Clear, water-soluble plant fraction

Abstract

The present invention relates to a method for filtering steep water to obtain a water-soluble plant fraction such as clear corn steep water or a clear solution of potato solubles, as well as to the filtering method for producing same, and industrial uses thereof.

Description

CLEAR WATER-SOLUBLE PLANT FRACTION Field of invention

[0001] The present invention relates to clear water-soluble plant fractions, particularly clear corn steeping solution and clear potato solubles solution. These can be stored for several days at room temperature without the occurrence of a deposit of insoluble materials. Technological background

[0002] The food industry commonly fractionates plants to separate different constituents such as starch or fibers. To do this, the person skilled in the art frequently uses fractionation by solubility difference, particularly in an aqueous solution. The plant, particularly its seeds or tubers, after reduction to flour, is suspended in water. Since certain compounds such as starch are insoluble in water, it is then easy to recover them by simple centrifugation, for example. At the end of this step, a co-product is also generated, consisting of different soluble compounds such as salts, sugars, and amino acids. These co-products can be defined as the soluble aqueous fractions of plants, these said fractions containing insolubles suspended in the aqueous phase.

[0003] For example, potato starch extraction has been practiced industrially for several decades. The potato, after harvesting and washing, is ground in the presence of water. The starch and pulp, another name for the fibers present in the potato, are then separated by centrifugation because they are insoluble in water. The residual solution called "potato juice" will then undergo heating to coagulate the coagulable proteins. These are then also recovered by centrifugation. A final residual aqueous solution called "potato solubles" is also obtained, containing soluble proteins, including amino acids, soluble sugars and salts. minerals. These potato solubles are then concentrated to approximately 30-50% dry matter. These potato solubles are an example of a “water-soluble fraction” of plants.

[0004] Corn steep water, commonly referred to as "com-steep" by those skilled in the art, refers to an aqueous solution resulting from steeping corn.

[0005] Steeping corn in water is the first step in starch extraction in wet starch production. This steeping process allows the corn grains to swell and removes highly fermentable soluble matter from these grains. It consists of keeping the corn in silos for a given time in hot water containing a small amount of sulfur dioxide, in order to facilitate the subsequent separation of protein, cellulose, and starch, and also to prevent the growth of undesirable microorganisms. These steeping waters are then most often concentrated, typically by evaporation.

[0006] Two essential phenomena take place simultaneously during steeping: the first consists of a diffusion of soluble materials from the corn grain into the steeping water, while the second consists of a fermentation of these soluble materials in the steeping water by lactic bacteria, the steeping conditions (presence of sulfites, reducing sugars, temperature) being favorable to the rapid development of this bacterial flora.

[0007] The main interest of these concentrated steeping waters, commonly called by their English name "com-steep" by those skilled in the art, lies in their composition of essential nutrients, resulting from the transfer of soluble matter from the grain. These nutrients constitute favorable factors for the growth of microorganisms as well as for the production of secondary metabolites, and make corn steeping water an ideal source of nutrients in the fermentation, agriculture and agronomy industries.

[0008] In fact, corn steeping water constitutes a source of organic nitrogen of choice due to the distribution and forms of its amino acids: free, peptide, protein as well as a source of carbon (lactic acid) and phosphate (lactic acid). phytic) with delayed effect. A high content of vitamins and trace elements completes the interest that corn steeping water represents as a nutrient source for the growth of microorganisms and the induction of secondary metabolites when corn steeping water is combined with one or more carbon sources (glucose, maltodextrin, starch, sucrose, etc.).

[0009] Furthermore, it is a relatively inexpensive source of nutrition, compared to yeast extracts which represent the reference material in this field, and which are also used in human and animal food.

[0010] Furthermore, it is known that the use of corn steeping water as a replacement for complex nitrogen sources such as cotton or soy proteins can substantially increase the yields of antibiotic production by fermentation.

