FR2873129A1 - Extraction of oil from oleaginous/high-protein seeds, useful as animal fodder, comprises grinding and cold pressing of seeds to obtain fatty oil cake, washing the cake to recuperate residue, fractionating, and treating the residues - Google Patents

Abstract

Extraction of oil from oleaginous or high-protein seeds (I) comprising: (a) grinding and cold pressing of the seeds to obtain a fatty oil cake (II); washing (II) to recuperate a first solid residue (A); (b) first fractionation of to separate a water with mucilage concentration and a second solid residue (B); second fractionation of to separate an emulsion concentrated in proteins and a third solid residue (C); and (c) treatment of (C), is new. Extraction of oil from oleaginous or high-protein seeds (I) comprises: grinding and cold pressing of (I) to obtain a fatty oil cake (II); washing (II) to recuperate a first solid residue (A); fractionation of (A) to separate water with mucilage concentration and a second solid residue (B); fractionation of (B) to separate an emulsion concentrated in proteins and a third solid residue (C); and treatment of (C) (where the first and second fractionation comprises a treatment phase by high voltage electrical discharge).

Description

Process for extracting oil from oleaginous seeds or

  protein crops, including high voltage electrical discharge treatment.

  The field of the invention is that of industrial processes for extracting oil contained in a material. More specifically, the invention relates to a process for extracting oil contained in oleaginous or proteinaceous seeds.

  In the field of the invention, the oil extraction methods of the oilseeds are of the type illustrated diagrammatically in FIG.

  Such a method is more particularly used for the mechanical extraction (by pressing) of the oil as it is performed on flax (steps 100 to 104).

  For this seed, two ways are possible after crushing the seeds (step 100): a simple cold pressing (step 101), after which the extracted oil undergoes a filtration step (step 102); a double pressing, first cold (step 101), then hot (step 104), a cooking step (step 103) generally occurring between the two pressing.

  Due to the special qualities of oilseed oil, the current industry stops at the hot pressing stage, the fat cakes from this stage being marketed in the state (or almost) for animal feed .

  In some cases, the fat cakes from the hot pressing step are processed by solvent extraction units.

  The fatty cake then undergoes a step of extraction using a solvent (generally hexane) after which one recovers on the one hand a miscella which is subjected to a distillation step (106) and, on the other hand, deoiled cakes which are subjected to a toasting step (107), the deoiled and desolvated cakes from step 107 being intended for animal feed.

  In view of a genetic modification of flaxseed to produce saturated and branched fatty acids, the direct valuation of fatcake becomes very improbable. Profitability or the industry then requires extracting the oil present in the oilcake and enhance co-products such as proteins.

  This recovery requires the elimination of the hot steps of the traditional process, such as cooking, hot pressing or toasting.

  In addition, in a concern for sustainable development, the use of conventional solvent extraction is not a way forward.

  Indeed, the technique of solvent extraction of the residual oil of a cake leads to a loss of solvent of 3 to 4 liters per ton of treated product.

  Due to current environmental considerations, such a loss is obviously not acceptable.

  The object of the invention is in particular to overcome the drawbacks of the prior art.

  More specifically, the object of the invention is to propose a process for extracting oil from oleaginous or proteinaceous seeds, which makes it possible to avoid the use of a solvent that is harmful to the environment such as those used in the conventional processes of the invention. prior art.

  The invention also aims to provide such a process that allows both the extraction of oil and recovery co-products.

  The purpose of the invention is also to provide such a method which makes it possible to envisage an increase in the extraction kinematics of the compounds contained in the seeds.

  Another object of the invention is to provide such a method that allows to consider energy savings compared to the methods of the prior art.

  These objectives, as well as others which will appear later, are achieved by the invention which aims at a method of extracting oil from oleaginous or proteinaceous seeds, comprising a grinding step and a step cold pressing, after which a fat meal is obtained, characterized in that it comprises: a grinding step followed by a step of washing said fatty cake in order to recover a first solid residue; a first step of fractioning said first solid residue to separate concentrated water into mucilage and a second solid residue; a second step of fractionating said second solid residue to separate a protein concentrated emulsion and a third solid residue; a step of treating said third solid residue to extract oil therefrom, said first and second fractionation steps including a high voltage electrical discharge treatment phase.

  In the field of the invention, the mechanisms for extracting oils and proteins from oleaginous or oleo-proteinaceous seeds are still poorly known because of the complexity of the plant raw material. The classic problem in process engineering is the provision of molecules of interest inside the cell matrix and their expulsion using either pressure gradients (pressure filtration) or concentration gradients. (extraction).

