new technologies such as microwaves or ultrasound. It will be noted that the use of hydrofluoroethers as extraction agents has already been described in PCT patent application FR98 / 02546. This document discloses the solubilizing nature of HFEs for the preparation of plant extracts without, however, highlighting, unlike the present invention, the particularly selective character of these HFEs with respect to the particular classes of chemical compounds that are the rich lipid fractions. in unsaponifiable matter.

On the other hand, the present invention demonstrates that the HFEs are capable of extracting, with good selectivity, such lipid fractions rich in unsaponifiable matter. It will be noted that this selectivity is not total since the HFEs of formula (I) co-extract lipid substances which do not belong to the category of unsaponifiable matters, in particular triglycerides and free fatty acids. The coextraction of free fatty acids constitutes in some cases an additional advantage of the process, particularly in the case of matrices containing free fatty acids of pharmaceutical, cosmetic or nutritional interest.

According to a preferred variant of the invention, it is possible to enrich the crude fat extract obtained, rich in unsaponifiable substances and in free fatty acids, by a step of selective precipitation of the co-extracted triglycerides consisting in cooling said extract. crude at a temperature below the extraction temperature. The method according to the invention therefore makes it possible to fractionate the fat into fractions enriched in unsaponifiable matter and in free fatty acids and in fractions enriched in triglycerides.

The fractions obtained can be suitable for cosmetic applications as well as pharmaceutical or food applications. According to a preferred variant of the invention, the method comprises an additional step consisting in decanting said filtrate and then evaporating it so as to recover a soluble extract very enriched in unsaponifiable substances and in free fatty acids.

According to another advantageous aspect of the process according to the invention, said insoluble fraction is recycled at the start of the process. It will be noted that the method according to the invention can be implemented in the presence of at least one co-solvent chosen from alkanes, ketones, alcohols, alkyl ethers, carboxylic acids, esters, amides , halogenated hydrocarbons, acetals. The invention, as well as the various advantages which it presents, will now be more easily understood thanks to the description which will follow of non-limiting examples of embodiment thereof.

Example 1 - Fractionation of shea butter into a fraction enriched in triglycerides and a fraction enriched in unsaponifiable shea butter (20 g), titrated at 7-8% unsaponifiable, is stirred at 40 ° C. for

1:30 in 2 liters of ethoxynonafluorobutane (C ₄ F ₉ -OC, H ₅ ). After stirring has stopped, the suspension is left to settle for 20 minutes. The fluorinated phase is then separated from the insoluble extraction and then cooled to 8 ° C. After 2 hours of decantation, the cooled suspension is filtered through a 10 μm mesh fabric. The clear filtrate is evaporated to dryness.

The qualitative analysis of the fractions is carried out by thin layer chromatography (silica) using an eluent hexane / ethyl ether / acetic acid in the volume proportions 90/10 II. The deposits correspond to 6 μl of hexane solutions at 20 mg / ml. The plates are dried and then revealed with ethanol at 5% sulfuric acid (drying at 110 ° C). The results clearly show that the EP fraction (precipitated extract) consists almost exclusively of triglycerides. On the other hand, the ES fraction (soluble extract) is very rich in unsaponifiable substances (karitene, sterols and fatty alcohols in particular). These results are summarized in Table 1 below.

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Example 2 Extractions Compared by Soxhlet of Cocoa Cakes with Hexane and with Ethoxynonafluorobutane

This example is intended to provide an element of comparison with regard to the extraction yields with hexane and the extraction yields with ethoxy nonafl uorobutane.

Cocoa cake (50 g) is extracted in a Soxhlet for 5 hours with hexane. After extraction, the hexane extract is evaporated and the extract yield is calculated on the basis of the weight of cake used.

Cocoa cakes (50 g) are extracted in Soxhlet for 5 hours with ethoxynonafluorobutane (C ₄ F ₉ -OC ₂ H ₅ ). After extraction, the extract is cooled to room temperature (20 ° C). This operation makes it possible to decant an insoluble fraction. After elimination of the insoluble fraction, the fluorinated under-swimming is evaporated. The yields of insolubilized extract and of soluble extract are calculated on the basis of the weight of oil cakes used.