[0011] Corn steeping water is also an excellent source of nutrition for growing plants in soil or above ground. Its richness in nitrogen, phosphate, and potassium nutrients is particularly suited to the needs of growing plants. It also contains numerous micro and trace elements, a saline richness, and amino acids / peptides that potentially have biostimulatory effects on plant growth. Its use not only nourishes the plant but also protects it from various diseases that can compromise its growth.

[0012] However, corn steeping water in liquid form as well as potato solubles pose settling problems over time, which is particularly troublesome for the transport, storage and pumping of the product. The settling of heavier insoluble materials causes heterogeneity of the mixture. It must be stored in stirred tanks, thermostatically controlled to limit the evolution of its composition, which is impractical and expensive. In addition, these insoluble particles, even in suspension, can clog the dispersion nozzles when using them during dispersion using nozzles, for example when spreading corn steeping water or potato solubles on crop fields. This is especially true when Corn steeping water or potato solubles are consumed in small quantities at a time by some fermentation industries. In this case, it is particularly important to control its conservation.

[0013] Patent application JP2001204410 proposes using a centrifugation process to remove these insoluble particles that settle and to stabilize the corn steeping water. However, it should be noted that the process is not optimal because the corn steeping water obtained is not completely clear (7% minimum volume precipitation in the supernatant). Such a product is therefore likely to cause problems during implementation, for example by blocking dispersion nozzles when spreading on crop fields.

[0014] The applicant has also worked on this problem and proposed a solution described in patent WO2021 / 074548. This method for treating a corn steeping water solution comprises the following steps: a) adding neutral divalent cation salts to the corn steeping water solution; b) adjusting the pH of the corn steeping water solution between 6 and 8; c) separating the liquid and solid phases of the solution obtained in step b) and d) drying the liquid phase obtained in step c) in order to obtain a powdered corn steeping water. If this solution makes it possible to obtain a clear corn steeping water that is stable during sterilization, its composition is changed by the introduction of salts. If this modification is useful for particular applications, it may be advantageous to retain the initial protein content as well as the composition of the original corn steeping water.

[0015] This issue has also been addressed, particularly in Govender E's master's thesis "The purification of corn steep liquor as a fermentation feedstock by ultrafiltration" published in 2010. Govender E proposes several solutions consisting of different pretreatments such as the rectification of the pH of the corn steep liquor to 7 with the addition of ammonium hydroxide, the use of a centrifugal decanter or "gyratory screens". These pretreatments of the corn steep liquor solution are then followed by an ultrafiltration step. However, although the rectification of the pH to 7 allows for the reduction of precipitates In corn steepwater after sterilization, a large part of the nutrients are removed by this pretreatment and this corn steepwater is not recommended for fermentation. Moreover, as will be demonstrated in the examples this process is carried out at a high temperature in order to facilitate filtration. The disadvantage is that some insoluble particles are solubilized, permeate through the membrane and redecant during storage.

[0016] The skilled person is still waiting for a process allowing the production of clear water-soluble plant fractions, particularly a clear corn steeping water solution and a clear potato soluble solution and remaining clear even after storage at room temperature for at least 30 days.

[0017] It is to the plaintiff's credit that he worked on all of these issues and found the inventive solution which will be described in more detail in the following chapters. Summary of the invention

[0018] According to a first aspect, the invention relates to a water-soluble plant fraction characterized in that it comprises a content of settleable insoluble particles of less than 0.5%; preferably less than 0.25%; even more preferably 0%.

[0019] Preferably, the water-soluble plant fraction will be corn steeping water characterized in that it comprises a content of settleable insoluble particles of less than 0.5%; preferably less than 0.25%; even more preferably 0%.

[0020] Alternatively, the water-soluble plant fraction will be a solution of potato solubles, characterized in that it comprises a content of settleable insoluble particles of less than 0.5%; preferably less than 0.25%; even more preferably 0%.

