New process for preparing cashew nut shell oil

Abstract

The invention relates to the use, for the implementation of a solvent extraction process of an extract containing or consisting of a natural or technical CNSL oil and possibly tannins from cashew nut shells, in particular ground, of a continuous introduction into an extractor of cashew nut shells, in particular ground, constituting the extraction material, causing the passage of said extraction material from the inlet of the extractor enclosure to the outlet of said extractor enclosure, said introduction being carried out against the direction of the flow of said solvent, said extraction material forming with the solvent a porous system, and the corresponding process.

Description

Title of the invention: New process for preparing oil of cashew nut shells

[0001] The present invention relates to a new process for preparing cashew nut shell oil. The invention also relates to a new cashew nut shell extract containing or consisting of a natural or technically produced CNSL oil and optionally tannins. CONTEXT OF THE INVENTION

[0002] Cashew nuts comprise 55 to 65% by weight of shells and 35 to 45% by weight of kernel. Cashew nut shells are therefore an agricultural waste product generated by cashew nut processing plants and thus an inexpensive raw material. In particular, cashew nut shells contain a dark reddish-brown caustic oil, on the order of 15 to 40% by weight, rich in phenolic lipids, and have potential for the production of high-value-added fuels and chemicals, providing an eco-responsible and local alternative to products from the petroleum industry.

[0003] Cashew Nut Shell Oil, or CNSL, is a natural oil derived from cashew nut shells. The main components of crude CNSL are phenolic compounds: anacardic acid, cardol, and cardanol. Methyl cardol is also present, but in trace amounts (< 5%).

[0004] Each of these compounds is itself a mixture of products, comprising an alkyl or alkenyl chain, said alkenyl chain having 1, 2 or 3 double bonds (Scheme 1):

[0005] [Chem.l] anacardic acid 65% cardol 15 to 20% methyî cardol cardanol trace 10%

[0006] Scheme 1 - chemical structures of the main constituents of natural CNSL.

[0007] The CNSL can be classified into 2 types, depending on the extraction method used: • Natural CNSL, an extract obtained by extraction using a low-boiling-point solvent or obtained mechanically without heating, • CNSL technique, obtained by hot processes, in particular by high-temperature roasting, e.g. >200°C.

[0008] Technical CNSL contains a reduced amount of anacardic acid compared to natural CNSL, due to partial decarboxylation during heating or roasting. In some cases, the decarboxylation is even complete, and the CNSL no longer contains any anacardic acid.

[0009] By "crude undecarboxylated CNSL" or "natural CNSL" is therefore meant a CNSL that has not undergone, or has only partially undergone, decarboxylation of anacardic acid. Crude undecarboxylated CNSL is thus characterized by the presence of anacardic acid as the major species in the mixture.

[0010] To date, the valorization of CNSL oil is a promising avenue given the potential presented by the components which constitute it.

[0011] The qualification of natural or technical CNSL therefore depends on the composition of the different components in particular the level of anacardic acid and consequently on the extraction method used to obtain the oil.

[0012] Various mechanical, thermal or chemical extraction techniques using a solvent are known, from cashew nut shells to obtain natural or technical CNSL.

[0013] Mechanical extraction by compression using a press is effective and yields natural CNSL rich in anacardic acid, but its yield is limited because significant quantities of oil, on the order of 10 to 15% by weight, remain trapped in the residues after pressing. Furthermore, mechanical extraction results in higher viscosities of the extracted material, which promotes clogging problems and also contributes to thermo-oxidative instability, as the extracted materials can be subjected to temperature increases during pressing, promoting the decarboxylation of anacardic acid.

[0014] Thermal extraction or pyrolysis involves the application of heat, which converts most of the anacardic acid into cardanol, producing technical CNSL. The technique is suitable if a cardanol-rich CNSL is desired.

[0015] Mechanical and / or thermal extraction techniques are predominantly used to produce CNSL on an industrial scale, despite their disadvantages described above.

[0016] Cold or hot extraction with a solvent involves a large amount of solvent which involves considerations regarding its toxicity, recycling and origin (petro- or bio-based),

[0017] leading to environmental and health problems.

[0018] Methods for extracting CNSL using supercritical fluids have been implemented. So-called green solvents such as water and carbon dioxide can be used and offer an environmental advantage. However, such an extraction method requires an energy-intensive device due to the necessary operating conditions of temperature and / or pressure.

[0019] Solvent extraction methods have the advantage of achieving oil residues in the press cake at a content of less than 1% by weight. However, they are generally carried out in batches, involving large volumes of solvent to manage and thus limiting their use on industrial volumes and in a continuous industrial process.

[0020] Many extraction methods can be implemented to extract oils from plants, but it is important to note that the quality and quantity of the extracted solutes depend on the association, or even the synergy, between the method used and the characteristics of the extraction device and the nature of the plants.

[0021] There is a need to valorize cashew nut shells by an extraction process allowing to obtain an oil comprising high value added compounds such as CNSL oil and tannins contained in cashew nut shells and to obtain a material after extraction, the press cake, as natural and ecological alternatives to petrochemical products.

[0022] There is a need to use an extraction method allowing continuous extraction of cashew nut shells for industrial purposes and needs under unconstrained temperature and pressure conditions, and in an environmentally responsible manner.

[0023] There is a need to improve and optimize the extraction yield of an extract containing or consisting of natural or technical CNSL oil possibly including other substances of interest such as tannins.

[0024] There is a need to obtain a natural CNSL oil rich in anacardic acid.

[0025] One of the aims of the invention is the use of a suitable extraction process for obtaining cashew nut shell oil.

[0026] Another object of the invention is a high-performance, efficient industrial extraction process that can be operated continuously.

[0027] Another object of the invention is the obtaining of a natural or technical CNSL oil.

[0028] Another object of the invention is the obtaining of tannins from walnut shells cashew.

[0029] Another object of the invention is the obtaining of a cake that can be valorized.

[0030] A first object of the present invention is the use, for implementation of a solvent extraction process of an extract containing or consisting of a natural or technical CNSL oil and possibly tannins from cashew nut shells, in particular ground, of a continuous introduction into an extractor of cashew nut shells, in particular ground, constituting the extraction material, causing the passage of said extraction material from the inlet of the extractor enclosure to the outlet of said extractor enclosure, said introduction being carried out against the direction of the flow of said solvent, said extraction material forming a porous system with the solvent.

[0031] In the case of cashew nut shells, the inventors have surprisingly discovered that the extraction material, consisting of cashew nut shells, particularly ground ones, forms a porous system with an extraction solvent, allowing a yield similar to batch extraction and / or extraction requiring temperature and pressure constraints. Such a porous system allows continuous introduction into an extractor and the implementation of a countercurrent extraction process with the extraction solvent under mild temperature conditions, i.e., below 140°C, and pressure conditions, i.e., at atmospheric pressure. Advantageously, the use of this porous system does not require overpressure of the extraction solvent.

[0032] Thus, this discovery on the adaptability of cashew nut shells to continuous solvent extraction leading to optimized yields opens up the possibility of implementing an industrializable continuous liquid / solid extraction process under ambient conditions, i.e., not constrained in temperature and pressure, allowing the processing of industrial quantities on the order of a ton of cashew nut shells and the continuous production of CNSL oil.

[0033] Such a process makes it possible to manage and control simultaneously the flows of material and solvent used and thus to optimize the yield of oil extracted and the volume of solvent used.

[0034] The cashew nut consists of an outer shell, a fitted inner shell, a testa and a kernel.

[0035] The term “cashew nut shell” means the parts of the nut that differ from the kernel.

[0036] The term “crushed cashew nut shell” means the fragmented parts of the nut that differ from the kernel.

[0037] The cashew nut comprises approximately 55 to 65% by weight of shells and 35 to 45% by weight of kernel. The cashew nut shell contains a caustic, dark reddish-brown (15-40%) CNSL oil rich in non-isoprenoid phenolic lipids. The cashew kernel is edible and has a high protein content (19.5%), ranking third in production. global edible nuts.