The compared results of the extraction with hexane and, according to the invention, of the extraction with ethoxynonafluorobutane, are given in table 2 below.

Table 2 Example 3 - Extraction of cocoa cake by ethoxynonafl uorobutane in 4 successive extractions

Cocoa cake (500 g) is extracted with stirring, at 65 ° C, for 1H3O, with 2 liters (2.86 kg) of ethoxynonafluorobutane (C ₄ F ₉ -OC ₂ H ₅ ). The suspension is quickly filtered on a 10 μm mesh filter cloth. The filtrate is cooled to 20 ° C. in order to precipitate an insoluble material as in Example 2. The insoluble material is filtered through a filter fabric of 10 μm mesh. The intermediate yield in insoluble fraction is calculated on the basis of the weight of oil cakes used. The filtrate obtained is returned to the extractor for a new extraction cycle using the insoluble material from the previous extraction. In total, four extraction cycles are carried out according to the same operating mode. At the end of the last cycle, the final filtrate (separated from the insoluble material precipitated at 20 ° C) is evaporated under reduced pressure. The yield of soluble materials is expressed relative to the weight of oil cakes used. The results are specified in Table 3 below.

Table 3

The extracts insolubilized at 20 ° C are yellow in color. The soluble extract is lighter with a strong cocoa odor.

The qualitative analysis of the fractions is carried out by thin layer chromatography (silica) using an eluent hexane / ethyl ether / acetic acid 90/10/1. The deposits correspond to 6 μl of hexane solutions at 20 mg / ml. The plates are dried and then revealed with ethanol at 5% sulfuric acid (drying at 110 ° C). The results indicate that the insolubilized extracts are enriched in triglycerides and that the soluble matters of the final filtrate are on the other hand enriched in unsaponifiable matters. A much higher content of free fatty acids is also observed in the soluble materials of the final filtrate than in the insolubilized extracts. The examples described above with reference to shea butter and cocoa illustrate some possible applications of the present invention and do not limit the scope of the present invention. Indeed, the fractionation by hydrofluoroethers can be applied to many other fats or natural matrices known for their lipid profile as well as for their uses for mainly cosmetic, pharmaceutical or food purposes (in particular avocado, wheat germ oil, oil pumpkin and pumpkin seeds, savv palmeto fruits (Serenoa repens), bark of Pygeum africanum (Prunus africana). The invention may also be applied to animal raw materials, raw materials of animal origin (milk and derivatives, egg products, lanolin, beeswax, etc.) as well as single-celled organisms (yeasts, fungi, bacteria).

EXAMPLE 4 Fractionation of Shea Butter with Ethoxynonafluorobutane

This example describes the influence of various operating parameters on the fractionation of shea butter by ethoxynonafluorobutane (HFE7200). These parameters are the extraction temperature, the extract reprocessing temperature and the number of extraction cycles carried out on the same charge of shea butter 50 g of shea butter (titrating 6.5% unsaponifiable) are extracted by 2 liters of ethoxynonafluorobutane with gentle stirring for 30 minutes and at the extraction temperature T _E (50 or 70 ° C). After decantation, the two-phase medium is separated into a crude extract (EB1) and a raffinate. The raffinate is subjected twice more to the same extraction operating procedure, making it possible to obtain two other crude extracts (EB2 and EB3). The three crude extracts (EB 1, EB2 and EB3) are stored overnight at a precipitation temperature T _p (4 ° C or room temperature) in order to cause the precipitation of part of the triglycerides and, thus, to increase the unsaponifiable content of fluorinated extracts. After separation of the precipitates and the supernatants, then elimination of the solvent, there are obtained, respectively, 3 precipitated extracts, denoted EPI, EP2 and EP3, and 3 soluble extracts, denoted ES 1, ES2, ES3.

The indicators making it possible to evaluate the influence of the three operating parameters are the mass of the soluble extracts ESI, ES2 and ES3, the unsaponifiable content of the soluble extracts ESI, ES2 and ES3, the mass of unsaponifiable extract, present in the ESI extracts , ES2 and ES3, and the mass of the precipitated extracts EPI, EP2 and EP3. Table 4 below shows the influence of these three operating parameters.