[0021] According to one embodiment, the water-soluble plant fraction, preferably selected from corn steeping water and potato soluble solution, according to the invention is preferably characterized in that it comprises insoluble particles which have a particle size distribution whose modal value is between 0.01 microns and 10 microns. In the case where the water-soluble plant fraction is corn steeping water, the modal value is preferably between 0.01 microns and 0.8 microns; preferably between 0.05 microns and 0.5 microns; preferably between 0.05 microns and 0.3 microns.

[0022] In the present invention, the term "microns", particularly when referring to particle size, means "micrometers".

[0023] According to one embodiment, the water-soluble plant fraction, preferably selected from corn steeping water and potato soluble solution, according to the invention is characterized in that its protein content on total dry matter is between 25% and 50%. In the case where the water-soluble plant fraction is corn steeping water, its protein content on total dry matter is between 35% and 50%, preferably between 37% and 47%, even more preferably between 40% and 45%.

[0024] According to a second aspect, the invention relates to a method for filtering a water-soluble plant fraction, preferably selected from corn steeping water and potato solubles solution, in which the water-soluble plant fraction, preferably selected from corn steeping water and potato solubles solution, to be filtered is filtered using a filter aid selected from potato starch, cellulose, diatomaceous earth and perlite, preferably to obtain as filtrate a water-soluble plant fraction, preferably selected from corn steeping water and potato solubles solution, as defined in the first aspect of the invention.

[0025] According to one embodiment, the method according to the invention is a method in which: - The water-soluble fraction of plants, preferably selected between corn steeping water and potato soluble solution, to be filtered is placed in the presence of the filtration aid to form a mixture, then the mixture is filtered through a filter medium, and / or - a pre-layer of the filter aid is formed on a filter medium and then the corn steeping water to be filtered or the mixture is passed through the pre-layer, wherein the pre-layer is formed by bringing together a filter aid selected from perlite, potato starch, cellulose, and diatomaceous earth with water to form a mixture, and then the mixture is filtered through a filter medium, to obtain a pre-layer comprising the filter aid.

[0026] According to one embodiment, the method according to the invention comprises the following steps: 1. the provision of a water-soluble fraction of plants, preferentially selected between corn steeping water and potato soluble solution, to be filtered 2. the preparation of a filtration system comprising a filter medium on which is formed a pre-layer comprising a filtration aid chosen from perlite, potato starch, cellulose, and diatomaceous earth, 3. filtration of the water-soluble fraction of plants, preferably selected between corn steeping water and potato soluble solution, from step 1 using the filtration system of step 2, 4. optionally, conditioning of the water-soluble fraction of plants, preferably selected between corn steeping water and potato soluble solution, obtained in step 3 for future use or direct use of the filtration permeate.

[0027] According to another embodiment, the method according to the invention comprises the following steps: 1. the provision of a water-soluble fraction of plants, preferably selected between corn steeping water and potato soluble solution, to be filtered 2. Bringing together the filtration aid chosen from perlite, potato starch, cellulose, and diatomaceous earth, with the water-soluble fraction, preferably selected from corn steeping water and potato soluble solution, to form a mixture 3. filtration of the mixture from step 2 using a filtration system, 4. Optionally, conditioning of the water-soluble fraction of plants, preferably selected between corn steeping water and potato soluble solution, obtained in step 3 for future use or direct use of the filtration permeate.

[0028] According to one embodiment, the method according to the invention uses perlite as a filtration aid.

[0029] According to one embodiment, the method according to the invention is implemented in a vacuum drum filter.

[0030] According to an alternative embodiment, the method according to the invention is implemented in a filter press.

[0031] According to one embodiment, the method according to the invention is characterized in that the filtration is carried out at a temperature between 20°C and 80°C, preferably between 20°C and 60°C, preferably 20°C and 40°C.

[0032] According to a third aspect, the invention relates to the industrial use of the water-soluble fraction of the plant, preferably steeping water or a solution of potato solubles, according to the first aspect of the invention or obtained according to the process as defined in the second aspect of the invention, as a nutrient substance, for example for the preparation of culture media for the fermentation industry or for feeding plants in agriculture.