[0038] Cashew nut shells are in particular agricultural waste generated by cashew nut processing plants.

[0039] The term "extraction material" means material, in solid form, composed of cashew nuts, in particular ground, comprising compounds of interest miscible in an extraction solvent, which is intended to undergo treatment to extract said compounds of interest.

[0040] The term "extract" means all the compounds of interest that can be extracted during an extraction process.

[0041] The term "solute" means the compounds of interest contained in the extraction material that are miscible in a solvent and that can be extracted by a solvent extraction process.

[0042] The term “solvent” means a liquid in which at least one of the compounds derived from cashew nut shells can be dissolved.

[0043] The term "porous system" refers to the system generated by the shells, particularly crushed cashew nuts, with the solvent during extraction. This system exhibits porosity and a tortuous nature of solvent displacement during extraction, which define the kinetics of solute dissolution in the solvent and influence the liquid / solid extraction.

[0044] Indeed, the system composed of intertwined cashew nut shells is generally similar to a porous material, into which the solvent can infiltrate. The sizes, interstitial volumes, and densities of the cashew nut shells thus constitute intrinsic parameters of this porous system, since they will influence the diffusion of the solute from the plant material to the solvent and consequently the CNSL extraction process.

[0045] The term "interstitial volume" refers to the volume accessible to the solvent within the interstices of the extraction material, which consists of cashew nut shells, particularly ground cashew nut shells, forming the porous system. For example, the porous system is considered to consist of ground cashew nut shells with an average particle size of 1 mm to 1 cm mixed with a solvent that reaches the surface of the shells. The system is not agitated. Thus, the interstitial volumes are between approximately 15% and approximately 60% of the total volume of the porous system.

[0046] Cashew nut shell extract contains CNSL compounds and may contain tannins.

[0047] The term “tannin” refers to a compound in the polyphenol family found in cashew nut shells.

[0048] Tannins are compounds found in the majority of plants. Some of them have been known for centuries and are used in many fields.

[0049] Structurally, they can be classified into three categories:

[0050] - Hydrolyzable tannins, which are composed of gallic acid (gallotanin) or of hexahydroxydiphenic acid (ellagitannin) chemically linked to one or more polyols or sugars or terpenoids.

[0051] - Condensed tannins, which are made up of oligomers or polymers of catechin (also called flavanol).

[0052] - Complex tannins, which consist of a catechin unit linked to a motif gallotanin or ellagitanin.

[0053] The tannins contained in the cashew nut shell are composed in particular of gallic acid and gallic acid derivatives, as well as flavonoids (such as leufoline and isohemiphloin). For the purposes of the present invention, the CNSL compounds (anacardic acid, cardanol, cardol, and methylcardol) are not considered tannins because they are not chemically bound to polyols or to catechin oligomers / polymers.

[0054] The extractor is defined as a device enabling the implementation of the process of the invention.

[0055] The extractor for the continuous extraction process comprises a housing equipped with:

[0056] - an inlet end for introducing the extraction material,

[0057] - of an outlet end intended for the evacuation of the extracted material, after extraction of it.

[0058] The term "the flow of the extracted material from the inlet of the chamber to the outlet of the extractor chamber" refers to the transport, within the extractor chamber where the extraction process takes place, by means of the extractor's technical components such as a screw conveyor, of the extracted material from an inlet of the chamber intended for introduction to an outlet intended for removal of the material after extraction. The direction of the flow, corresponding to that from the inlet to the outlet of the chamber, defines the direction of introduction of the extracted material.

[0059] The direction of the solvent flow in the extractor is defined as the direction of solute enrichment of the solvent which is parallel to the direction of introduction of the extraction material.

[0060] The term "counter-current" means that the direction of introduction of the extraction material and that of the solvent flow in the extractor are in opposite directions.

[0061] Advantageously, in the countercurrent extraction process, the freshly introduced extraction material is brought into contact with the solute-enriched solvent, which is about to leave the extractor chamber. The fresh solvent entering at the other end of the extractor is in contact with the solute-depleted extraction material.

[0062] The counter-current makes it possible to maintain a practically constant exchange potential throughout the extractor and can thus reduce the amount of solvent used and in as a consequence the price of separating the solutes and the solvent and that of regenerating the solvent.

[0063] According to a particular embodiment, the present invention relates to the use as defined above, in which the extraction process is carried out by percolation of the solvent through the extraction material or by immersion of the extraction material in the solvent.

[0064] According to a particular embodiment, the present invention relates to the use as defined above, in which the extraction process is carried out by percolation of the solvent through the extraction material.

[0065] The term "percolation" refers to a liquid / solid extraction of a solute from a solid-phase extraction material using an extraction solvent, which is defined as a liquid that solubilizes said solute. Percolation consists of passing the liquid through a medium containing said extraction material that is permeable to said liquid. The solid phase is traversed by a liquid, unsaturated with solute, allowing the extraction of said solute without saturation problems. It also helps to limit the potential thermal degradation of the extracted compounds.

[0066] Percolation has the advantage of being implementable using a solvent dispersion nozzle and being applicable at several points within the extractor chamber. Since the extractor is equipped with internal filtration systems, percolation does not require additional filtration and / or clarification steps. Furthermore, percolation extraction devices are compact, which facilitates their deployment on an industrial scale (saving space / floor area).

[0067] According to a particular embodiment, the present invention relates to the use as defined above, in which the extraction process is carried out by immersing the extraction material in the solvent.

[0068] "Immersion extraction" refers to a liquid / solid extraction process that involves covering or immersing the extraction material with the extraction solvent. The immersion of the extraction material can be sequential, meaning with controlled immersion times in sequences, and / or partial, meaning that the extraction material is partially covered (at least 50%, and in particular from 50% to 100%) by the solvent. The extraction material can be agitated during the process, which promotes diffusion of the solute in the extraction solvent. Furthermore, immersion extraction has the advantage of ensuring a homogeneous residence time of the extraction material in the solvent.

[0069] The two immersion methods, namely sequential and partial, can be used simultaneously.

[0070] The two extraction methods, namely percolation and immersion, can also be adapted simultaneously.

[0071] According to a particular embodiment, the present invention relates to the use as defined above, in which the extraction process is carried out in an extractor having several stages, in particular N stages, N varying from 2 to 10, preferably N equal to 4. For example N is equal to 2, 3, 4, 5, 6, 7, 8, 9 or 10, in particular 4, 6 or 10.

[0072] According to a particular embodiment, the present invention relates to the use as defined above, in which the extraction process is carried out in a pilot extractor comprising 3 to 6 stages, preferably 4 stages.

[0073] According to a particular embodiment, the present invention relates to the use as defined above, in which the extraction process is carried out in an industrial-scale extractor comprising 3 to 10 stages.

[0074] The inventors also found for the porous system generated by the cashew nut shells and the extraction solvent, contrary to expectations, that a limited number of solvent extraction steps, namely less than 4 steps, could be carried out to extract almost all of the CNSL contained in the cashew nut shells, in particular ground.

[0075] The term "stage" refers to a segment of the extractor comprising means for carrying out an extraction step. It is understood that an extractor may contain several successive stages configured to allow successive extraction steps on the extraction material.

[0076] In the extractor the stages can be configured to follow one another along a longitudinal axis of the extractor, which can be oriented horizontally or vertically.