  Temperature plays an important role in improving transfer kinetics (decrease in viscosity and increase of diffusion coefficients).

  The baking aspect is also essential because the coagulation of the proteins inside the plant tissues makes it possible to break up the lipid globules and makes the oil available for its extraction. Finally, water also plays a major role although poorly defined: there is usually an optimum water content to facilitate extraction.

  The method according to the invention proposes a break with the preceding methods.

  In fact, if a cold pressing part is kept for economic reasons (the pressure is a mechanical operation that consumes little energy and makes it possible to obtain a first cold-pressed oil of excellent quality), the process according to US Pat. The invention aims to solubilize or emulsify the cellular content by permeabilizing the tissues and causing intense agitation at the microscopic scale.

  A cellular juice is thus obtained which must then be cracked to separate water, oil and soluble substances such as proteins and carbohydrates (including mucilages).

  In other words, all the effects created by the high-voltage electrical discharge treatment phases cause fine particle disaggregation and the activation of mass transfers, which makes it possible to extract biological compounds.

  It should be noted that the process according to the invention makes no use of solvents which are harmful to the environment, such as those used in conventional solvent extraction processes.

  Beyond the environmental and energetic aspects, another advantage of the process according to the invention resides in its robustness with respect to the quality of the treated raw material (oil content, water content, particle size, initial temperature ). While the above-mentioned parameters strongly influence the performance of pressing and solvent extraction processes, the method described based on the application of electrical discharges in an aqueous phase makes it possible to grind and homogenize the treated material.

  An important aspect of the technique according to the invention lies in the creation of an electric arc in the water during the fractionation phases. The very fast energy release of an electrical capacitor creates high pressures and high temperatures in the plasma discharge channel.

  The rapid expansion of the plasma channels, the local temperature gradients and the non-elastic properties of the liquid which cause the formation of shock waves, produce optimized results with respect to the successive splits of the treated material.

  According to a preferred solution, said step of treating said third solid residue comprises an enzymatic digestion phase.

  In this case, said enzymatic digestion phase is preferably followed by an emulsification of said third digested residue and then of a membrane separation phase at the end of which said oil is extracted.

  In this way, the rate of oil extraction contained in the treated solid residue is increased.

  According to an advantageous solution, the method comprises a centrifugal flotation step of a mucilage-poor emulsion recovered at the end of said washing step.

  This optimizes the recovery of one of the compounds of the treated raw material.

  Preferably, the method comprises a membrane separation step of said protein-loaded emulsion.

  In this way, the extraction rate of the oil contained in the treated raw material can be further increased.

  According to a preferred embodiment, said first and second residues are dissolved with water in a water / cake ratio of 10/1 by weight.

  Such a ratio tends to optimize the action of electric discharges, while limiting the quantities of water used.

  Advantageously, the process comprises a step of suspending said first residue and / or said second residue in an emulsion intended to undergo a centrifugation step.

  According to an advantageous solution, said electric discharges have a voltage of between approximately 30 kV and 50 kV.

  Preferably, said electric discharges have a voltage of approximately 40 kV.

  Preferably, said electric discharges are produced at a frequency of approximately 0.5 Hz to 10 Hz.

  Other characteristics and advantages of the invention will emerge more clearly on reading the following description of a preferred embodiment of the invention, given by way of illustrative and nonlimiting example, and the appended drawings among which: FIG. 1 illustrates in the form of a diagram a process for extracting oil from oleaginous seeds according to the prior art; FIG. 2 illustrates in the form of a diagram a preferred embodiment of a process for extracting oil from oleaginous seeds according to the invention; Fig. 3 is an example of recording the voltage and the intensity of electric discharges produced during the process according to the invention; Figure 4 is a schematic view of a processing chamber for carrying out the method according to the invention.

  With reference to FIG. 2, according to one embodiment of the invention, the oleaginous seeds undergo a milling step 20 and a cold pressing step 21 known per se, after which one recovers, on the one hand, the oil to be filtered in a step 22 and, on the other hand, a fat cake.

  According to a first phase of the process according to the invention, the fatcakes recovered after cold pressing are crushed (step 23) and then washed (step 24), after which a solid residue and an emulsion without mucilage (or poor in mucilage) are recovered. ) which is subjected to centrifugal flotation (step 240) to extract the oil.

  According to a second phase of the process according to the invention, the solid residue resulting from the washing step 24 undergoes a first fractionation step.

  According to the present embodiment, the solid residue is placed in solution with water in a weight ratio water / cake of 10 to 1 (for example), this solution being introduced into a treatment chamber (explained in more detail). subsequently) in which the solution is subjected to high voltage electrical discharges (step 25).