[0033] The invention will be better understood with the aid of the detailed description which follows in the following chapters. Detailed description of the invention

[0034] By "water-soluble plant fraction" or its synonyms "aqueous plant fraction", "soluble plant fraction", "solution of plant solubles" or "aqueous plant extract", is meant according to the invention the fractions comprising the different water-soluble constituents of a plant seed or a plant tuber. These fractions are made up of the different water-soluble molecules, obtained after elimination and / or extraction of the different insoluble fractions. For example, a fraction made up of salts, sugars and / or amino acids remaining in solution in an aqueous solvent after suspension of a plant seed flour, followed by extractions of the different insoluble compounds such as starch or internal fibers may be mentioned.

[0035] By "water-soluble" compound, we mean the capacity of any compound to be solubilized in an aqueous solvent, preferably water.

[0036] By "solubilize" we obviously mean the common meaning of solvation but also any compound suspended in water and which cannot be separated by centrifugation, filtration, coagulation or precipitation processes. The solvent of the aqueous solution will preferably be at room temperature. By "room" we mean a temperature between 5°C and 25°C, preferably between 10°C and 20°C, even more preferably between 12°C and 18°C. The pH of the aqueous solution will preferably be close to neutral or neutral. By "close to neutral" we mean a pH between 5.5 and 8.5, preferably between 6.0 and 8.0. By "neutral" we mean a pH between 6.5 and 7.5, preferably 7.0

[0037] For the purposes of the present invention, the term "corn steep", "steep water", "CSL liquor", "corn soluble extract", "steep water", "concentrated corn steep", "low MS process water" means the liquid fraction consisting of steep water from corn grain steeping silos. The liquid fraction of a conventional steep water, which can be filtered using the method of the invention, typically has a dry matter content of between 10% and 50%, preferably between 30% and 50%, even more preferably between 40% and 50% and usually has a protein nitrogen content expressed as N6.25 of approximately 45% of the dry matter weight. Corn steepwater usually contains pythic acid at a content of 6 to 10% of the dry matter weight, lactic acid at a content of 25% and 30% of the dry matter weight of lactic acid and ash at a content of approximately 15 to 20% of the dry matter weight.

[0038] Generally speaking, corn steeping water is produced from corn seeds using a standard state-of-the-art process known as corn steeping. As previously described in the introduction, steeping corn in water is the first step in starch extraction in wet starch production. This steeping process allows the corn grains to swell and eliminates highly fermentable soluble materials contained in these grains. It consists of maintaining the corn placed in silos for a given time (called steeping time) in hot water containing a small amount of sulfur dioxide, in order to facilitate the subsequent separation of proteins, cellulose, and starch, and also to prevent the growth of undesirable microorganisms.

[0039] Two essential phenomena take place simultaneously during steeping: the first consists of a diffusion of soluble materials from the corn grain into the steeping water, while the second consists of a fermentation of these soluble materials in the steeping water by lactic bacteria, the steeping conditions (presence of sulfites, reducing sugars, temperature) being favorable to the rapid development of this bacterial flora.

[0040] Preferably, the person skilled in the art will be able to use the teaching of US patent 4,359,528 or those described in patent applications EP 724841 and EP 819702 belonging to the applicant.

[0041] By "potato solubles solution" or "potato solubles" is meant the soluble aqueous fraction obtained after elimination of the various insoluble constituents, more precisely after extraction of the starch, pulps and thermocoagulable proteins. The conventional "potato solubles" fraction, which can be filtered with the method of the invention, typically has a dry matter content of between 30% and 50%, preferably between 32% and 48%, even more preferably between 35% and 45% and usually has a protein nitrogen richness expressed as N6.25 of between 30% and 35% of the weight of the dry matter.