[0077] Another object of the present invention is a process for preparing an extract containing or consisting of a natural or technical CNSL oil and optionally tannins by solvent extraction from cashew nut shells, in particular ground, comprising the following steps:

[0078] a) a step of introducing cashew nut shells, in particular crushed, constituting the extraction material, continuously into an extractor, causing said extraction material to pass from the inlet of the extractor chamber to the outlet of said extractor chamber,

[0079] b) an extraction step of a solute contained in the extraction material, said step comprising N extraction step(s) by a solvent during the passage of said extraction material through the extractor, N varying from 2 to 10, said extraction material and the solvent forming a porous system,

[0080] in which the direction of said introduction is counter-current to that of the solvent flow,

[0081] wherein for each extraction step i, i varying from 1 to N, leads to obtaining an extracted liquid phase i containing a solute i and the solvent, said solute forming a miscella i with the solvent, which miscella i is collected in a reservoir i,

[0082] c) a recovery step:

[0083] - of each of the aforementioned miscella i, i varying from 1 to N, in a reservoir F to obtain said extract containing or composed of CNSL and possibly tannins and

[0084] - possibly oilseed cake, resulting from the extraction material after step b) extraction of the solute, at the outlet of the extractor chamber.

[0085] The term "solute" means the compounds of interest contained in the material to be extracted and which are miscible in the extraction solvent.

[0086] The term "miscella" means the solution obtained from an extraction consisting of the solute and the solvent.

[0087] The reservoir F is defined as the final reservoir for recovering the extract from the extraction process according to the invention.

[0088] The term "oilcake" means the solid residue of the extraction material from cashew nut shells, obtained at the outlet of the extractor chamber and which is depleted in solute after implementation of a process for extracting the solute from the extraction material.

[0089] In a counter-current extraction process, when the N extraction steps are indexed with an index i increasing according to the direction of introduction of the extraction material, it is understood that the miscella i of reservoir i is more enriched in solute than the miscella (i+1 ) of reservoir (i+1).

[0090] Advantageously in the solute extraction step b), each miscella i is filtered before their recovery in the reservoir i), in particular using a filter at the inlet of the reservoir.

[0091] Advantageously the recovery step c) includes a miscellas filtration step i.

[0092] Advantageously the recovery step c) further includes a step of concentrating the extract, in particular by a step of separating the solute and the solvent, in particular by evaporation of the solvent.

[0093] Advantageously, the process of the invention further includes steps of filtration, concentration or removal of the residual solvent from the extraction of the extract obtained in step c). Such steps and their implementation are known to a person skilled in the art.

[0094] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which said extraction is carried out by percolation or by immersion, preferably by percolation.

[0095] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which said extraction is carried out by per- snack.

[0096] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which said extraction is carried out by immersion.

[0097] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which the cashew nut shells are ground and are obtained in a preliminary step of grinding the cashew nut shells before step a).

[0098] Advantageously, the grinding step can be implemented at the inlet of the extraction chamber.

[0099] According to a particular embodiment, the present invention relates to an extraction process as defined above, further comprising a heat treatment step of cashew nut shells or crushed cashew nut shells before step a).

[0100] Advantageously, the heat treatment is carried out at a temperature above 140°C, preferably from 180 to 250°C or from 400 to 600°C, enabling the decarboxylation of anacardic acid to obtain an extract containing technical-grade CNSL. By way of non-limiting information, the heat treatment step can be carried out by roasting, for example, during the preparation process for separating the kernels from the shells of cashew nuts.

[0101] Advantageously, the heat treatment can be carried out under temperature or treatment time conditions allowing a composition to be achieved having a determined ratio of anacardic acid and cardanol.

[0102] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which steps a), b) and c) are carried out at a temperature of 20 to 140°C, in particular from 20 to 70°C, and / or at a pressure of 0.05 to 0.5 MPa, preferably about 0.1 MPa.

[0103] The expression MPa corresponds to 106 Pascals and is equivalent to 10 bars.

[0104] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which steps a), b) and c) are carried out at a temperature of 20 to 70°C and at a pressure of 0.05 to 0.5 MPa, preferably about 0.1 MPa.

[0105] The range of 20 to 140°C includes the following ranges: from 20 to 40°C, from 40 to 60°C, from 60 to 80°C, from 80 to 100°C, from 100 to 120°C, from 120 to 140°C.

[0106] The range of 20 to 70°C includes the following ranges: from 20 to 30°C, from 30 to 40°C, from 40 to 50°C, from 50 to 60°C, from 60 to 70°C.

[0107] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which steps a), b) and c) are carried out at a temperature of 20 to 140°C, in particular 20 to 70°C and at a pressure of 0.05 to 0.5 MPa, preferably about 0.1 MPa.

[0108] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which step b) comprises N extraction steps, N ranging from 3 to 10, preferably 3, 4, 5 or 6.

[0109] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which the solvent is chosen from ethyl acetate, butyl acetate, hexane, cyclohexane, 2-methyltetrahydrofuran, methanol and ethanol.

[0110] Ethyl acetate has the advantage of being a solvent that is not hazardous to humans. It does not belong to the class of CMR substances (Carcinogenic, Mutagenic, and Reprotoxic) and is classified as class 3 according to the ICH Q3C guideline. It is also not harmful to the environment. It is a solvent that can be obtained from bio-based sources. This solvent is selective for CNSL (traces of gallic acid).

[0111] Butyl acetate is a solvent that is not hazardous to humans (it does not belong to the class of CMR substances) or to the environment. It presents less risk of flammability than ethyl acetate. This solvent is selective for CNSL (traces of gallic acid).

[0112] Methanol has the advantage of being a solvent commonly used in industry. It is characterized by a low boiling point of approximately 65°C, which allows for the use of less energy-intensive removal processes. This solvent makes it possible to obtain an extract containing CNSL and tannins from cashew nut shells.

[0113] Ethanol has the advantage of being a bio-based solvent commonly used in industry. It presents less risk to humans than methanol (a class 3 solvent according to ICH Q3C). This solvent makes it possible to obtain an extract containing CNSL and tannins from cashew nut shells.

[0114] Hexane has the advantage of being commonly used in industry. It is characterized by a low boiling point of approximately 69°C, which allows for the use of less energy-intensive removal processes. This solvent is highly selective for CNSL (no trace of tannin).

[0115] Cyclohexane has the advantage of being a less dangerous alternative to hexane. This solvent is highly selective for CNSL (no tannin).

[0116] 2-Methyltetrahydrofuran has the advantage of being a bio-based solvent that does not belong to the class of CMR substances. This solvent is selective for CNSL (traces of tannins).

[0117] [Tables] Solvent Teb«0>5 ra Ethyl acetate 77 n-Butyl acetate 126 Hexane 69 Cyclohexane 81 2-Methyltetrahydrofuran 78-80 Methanol 65 Ethanol 79

[0118] Table 1: Boiling point of extraction solvents

[0119] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which:

[0120] - the solvent used is methanol or ethanol and leads to an extract comprising CNSL and tannins derived from cashew nut shells,

[0121] - and said process includes an additional separation step d) in which said extract comprising CNSL and tannins is separated into a CNSL oil and a residue containing said tannins.

[0122] In this embodiment, the use of methanol or ethanol as the extraction solvent allows for the extraction, as a solute, of CNSL compounds, as well as other compounds such as tannins from cashew nut shells. The extract obtained comprises the CNSL compounds and tannins from cashew nut shells.

[0123] Advantageously, said additional separation step d) is carried out by a selective solubilization step of the extract in an alkane-type solvent (preferably hexane and cyclohexane). This solvent is miscible with CNSL, whereas tannins are not soluble in this solvent.

[0124] Step d) can be carried out by other separation methods known to those skilled in the art.

[0125] By way of non-limiting examples, the separation step d) can be carried out by: - ​​the use of a clarifying agent such as gelatin, polyethylene glycol (PEG) or polyvinylpolypyrrolidone (PVPP), - or silica column separation - or micro / ultrafiltration

[0126] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which:

[0127] - the solvent used is ethyl acetate, butyl acetate, hexane, cyclohexane or 2-methyltetrahydrofuran and leads to an extract consisting of substantially pure CNSL,

[0128] - and said process includes an additional step of extraction e) of the press cake obtained in step c) by a solvent chosen from ethanol or methanol to obtain a solution containing tannins.