  The electric shock treatment consists of a series of discharges performed at a frequency of 0.5 Hz to 10 Hz.

  The electric generator which supplies the treatment chamber generates discharges of several tens of kilovolts (for example 40 kV) with a current of several thousand amperes (for example 5 kA).

  The shape of the voltage and current pulses is typically that of a damped sinusoid (Figure 3). The duration of a pulse is from a few microseconds to a few tens of microseconds.

  The solution is then suspended in an emulsion (step 26) in order to undergo a centrifugation (step 27) leading to obtaining a water with mucilage (to which a concentration step 28 is applied to obtain a concentrated solution in mucilage which can be subjected to an additional dehydration step to obtain a powder) and a second solid residue.

  According to a third phase of the process according to the invention, the second solid residue undergoes a second fractionation step, decomposing according to the present embodiment into a step 29 of treatment by high voltage electrical discharges, a stage of suspension in suspension. an emulsion and a centrifugation stage.

  At the end of this step 31, a third solid residue and an emulsion containing proteins are recovered, which is subjected to a membrane separation step leading to the production of an oil and a concentrated solution of proteins (at which can be subjected to an additional dehydration step to obtain a powder).

  According to a fourth phase of the process according to the invention, the third solid residue undergoes an oil extraction treatment preferably comprising an enzymatic digestion (step 32), the digestate being suspended in an emulsion (step 33) before undergoing a membrane separation step (step 34) leading to oil recovery and production of an ultimate waste residue.

  It is noted that the composition of the various fractions (resulting from the fractionation steps) can be adjusted by varying the parameters of the process (number of discharges, voltage, intensity, temperature).

  For example, for pulses of 40 kV at room temperature, the mucilage extraction phase (first fractionation step) is essentially carried out between 80 and 250 pulses. The second fractionation step will then be carried out between 250 and 1000 pulses.

  The water content is also adjustable before each extraction operation. Between each operation of the fraction washing operations can be performed to facilitate obtaining a particular type of molecule.

  Figure 4 shows the extraction cell in which is placed the raw material to undergo the treatment by electric shocks. Here is presented a discontinuous processing cell which can be replaced, according to other possible embodiments, by a processing cell in which is ensured a semi-continuous or continuous flow of the raw material.

  Such a chamber consists of an enclosure 41 hermetically closed by a cover 42 in which is formed a ventilation circuit 421.

  A tip electrode 43 is inserted into the chamber through the cover so as to face a planar electrode 44 placed at the enclosure base 44 coupled to an electrical circuit via a metal base.

  The electrodes 43, 44 connected to a high voltage generator are also capable of producing discharges in an aqueous solution 45 present in the chamber.

  Such a chamber is instrumented by electric current and voltage sensors, as well as by control software.

Claims (10)

  1. A process for extracting oil from oleaginous or proteinaceous seeds, comprising a grinding step and a cold pressing step, after which a fatty meal is obtained, characterized in that it comprises: a step grinding followed by a step of washing said fatcake to recover a first solid residue; a first step of fractioning said first solid residue to separate concentrated water into mucilage and a second solid residue; a second step of fractioning said second solid residue to separate a concentrated protein emulsion and a third solid residue; a step of treating said third solid residue to extract oil therefrom, said first and second fractionation steps including a high voltage electrical discharge treatment phase.   2. An oil extraction method according to claim 1, characterized in that said step of treating said third solid residue comprises an enzymatic digestion phase.   3. A method of extracting oil according to claim 2, characterized in that said enzymatic digestion phase is followed by an emulsification of said third digested residue and a membrane separation phase at the end of which said oil is extracted.   4. A method of extracting oil according to any one of claims 1 to 3, characterized in that it comprises a centrifugal flotation step of a low mucilage emulsion recovered at the end of said washing step. 10 15   5. A method of extracting oil according to any one of claims 1 to 4, characterized in that it comprises a membrane separation step of said protein-loaded emulsion.   6. A method of extracting oil according to any one of claims 1 to 5, characterized in that said first and second residues are dissolved in water in a water / meal ratio of 10/1 by mass. .   7. An oil extraction process according to claim 6, characterized in that it comprises a step of suspending said first residue and / or said second residue in an emulsion intended to undergo a centrifugation step.   8. An oil extraction method according to any one of claims 1 to 7, characterized in that said electric discharges have a voltage between about 30 kV and 50 kV.   9. A method of extracting oil according to claim 8, characterized in that said electric discharges have a voltage of about 40 kV.   10. An oil extraction method according to any one of claims 1 to 9, characterized in that said electric discharges are produced at a frequency of about 0.5 Hz to 10 Hz.