Table 4

The results according to this table indicate that: the amount of soluble extract depends only on the precipitation temperature. It increases with T _p and decreases with each extraction cycle. the unsaponifiable content only depends on the precipitation temperature. It increases when T _p decreases and it decreases with each extraction cycle, the mass of extractable unsaponifiable matter remains approximately constant, whatever the extraction and precipitation temperatures. It decreases with each extraction cycle, the quantity of precipitated extract only depends on the extraction temperature. It increases with T _E and also remains constant whatever the extraction cycle.

The critical parameter is therefore the precipitation temperature: "for a low precipitation temperature (ex: 4 ° C), the extraction will be selective

(high unsaponifiable content) but not very effective (low quantity of soluble extract) "for a high precipitation temperature (eg ambient T), the extraction will be effective (high quantity of soluble extract) but not very selective (medium content unsaponifiable)

It will be noted that the most selective extraction (T _p = 4 ° C; 1 ^st extraction cycle) leads to an unsaponifiable content of the extract of the order of 50%. The enrichment factor is therefore around 7.7. EXAMPLE 5 Fractionation of Shea Butter with Ethoxynonafluorobutane

(ΗFE7200) at 50 ° C - Influence of the precipitation temperature

Example 4 showed that the extraction temperature had no significant influence on either the selectivity or the efficiency of the extraction. Consequently, in this example, the shea butter is treated at an extraction temperature of 50 ° C., just above its liquefaction temperature.

The extraction procedure is identical to that of Example 4, except for the precipitation temperatures: -18 ° C, 4 ° C and room temperature.

Table 5 The results according to Table 5 indicate that: as in the previous example, the quantity of soluble extract increases with T _p and decreases with each extraction cycle as in the previous example, the unsaponifiable content increases when T _p decreases and it decreases with each extraction cycle. as in the previous example, the mass of unsaponifiable matter extracted remains approximately constant, whatever the precipitation temperature. It decreases with each extraction cycle "Contrary to what the previous example demonstrates, the quantity of precipitated extract becomes dependent on the precipitation temperature. It increases when T _p is lowered to -18 ° C. On the other hand, it remains constant whatever the cycle d The general conclusions remain unchanged:

¹ for a low precipitation temperature (ex: -18 ° C), the extraction will be selective (high unsaponifiable content) but ineffective (low quantity of soluble extract)

¹ for a high precipitation temperature (ex: ambient T), the extraction will be effective (high quantity of soluble extract) but not very selective (average unsaponifiable content).

It will be noted that the most selective extraction (T _p = -18 ° C; 1 ^st extraction cycle) leads to an unsaponifiable content of the extract of around 70%. The enrichment factor is therefore around 10.7.

Claims

1. Method for extracting and fractionating fatty matter contained in a raw material, characterized in that it comprises at least one extraction step using an extraction solvent constituted by at least one hydrofluroether of general formula ( I):

C _n ^F ₂ „ ₊ ι ° C _m H _{2m + 1} in which, n is between 3 and 6 and m is between 1 and 5 and at least one separation step leading to obtaining a share of a crude extract of fatty matter rich in unsaponifiable substances and, possibly, in free fatty acids and on the other hand to an insoluble fraction of extraction.

2. Method according to claim 1 characterized in that said hydrofluoroether is chosen from methoxynonafluorobutane (C ₄ F ₉ -O-CH ₃ ) and ethoxynonafluorobutane (C ₄ F ₉ -OC ₂ H ₅ ).

3. Method according to one of claims 1 or 2 characterized in that it comprises a step of selective precipitation of the triglycerides present in said crude extract consisting of cooling said crude extract to a temperature below the extraction temperature., Then filtering said raw extract to obtain a precipitated extract and a filtrate.

4. Method according to claim 3 characterized in that it comprises an additional step consisting in decanting said filtrate and then evaporating it so as to recover a soluble extract.

5. Method according to any one of claims 1 to 4 characterized in that said insoluble fraction is recycled at the start of the process.

6. Method according to any one of claims 1 to 5 characterized in that it is implemented in the presence of at least one co-solvent chosen from alkanes, ketones, alcohols, alkyl ethers, carboxyhque acids, esters, amides, halogenated hydrocarbons, acetals.