[0129] In this embodiment, the use of ethyl acetate, butyl acetate, hexane, cyclohexane, or 2-methyltetrahydrofuran, particularly hexane, as an extraction solvent allows for the extraction of only the CNSL compounds as solutes. The tannins are not solubilized in the porous system medium. The resulting extract comprises substantially only the CNSL compounds. Trace amounts of tannins of less than 1% may nevertheless be present, for example, when using ethyl acetate.

[0130] The tannins contained in the press cake are then extracted with an extraction step e).

[0131] Advantageously, said extraction step e) of the cake is carried out by percolation or immersion in methanol or ethanol by a similar process comprising similar steps a), b) and c) applied to the cake as extraction material.

[0132] Step e) can be carried out by other extraction methods known to those skilled in the art for extracting tannins such as maceration.

[0133] By way of non-limiting examples, step e) of the oilcake extraction can be carried out by: - extraction in a solvent such as methanol, ethanol, acetone, basic water, hot water (60 to 100°C) or a mixture of these solvents, - extraction by supercritical or ionic fluid, - or a solvent extraction assisted by microwaves or ultrasound.

[0134] According to a particular embodiment, the present invention relates to an extraction process as defined above, comprising an additional step of heat treatment of the extract to obtain a technical CNSL oil.

[0135] Advantageously the heat treatment is carried out at a temperature above 140°C, preferably from 140 to 250°C at atmospheric pressure of 0.1 MPa and results in the decarboxylation of anacardic acid into cardanol.

[0136] Advantageously the extract is pre-treated to remove residual solvent.

[0137] For information purposes:

[0138] - Decarboxylation temperature of anacardic acid: from 140°C to atmospheric pressure (in the presence of solvent). It is possible to "distill" anacardic acid under vacuum at high temperature (from 180°C), however part of the product may degrade by decarboxylation during the process.

[0139] - Boiling point of cardanol: between 180 and 200°C under vacuum (P < 5 mbars).

[0140] - Boiling temperature of cardol / methyl cardol: between 190 and 220°C (P < 5 mbars).

[0141] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which the crushed cashew nut shells have an average particle size of 1 mm to 1 cm, preferably 3 to 8 mm and / or a moisture content of 5 to 10%, in particular 6.0 to 6.5%.

[0142] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which the crushed cashew nut shells have an average particle size of 1 mm to 1 cm, preferably 3 to 8 mm.

[0143] The range from 1 mm to 1 cm includes the following ranges: from 1 to 2 mm; from 2 to 3 mm; from 3 to 4 mm; from 4 to 5 mm; from 5 to 6 mm; from 6 to 7 mm; from 7 to 8 mm; from 8 to 9 mm; from 9 mm to 1 cm.

[0144] The range from 3 mm to 8 mm includes the following ranges: from 3.00 to 3.5 mm; from 3.5 to 4.00 mm; from 4.00 to 4.5 mm; from 4.5 to 5.00 mm; from 5.00 to 5.50 mm; from 5.50 to 6.00 mm; from 6.00 to 6.50 mm; from 6.50 to 7.00 mm; from 7.00 to 7.50 mm; from 7.50 to 8.00 mm.

[0145] It is understood that the variability in size of ground cashew nut shells and their residues generates a complex porous system that influences liquid / solid extraction. Advantageously, the shells are ground to achieve an average particle size of 1 mm to 1 cm, allowing for a porosity and tortuous solvent displacement pattern during percolation that are optimized for the dissolution kinetics of the CNSL compounds.

[0146] A small particle size, on the order of 1 mm to 1 cm, will allow an increase in the contact surface with the solvent, promoting the extraction yield.

[0147] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which the cashew nut shells have a moisture content of 5 to 10%, in particular 6.0 to 6.5%.

[0148] The 5 to 10% range includes the following ranges: 5.0 to 5.5%; 5.5 to 6.0%; 6.0 to 6.5%; 6.5 to 7.0%; 7.0 to 7.5%; 7.5 to 8.0%; 8.0 to 8.5%; 8.5 to 9.0%; 9.0 to 9.5%; 9.5 to 10.0%.

[0149] The range from 6.00 to 6.50% includes the following ranges: from 6.00 to 6.10%; from 6.10 to 6.20%; from 6.20 to 6.30%; from 6.30 to 6.40%; from 6.40 to 6.50%.

[0150] The moisture content of the solid-phase extraction material can influence the state of the porous system and its affinity for the solvent during extraction.

[0151] It has been shown that pre-drying cashew nut shells to reduce their moisture content has little impact on CNSL extraction yield.

[0152] Advantageously, the process according to the invention does not require a drying step of the cashew nut shells constituting the extraction material before entering the extractor.

[0153] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which the porous system has an interstitial volume of 15 to 60% and / or a density of 0.9 to 1.6.

[0154] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which the porous system has an interstitial volume of 15 to 60%.

[0155] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which the porous system has a density of 0.9 to 1.6.

[0156] The range of 15 to 60% includes the following ranges: 15 to 20%, 20 to 30%, 30 to 40%, 40 to 50%, 50 to 60%.

[0157] The range from 0.9 to 1.6 includes the following ranges: from 0.9 to 1.0; from 1.0 to 1.1; from 1.1 to 1.2; from 1.2 to 1.3; from 1.3 to 1.4; from 1.5 to 1.6.

[0158] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which, during extraction, the ratios of material extracted to solvent are from 1:1 to 1:10 by volume, in particular from 1:1 to 1:2 by volume

[0159] The range 1:10 to 1:10 includes the ranges from 1:1 to 1:2; from 1:2 to 1:3; from 1:3 to 1:4; from 1:4 to 1:5; from 1:5 to 1:6; from 1:6 to 1:7; from 1:7 to 1:8; from 1:8 to 1:9; from 1:9 to 1:10.

[0160] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which in step a) the retention time in the extractor of the extraction material, defined as the duration of time separating the entry into the extractor of a fraction of the extraction material and the exit from the extractor of said same fraction of the extraction material, is from 40 minutes to 6 hours.

[0161] At the outlet of the extractor the extraction material, having undergone at least one CNSL extraction step, is depleted in CNSL compared to the extraction material entering the reactor.

[0162] The range from 40 minutes to 6 hours includes the following ranges: from 40 min to 1h; from 1h to 2h; from 2h to 3h; from 3h to 4h; from 4h to 6h.

[0163] The term “retention time” means the duration of time elapsed between the entry of a fraction of the extraction material into the extractor and the exit of said fraction of the extraction material from the extractor.

[0164] Advantageously, the speed of movement of the extraction material in the extractor is constant, allowing constant movement in the extractor and limiting clogging phenomena.

[0165] Advantageously, the movement of the extraction material can also be adapted sequentially in time in the extractor, so that a fraction of the extraction material i in a stage i of the extractor is not in motion during the extraction step i.

[0166] Advantageously, the retention time of the extraction material in each stage i of the extractor is from 20 min to 3 hours, in particular from 1 hour to 2 hours, preferably about 2 hours.

[0167] It has been observed, in the case of the system of ground cashew nut shells, in a continuous percolated process with three different solvents, namely with hexane, methanol and ethyl acetate, that after less than two hours of extraction, a plateau of maximum extraction yield in solute is reached for the three solvents.

[0168] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which in step a) the mass flow rate in the extractor of the extraction material is from 0.5 to 5000 kg / h, in particular from 0.5 to 5 kg / h (for example for a pilot extractor) or from 1000 to 5000 kg / h (for example for an industrial extractor), preferably from 1 to 2.5 kg / h or from 1600 to 3200 kg / h.

[0169] According to a particular embodiment in a pilot extractor, the present invention relates to an extraction process as defined above, in which in step a) the mass flow rate in the extractor of the extraction material is from 0.5 to 5 kg / h, in particular from 1 to 2.5 kg / h.

[0170] The range of 0.5 to 5 kg / h includes the following ranges: from 0.5 to 1 kg / h, from 1 to 1.5 kg / h; from 1.5 to 2 kg / h; from 2 to 2.5 kg / h; from 2.5 to 3 kg / h; from 3 to 3.5 kg / h; from 3.5 to 4 kg / h; from 4 to 4.5 kg / h; from 4.5 to 5 kg / h.

[0171] The range of 1 to 2.5 kg / h includes the following ranges: from 1 to 1.25 kg / h; from 1.25 to 1.50 kg / h; from 1.50 to 1.75 kg / h; from 1.75 to 2 kg / h; from 2 to 2.25 kg / h; from 2.25 to 2.50 kg / h.

[0172] Advantageously the process according to the invention as defined above is implemented to continuously produce 0.3 to 0.8 kg / h of extract containing or consisting of CNSL, possibly tannins.

[0173] The range of 0.3 to 0.8 kg / h includes the following ranges: from 0.3 to 0.4 kg / h; from 0.4 to 0.5 kg / h; from 0.5 to 0.6 kg / h; from 0.6 to 0.7 kg / h; from 0.7 to 0.8 kg / h.

[0174] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which in step a) the mass flow rate in the industrial-scale extractor of the extraction material is 1,000 to 5,000 kg / h, in particular 1,600 to 3,200 kg / h.

[0175] The range from 1,000 to 5,000 kg / h includes the following ranges: from 1,000 to 1,500 kg / h; from 1,500 to 2,000 kg / h; from 2,000 to 2,500 kg / h; from 2,500 to 3,000 kg / h; from 3,000 to 3,500 kg / h; from 3,500 to 4,000 kg / h; from 4,000 to 4,500 kg / h; from 4,500 to 5,000 kg / h.

[0176] The range from 1,600 to 3,200 kg / h includes the following ranges: from 1,600 to 2,000 kg / h; from 2,000 to 2,400 kg / h; from 2,400 to 2,800 kg / h; from 2,800 to 3,200 kg / h.

[0177] It is understood that the process according to the invention has the advantage of allowing continuous industrial quantities not accessible by traditional batch extraction methods.

[0178] With an estimated yield of 30%, the process according to the invention with a throughput of 2,400 kg / h would make it possible to produce approximately 720 kg of extract per hour continuously.

[0179] Advantageously the process according to the invention as defined above is implemented to continuously produce 480 to 960 kg / h of extract containing or consisting of CNSL, possibly tannins.

[0180] The range from 480 to 960 kg / h includes the following ranges: from 480 to 600 kg / h; from 600 to 720 kg / h; from 720 to 840 kg / h; from 840 to 960 kg / h.

[0181] It is also understood that the duration of the process can be adapted to the quantity of cashew nut shells to be treated or adapted to the volume of the extraction solvent and vice versa, unlike the implementation of a batch solvent extraction process.

[0182] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which in step b) at each of the N extraction steps, said miscella i recovered in a reservoir i is recirculated as a solvent to percolate the extraction material, giving a solute-enriched miscella in said reservoir i, said recirculation taking place in particular by means of a pump i.

[0183] Recirculating miscella i in stage i allows for optimization of solvent use.

[0184] Advantageously, in one embodiment, the recirculation flow rate of the miscella i is calculated according to the configuration of the extractor and in particular the configuration of the reservoir i so that the miscella i put back into circulation from the pump remains in its reservoir i.

[0185] The recirculation flow rate of miscella i can also be calculated according to the configuration of the extractor and in particular the configuration of the reservoir i so that the miscella i overflows from the reservoir i in order to recover the miscella i towards the neighboring reservoir (i-1) or towards a final extract recovery reservoir.

[0186] In a countercurrent extraction process, when the N extraction steps are indexed with an index i increasing according to the direction of introduction of the extraction material, it is understood that the reservoir (i-1) is that corresponding to the stage (i-1) which is intended to be used to extract an extraction material comprising more solute than the extraction material present at stage i. When i=l, the reservoir having an index 0 corresponds to the reservoir F for recovering the final extract.

[0187] According to a particular embodiment, the present invention relates to a process as defined above, in which the flow rate of the extraction solvent is modulated over time so that - in extraction step b), the recovered miscella i does not overflow from reservoir i, then - in the recovery step c), after the extraction step i when the miscella i is more concentrated in solute, the recirculation flow rate is increased by the pump i so that the miscella i overflows from the tank i to the neighboring tank (i-1) or to a tank F for the recovery of the final extract.

[0188] According to a particular embodiment, the present invention relates to an extraction process as defined above, in which in step c), each reservoir i is positioned to overflow onto the reservoir i-1, when i = 1, the reservoir i-1 corresponding to the reservoir F.

[0189] The term “reservoir F” means the final recovery reservoir of the extract obtained by the extraction process according to the invention.

[0190] It is understood that the sum of successive overflows from a reservoir i to a neighboring reservoir (i-1) can be controlled or programmed to optimize the counter-current extraction process, for example by controlling the flow rate of the solvent or by influencing the configuration of the reservoirs.

[0191] Another object of the present invention relates to a porous system comprising the shells, in particular ground, of cashew nuts and the solvent, which can be obtained by the process according to the invention as defined above.

[0192] The porous system of the invention is a state obtained during the extraction process. The characteristics of the porous system are defined during the solvent extraction step, i.e. in the case of percolation extraction when the solvent passes through the extraction material.

[0193] Another object of the present invention relates to an extract containing or consisting of cashew nut shell oil, which can be obtained by the process as defined above.

[0194] According to a particular embodiment, the present invention relates to an extract as defined above containing or consisting of a natural CNSL oil, which can be obtained by the process as defined above.

[0195] According to a particular embodiment, the present invention relates to an extract as defined above containing or consisting of: - 60 to 80% by weight of anacardic acid, - 3 to 15% by weight of cardanol, - from 15 to 25% by weight of cardol and methyl cardol,

[0196] capable of being obtained by the process as defined above.

[0197] According to a particular embodiment, the present invention relates to an extract such as defined above containing or consisting of natural CNSL oil and tannins, capable of being obtained by the process as defined above.

[0198] According to a particular embodiment, the present invention relates to an extract as defined above containing or consisting of: - 60 to 80% by weight of anacardic acid, - 2 to 15% by weight of cardanol, - from 15 to 25% by weight of cardol and methyl cardol, - 0 to 15% by weight of tannins,

[0199] capable of being obtained by the process as defined above.

[0200] According to a particular embodiment, the present invention relates to an extract as defined above containing or consisting of a technical CNSL oil, which can be obtained by the process as defined above.

[0201] According to a particular embodiment, the present invention relates to an extract as defined above containing or consisting of: - less than 5% by weight of anacardic acid, - 60 to 80% by weight of cardanol, - from 15 to 30% by weight of cardol and methyl cardol,

[0202] capable of being obtained by the process as defined above.

[0203] According to a particular embodiment, the present invention relates to an extract as defined above containing or consisting of a technical CNSL oil and tannins, which can be obtained by the process as defined above.

[0204] According to a particular embodiment, the present invention relates to an extract as defined above containing or consisting of: - less than 5% by weight of anacardic acid, - 60 to 80% by weight of cardanol, - from 15 to 30% by weight of cardol and methyl cardol, - 0 to 15% by weight of tannins,

[0205] capable of being obtained by the process as defined above.

[0206] Another object of the present invention relates to a natural or technical CNSL oil from cashew nut shells, which can be obtained by the process as defined above.

[0207] According to a particular embodiment, the present invention relates to a natural CNSL oil from cashew nut shells as defined above containing or composed of: - 60 to 80% by weight of anacardic acid, - 3 to 15% by weight of cardanol, - from 15 to 25% by weight of cardol and methyl cardol,

[0208] capable of being obtained by the process as defined above.

[0209] According to a particular embodiment, the present invention relates to a technical cashew nut shell oil as defined above containing or composed of: less than 5% by weight of anacardic acid, 60 to 80% by weight of cardanol, from 15 to 30% by weight of cardol and methyl cardol, from 0 to 15% by weight of tannins,

[0210] capable of being obtained by the process as defined above.

[0211] Another object of the present invention relates to a cashew nut shell cake that can be obtained by the process as defined above.

[0212] The cashew nut shell cake obtained at the end of the process according to the invention as defined above comprises less than 5%, preferably less than 1% of CNSL and can be valorized.

[0213] By way of non-limiting example, the oilcake obtained according to the process of the invention can be used in a gasification process consisting of converting biomass into gas. It can also be converted into combustible briquettes serving as a solid fuel substitute for coal and firewood for domestic cooking. The degradation of the oilcake can be accelerated by bioactivation and thus used in composting.

[0214] The press cake exits the extractor continuously and can be easily recovered, processed or shaped.

[0215] Another object of the present invention relates to a composition of tannins derived from cashew nut shells that can be obtained by the process as defined above.

[0216] Tannins are as defined above.

[0217] It should be noted that the process described in the invention makes it possible to obtain a natural CNSL, in which the main phenolic compounds (anacardic acid, cardanol, cardol) have not been thermally degraded.

[0218] The [Fig. [1] represents an embodiment of the percolation process of the invention implemented in a four-stage, counter-current, continuous solid-liquid extraction plant comprising an inlet end (1), an outlet end (2), a gun (3) comprising a single screw (5) arranged horizontally above a series of four retention tanks (41, 42, 43, 44) R1, R2, R3, and R4 aligned from the inlet end of the extraction material from the reactor along the longitudinal axis of the screw with an inclination (10), nozzles (6) at each stage for percolating the extraction material, a solvent supply system (7) comprising a solvent inlet pipe (71) located at the outlet end and comprising, at each stage i, a pump i (8) connected to a tank i (41, 42, 43, 44), and filtration means. (9) present in the barrel and / or at the inlet of the tanks, a recovery F (45) tank connected to the RI tank.

[0219] Fig. 2 represents the yields obtained in extract with the three techniques implemented, respectively with a Soxhlet extraction, a one-stage extraction by maceration or "leaching" and a continuous extraction by percolation, carried out with two different solvents, hexane and methanol.

[0220] Fig. 3 represents the extract yields for continuous percolation extraction as a function of the extraction time for 3 different extraction solvents, hexane, methanol and ethyl acetate.

[0221] We will now describe, in a non-limiting manner, with reference to [Fig.1], an embodiment of the process implemented by a continuous counter-current Solid-Liquid extraction installation.

[0222] Description of an installation (pilot)

[0223] The extractor below is described for 4 stages, i.e. N equal to 4, but it is understood that it can be adapted for N equal to 3 to 10 stages, in particular from 4 to 6 stages.

[0224] The 4-stage extractor comprises an enclosure including:

[0225] - an inlet end (1) connected to a hopper (11),

[0226] - an output end (2),

[0227] - a barrel (3) comprising a single screw (5) arranged horizontally above of a series of 4 retention tanks RI, R2, R3 and R4 aligned (41, 42, 43, 44) from the inlet end (1) of the reactor extraction material along the longitudinal axis of the screw,

[0228] - nozzles (6) at each stage to percolate the extraction material,

[0229] - a solvent supply system (7) comprising a solvent inlet pipe ( 71) located at the outlet end and at each stage i, a pump i (8) connected to a reservoir i,

[0230] - filtration means (9) present in the barrel and / or at the inlet of the tanks,

[0231] - a recovery tank F (45) connected to the RL tank

[0232] The screw conveyor has a diameter of 50 to 500 mm, preferably 80 to 120 mm. The screw (5) is configured to rotate continuously in one direction. A hopper (11) is positioned to feed the beginning of the screw conveyor at the inlet of the reactor vessel.

[0233] The tanks (41, 42, 43, 44) are positioned side by side and advantageously equipped with a filtration means (9), such as a filter, for example, a filter cloth. These tanks (41, 42, 43, 44) are placed on an inclined plane (10) relative to the horizontal plane and are configured so that tank R1 can overflow, feeding the adjacent tank R4, for example, tank R4 (44) can The extractor overflows by feeding reservoir R3 (43), allowing R3 to overflow onto R2 (42), R2 onto RI (41), and RI into a reservoir F (45) for extract recovery. The extractor is segmented into 4 stages, each corresponding to a reservoir.

[0234] In the extractor, during operation, contact between the solvent and the extraction material occurs by percolation using a nozzle (8). The direction of the solvent flow is opposite to that of the introduction of the crushed cashew nut shells. The freshly introduced solvent is in contact with the solute-depleted material, while the fresh material is in contact with the solute-enriched solvent. Each reservoir is connected to a pump (8) and a dispersing nozzle (6) which ensures the recirculation of the solvent within said reservoir i.

[0235] Advantageously temperature sensors and plate heat exchangers are regularly distributed along the extractor.

[0236] The extractor can be chosen from among the extractors of the Vatron-Mau company.

[0237] Description of an embodiment

[0238] In one embodiment of the process, pre-ground cashew nut shells with a particle size of 1 mm to 1 cm, preferably 3 and 8 mm, are introduced into a hopper of the continuous extraction reactor at the inlet end (1).

[0239] All the operations described below are carried out at a temperature of 20 to 80°C, preferably 50 to 70°C and at atmospheric pressure.

[0240] At startup, before the extraction steps, the tanks (41, 42, 43, 44) are filled with solvent. Fresh solvent is introduced through a pipe (71) located at the outlet end of the reactor directly into tank R4 (44). Solvent is added until tank RI (41) is filled to its maximum capacity, by means of an overflow system, with tank RI (41) not overflowing into tank F (45) intended for extract recovery.

[0241] The auger (5) is started, then once the desired rotation speed is reached, the hopper valve (11) containing the crushed cashew nut shells is opened, and the hopper is then continuously fed with the crushed cashew nut shells.

[0242] The ground cashew nut shells are introduced into the inlet end (1) of the reactor vessel into the barrel (3) and conveyed to the other outlet end (2) of the reactor vessel by rotation of the screw (5). The retention or residence time in the reactor varies from 40 min to 6 h, depending in particular on the rotation speed of the screw.

[0243] At the nominal operating point, the mass flow rate of crushed cashew nut shells is 1 kg.h'.

[0244] When the screw assembly (5) is loaded with the crushed shells, the extraction step at each stage of the extractor begins.

[0245] Extraction step on floor i

[0246] For each stage i, a withdrawal valve, positioned at the bottom of each tank i (41, 42, 43, 44), is opened. This allows the recirculation pump i (8) attached to this tank to be supplied via a pipe. At the same time, the recirculation pump (8) is started operating at a flow rate calculated according to the tank volume, allowing the solvent to be recirculated within the same tank, advantageously at 1 m³ / h for a 30L tank.

[0247] The solvent is dispersed by the corresponding nozzle (6), which is configured to bring the solvent into contact with the extraction material by a percolation process. In particular, during percolation, a porous system is formed from the extraction material and the solvent.

[0248] Advantageously in this porous system, the exchange surface between the solvent and the extraction material allows the solvent to solubilize the solutes present in the extraction material, namely the CNSL compounds and possibly tannins.

[0249] The solvent and the solute form a miscella. The miscella (CNSL / solvent) is separated from the extraction material by filtration means (9) which may be present in the barrel and / or at the inlet of the tanks.

[0250] At the end of percolation and by gravity in stage i, the solvent is then recovered in reservoir i.

[0251] The filter cloth in the reservoir allows some solid particles to be retained which may be carried away by the solvent, while at the bottom of the reservoir, the liquid filtrate consists of the CNSL solute / solvent mixture.

[0252] In the reservoir i, the miscella will be transferred a second time, thanks to the recirculation pump (8) and the pipes, above the screw conveyor loaded with crushed cashew nut shells.

[0253] A second percolation of the extraction material by the miscella i is carried out and leads to the filling of the reservoir i by a miscella enriched in solute.

[0254] In the same way as before, the solid / liquid separation is ensured by the filter cloth within the reservoir i itself.

[0255] Transfer for the countercurrent process

[0256] The transfer of solvent from one reservoir to the other is carried out by overflow. Advantageously, the pump flow rate is then increased in order to cause the overflow from reservoir i to reservoir (i-1).

[0257] Thus the miscella from reservoir i is transferred into reservoir (i-1).

[0258] The recirculation of the solvent in the second reservoir (i-1) is started, two percolations are carried out with the solvent contained in the reservoir (i-1), and so on until the last reservoir RI (41).

[0259] The last RI tank overflows into a retention basin F (45).

[0260] Once all the solute-laden solvent has been recovered in the retention tank F(45), the contents of the tank are transferred to a distillation unit. The solvent is then distilled under reduced pressure and at a temperature of 20 to 60°C, preferably 50°C, to obtain the CNSL.

[0261] The solvent thus distilled can then be reintroduced into the continuous counter-current extraction process.

[0262] It is understood that the extraction steps i can be carried out concurrently.

[0263] Description of an industrial installation

[0264] The above pilot extractor is adaptable for an industrial installation of 6 to 10 floors. To increase the material throughput, the screw conveyor can be replaced by a material conveyor belt allowing a material throughput of approximately 1,600 to 3,200 kg / hour, corresponding to a CNSL volume estimated at 480 to 960 kg / h. The size of the tanks is adapted accordingly to the industrial scale, with the volume of a tank being, for example, 1.2 m³.

[0265] Example 1: Comparative study of solvent extraction techniques.

[0266] Three solvent extraction techniques applied to the extraction of CNSL from crushed cashew nut shells were studied and compared.

[0267] a) Soxhlet extraction

[0268] Solvent: Hexane

[0269] Cashew nut shells are supplied by Orpia Innovation. Hexane (VWR, technical grade) is used without prior purification. The experimental setup consists of a Soxhlet extractor (250 mL), a condenser, a round-bottom flask (250 mL), a heating mantle, a cellulose cartridge (33 x 100 mm), and cotton. The cashew nut shells are ground for 15 seconds using a Waring-type kitchen blender. The grinding results in a mixture of sticky brown paste and fine cashew nut shell residue.

[0270] 20g of cashew nut shells ground in a blender are introduced into the cartridge at The Soxhlet flask is then filled with cotton up to the surface of the cartridge. 200 mL of hexane is introduced into the flask, which has been pre-weighed to a 1:10 (w / v) ratio of cocci to solvent. Heating is initiated, and the extraction continues for 6 hours under reflux of hexane.

[0271] After extraction, the solvent in the flask is evaporated under reduced pressure at 50°C using a R-300 rotary evaporator connected to a Büchi V-600 pump. The resulting extract is then dried under vacuum at room temperature for 1.5 hours. A brown oil is obtained, with a mass of 6.78 g and a mass yield of 33.9%.

[0272] Solvent: Methanol

[0273] The same operating procedure was implemented with methanol as the solvent. In this case, a brown oil and a solid deposit were observed at the end of evaporation and the overall yield of the extract is higher (42.5%) than that with hexane as the solvent, this being due to the presence of tannins.

[0274] b) One-stage extraction: maceration

[0275] Solvent: Hexane

[0276] The cashew nut shells are supplied by Orpia Innovation. Hexane (VWR, technical grade) is used without prior purification. The experimental setup consists of a double-jacketed glass reactor, a magnetic stirrer, and a Huber brand cryo-thermostat (model: Ministat 125). The shells are ground for 15 seconds using a Waring-type kitchen blender. The grinding results in a mixture of sticky brown paste and fine shell residue.

[0277] 10g of crushed shells are introduced into the double-jacketed reactor, The mixture is supplemented with 100 mL of hexane to achieve a 1:10 (w / v) ratio of crushed shells to solvent. The temperature of the water circulating in the double wall is set to 55°C, and maceration continues for 6 hours. The suspension is then centrifuged (5000 g, 5 min, 20°C), the supernatant is collected, and then filtered under vacuum using a Büchner funnel. The shell residue is washed on the Büchner funnel with 2 x 15 mL of hexane. The solvent is then evaporated under reduced pressure at 50°C using a R-300 rotary evaporator connected to a Büchi V-600 pump. The resulting extract is then dried under vacuum at room temperature for 36 hours. A brown oil is obtained, with a mass of 2.85 g and a mass yield of 28.5%.

[0278] Solvent: Methanol

[0279] The same operating procedure was implemented with methanol as the solvent. In the case of methanol, a brown oil and a solid deposit are observed at the end of evaporation, and the overall mass yield of the extract is higher (36.4%) than that with hexane as the solvent, due to the presence of tannins.

[0280] c) Continuous extraction by percolation

[0281] Solvent: Hexane

[0282] Cashew nut shells are supplied by Orpia Innovation. Hexane (VWR, technical grade) is used without prior purification. The operating setup consists of an automatic Soxhlet extractor (Büchi B-811), a glass container (200 mL), a cellulose cartridge (33 x 100 mm), and cotton. The shells are ground for 15 seconds using a Waring-type kitchen blender. The grinding results in a mixture of sticky brown paste and fine shell residue.

[0283] 20g of crushed shells are introduced into the Soxhlet cartridge, this The last layer is filled with cotton up to the surface of the cartridge. 200 mL of hexane are introduced into the glass container at a shells / solvent ratio of 1:10 (w / v). The automatic Soxhlet extractor is set to "continuous extraction" mode, which allows for mimicking the conditions of the continuous extraction process (the solvent (condensate is not retained in the extraction chamber). The heater is switched on and the extraction continues for 6 hours with hexane reflux.

[0284] After extraction, the solvent is evaporated under reduced pressure at 50°C using a R-300 rotary evaporator connected to a Büchi V-600 pump. The resulting extract is then dried under vacuum at room temperature for 1.5 hours. This yields a brown oil, m = 6.25 g, with a mass yield of r = 31.2%.

[0285] Solvent: Methanol

[0286] The same operating procedure was implemented with methanol as the solvent. In the case of methanol, a brown oil and a solid deposit are observed at the end of evaporation, and the overall mass yield of the extract is higher (42.3%) than that with hexane as the solvent, this being due to the presence of tannins.

[0287] d) Comparison

[0288] Fig. 2 represents the yields obtained with the three techniques implemented with two different solvents.

[0289] The mass yields of the extract obtained are higher in methanol than in hexane in the 3 extraction processes analyzed, probably indicating the presence of tannins with the use of methanol.

[0290] The continuous percolation extraction process of example i) constitutes an alternative to conventional batch Soxhlet extraction in view of the observed yields. Furthermore, the continuous extraction process drastically reduces the extraction time.

[0291] The continuous extraction process by percolation makes it possible to reduce extraction times for very good and almost maximum yields.

[0292] In general, unlike a Soxhlet process, the continuous percolation process increases the exchange of matter between the solid and liquid phases, reduces the amount of extraction solvent and improves productivity.

[0293] Hexane as an extraction solvent makes it possible to obtain natural CNSL with a purity far superior to that obtained using methanol. Indeed, using hexane would not cause the tannins to dissolve in the extract. The presence of residual solvents (such as methanol) can be eliminated by techniques known to those skilled in the art.

[0294] Example 2: Kinetics: optimization time of continuous extraction by percolation.

[0295] The kinetics of continuous extraction was studied with a protocol similar to Example Le) for the 3 solvents (hexane, methanol and ethyl acetate) in which the reaction is stopped at different times t = 15 min, 30 min, 45 min, 60 min, 120 min and 180 min.

[0296] In a continuous extraction by percolation, [Fig.3] indicates that at t = 2h, the maximum mass yield of extract is reached for the 3 solvents.

[0297] Methanol has better mass yields in extract, but implies the presence of tannins in the extract.

[0298] Ethyl acetate, a bio-based solvent, allows for the recovery of more extract after the required 2 hours; however, its extraction kinetics are lower than those of hexane, a petroleum-based solvent. The trade-off of a slightly longer extraction time for more efficient and eco-friendly extraction is a criterion for choosing the extraction solvent.

[0299] Example 3: Separation of CNSL and tannins by selective solubilization in hexane.

[0300] Cashew nut shells are supplied by Orpia Innovation. Methanol and hexane (VWR, technical grade) are used without prior purification.

[0301] The operating setup consists of an automatic Soxhlet (Büchi B-811), a glass container (200 mL), a cellulose cartridge (33x100 mm, part number 900820, lot 1930), a 500 mL flask, and cotton. The cashew nut shells are finely ground using a Robot Coupe Blixer 2 food processor for 15 seconds, resulting in a mixture of sticky brown paste and fine shell residue.

[0302] The crushed shells (mc = 22.827 g) are introduced into the cartridge located in the extraction chamber, which is then filled with cotton to its surface. 200 mL of MeOH are introduced into the glass container at a shells / solvent ratio of 1:10 (w / v). The MeOH is heated to boiling, and the extraction continues for 6 hours under reflux. The mixture is transferred to the flask, and the solvent is then evaporated under reduced pressure at 50°C (rotary steamer). The product is then dried under vacuum at room temperature for 1.5 hours. An oily mixture with solid residues (tannins) is obtained, mp = 10.038 g (rSoxhiet = 44.0%).

[0303] The resulting oily mixture undergoes a hot resolubilization step in hexane. The apparatus consists of a 500 mL round-bottom flask, a heating mantle, a water-cooled condenser, and a magnetic stir bar. 110 mL of technical-grade hexane is introduced into the flask and brought to a boil with stirring (v = 800 rpm). After maceration for 1.5 hours, the mixture is hot-filtered under vacuum using a Buchner funnel with filter paper (porosity 4).

[0304] On the one hand, for the filtrate, the hexane is evaporated under reduced pressure at 50°C (rotary steamer) and then the product is dried under vacuum at room temperature for 2 hours. Obtaining a single-phase filtrate of CNSL, mCNSL = 7.066 g, rCNSL = 31.0%.

[0305] On the other hand, for the solid residue, the filter + filter paper assembly is washed by 2x15 mL of MeOH is reintroduced into the flask that underwent resolubilization and contains traces of hexane-insoluble solids. The MeOH is then evaporated under reduced pressure at 50°C (rotary steamer), and the product is dried under vacuum at room temperature for 2 hours. A dark solid residue is obtained, with mtanins = 2.289 g and rtanins = 10.03%.

[0306] It should be noted that some product losses are observed during the resolubilization step since the 44% yield of the CNSL / tannin mixture is not recovered.

Claims

Demands

1. Use, for the implementation of a solvent extraction process of an extract containing or consisting of a natural or technical CNSL oil and optionally tannins from cashew nut shells, in particular ground, of a continuous introduction into an extractor of cashew nut shells, in particular ground, constituting the extraction material, causing the passage of said extraction material from the inlet of the extractor chamber to the outlet of said extractor chamber, said introduction being carried out counter-current to the direction of the flow of said solvent, said extraction material forming with the solvent a porous system, and in which the extraction process is carried out in an extractor comprising several stages, and at a pressure of 0.05 to 0.5 MPa.

2. Use according to claim 1, wherein the extraction process is carried out by percolation of the solvent through the extraction material or by immersion of the extraction material in the solvent.

3. Use according to any one of claims 1 or 2, wherein the extraction process is carried out in an extractor comprising 3 to 10 stages.

4. A process for preparing an extract containing or consisting of a natural or technical CNSL oil and optionally tannins by solvent extraction from cashew nut shells, in particular ground, comprising the following steps: a) a step of continuously introducing cashew nut shells, in particular ground, constituting the extraction material, into an extractor, causing said extraction material to flow from the inlet of the extractor chamber to the outlet of said extractor chamber; b) a solute extraction step comprising N solvent extraction step(s) during the passage of said extraction material through the extractor, N ranging from 2 to 10, said extraction material and the solvent forming a porous system, wherein the direction of said introduction is countercurrent to that of the solvent flow, wherein for each extraction step i, i ranging from 1 to N, leads to obtaining an extracted liquid phase i containing a solute i and the solvent, said solute i forming with the solvent a miscella i, which miscella i is recovered in a reservoir i, c) a recovery step: - of each of the aforementioned miscella i, i varying from 1 to N, in a reservoir F to obtain said extract containing or consisting of the CNSL and possibly tannins and - possibly of the press cake, resulting from the extraction material after step b) of extraction of the solute, at the outlet of the extractor enclosure, in which steps a), b) and c) are carried out at a pressure of 0.05 to 0.5 MPa, preferably at 0.1 MPa.

5. A process according to claim 4, wherein the cashew nut shells are ground and are obtained in a preliminary step of grinding the cashew nut shells before step a), and / or further comprising a heat treatment step of the cashew nut shells or the ground cashew nut shells before step a), and / or wherein steps a), b) and c) are carried out at a temperature of 20 to 140°C, in particular 20 to 70°C, and / or at a pressure of about 0.1 MPa.

6. A method according to any one of claims 4 to 5, wherein the solvent is selected from ethyl acetate, butyl acetate, hexane, cyclohexane, 2-methyltetrahydrofuran, methanol and ethanol.

7. A process according to claim 6, wherein: - the solvent used is methanol or ethanol and leads to an extract comprising CNSL and tannins from cashew nut shells, - and said process comprises a further separation step d) in which said extract comprising CNSL and tannins is separated into a CNSL oil and a solid residue containing said tannins.

8. A process according to claim 6, wherein: - the solvent used is ethyl acetate, butyl acetate, hexane, cyclohexane or 2-methyltetrahydrofuran and leads to an extract consisting of substantially pure CNSL, - and said process comprises a further step of extraction e) of the cake obtained in step c) by a solvent selected from ethanol or methanol to obtain a solution containing tannins.

9. A process according to any one of claims 4 to 8, comprising an additional step of heat-treating the extract to obtain an oil CNSL technical.

10. A process according to any one of claims 4 to 9, wherein the cashew nut shells have an average particle size of 1 mm to 1 cm, and / or a moisture content of 5 to 10%, in particular 6.0 to 6.5%, and / or wherein the porous system has an interstitial volume of 15 to 60%, and / or a density of 0.9 to 1.6, and / or wherein during extraction the extraction material:solvent ratios of 1:1 to 1:10 by volume, in particular 1:1 to 1:

2.

11. A method according to any one of claims 4 to 10, wherein in step a) the retention time in the extractor of the extraction material, defined as the duration of time separating the entry into the extractor of a fraction of the extraction material and the exit from the extractor of said same fraction of the extraction material, is 40 min to 6 h, and / or wherein in step a) the mass flow rate in the extractor of the extraction material is 0.5 to 5000 kg / h, in particular 0.5 to 5 kg / h or 1000 to 5000 kg / h.

12. A method according to any one of claims 4 to 11, wherein - in step b) at each of the N extraction steps, said miscella i recovered in a reservoir i is recirculated as a solvent to percolate the extraction material, giving a solute-enriched miscella i in said same reservoir i, said recirculation taking place in particular by means of a pump i, and / or wherein, in step c), each tank i is positioned to overflow onto tank i -1, when i = 1, tank i -1 corresponding to tank F.

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