[0042] The Applicant's patent FR2496689 presents an example of a process for doing this. First, the potato is disintegrated in an aqueous medium so that its constituent cells are crushed, and so that the starch and pulp (fibers) can then be separated from the resulting slurry or grated material. The "red waters" (the traditional name for the fraction thus obtained) are then depleted of proteins by carrying out a physicochemical coagulation of these proteins (heating at isoelectric pH). The residual fraction obtained after coagulation is considered to be a "potato solubles solution".

[0043] According to a first aspect, the invention relates to a water-soluble plant fraction characterized in that it comprises a content of settleable insoluble particles of less than 0.5%; preferably less than 0.25%; even more preferably 0%.

[0044] Preferably, the water-soluble fraction will be corn steeping water characterized in that it comprises a content of settleable insoluble particles of less than 0.5%; preferably less than 0.25%; even more preferably 0%.

[0045] Alternatively, the water-soluble fraction will be a solution of potato solubles, characterized in that it comprises a content of settleable insoluble particles of less than 0.5%; preferably less than 0.25%; even more preferably 0%.

[0046] The water-soluble plant fraction, preferably corn steeping water or potato soluble solution, according to the invention has the advantage of being clear, and preferably remains clear even after storage at room temperature, i.e. a temperature of 20°C + / - 2°C for at least 30 days.

[0047] The term "clear", when referring to the water-soluble fraction of the plant, preferably corn steeping water or potato solubles solution, earth, according to the invention, means that the water-soluble fraction of plant, preferably corn steeping water or potato soluble solution, according to the invention is free or almost free of decantable insoluble particles.

[0048] In the present invention, the expression "insoluble particles" means particles consisting of insoluble materials of a water-soluble fraction of a plant, preferably corn steeping water or potato solubles solution.

[0049] The expression "settlable insoluble particles" means insoluble particles of a water-soluble fraction of a plant, preferably corn steeping water or potato soluble solution, which have the property of settling after storage of the corn steeping water at room temperature, i.e. a temperature of 20°C + / - 2°C, for at least 30 days.

[0050] The water-soluble plant fraction, preferably corn steeping water or potato solubles solution, according to the invention is characterized in that it comprises a content of less than 0.9%, preferably less than 0.8%, a content of less than 0.5%; preferably less than 0.25%; even more preferably 0% (i.e. is free) of settleable insoluble particles.

[0051] Preferably, the water-soluble plant fraction, preferably corn steeping water or potato soluble solution, according to the invention is free of decantable insoluble particles.

[0052] The content of settleable insoluble particles is preferably measured using the following test A: 1. Introduction of 160 ml of soluble aqueous plant fraction, preferably corn steeping water or potato soluble solution, into a cylindrical container 10 cm high and 5 cm in diameter, then closing the container, 2. Storage of the soluble aqueous fraction of the plant, preferably corn steeping water or potato soluble solution, thus conditioned for 30 days at an ambient temperature of 20°C + / - 2°C, 3. Observation of the absence or presence of a deposit of insoluble particles at the bottom of the cylindrical container, 4. If there is a deposit, measure its height in order to calculate the reference percentage of the height of the container.

[0053] Thus, if for a water-soluble plant fraction, preferably corn steeping water or a potato solubles solution, tested, a deposit with a deposit height of 1 cm is observed at the end of Test A, the content of settleable insoluble particles is calculated as follows: 1 cm (height of the deposit) / 10 cm (height of the cylindrical container 10 cm high and 5 cm in diameter) = 0.1 = 10%. If, for a water-soluble plant fraction, preferably corn steeping water or a potato solubles solution, tested, no deposit is observed at the end of Test A, the content is considered to be zero (0 cm / 10 cm = 0 cm), in other words, the water-soluble plant fraction, preferably corn steeping water or the potato solubles solution, is considered to be free of settleable insoluble particles.

[0054] The water-soluble plant fraction, preferably corn steeping water or potato soluble solution, according to the invention, if it contains few or no settleable particles, may still contain insoluble particles whose particle size, in particular the modal value, can be measured by laser particle size analysis, as for example according to Test B detailed below.

[0055] According to one embodiment, the water-soluble plant fraction, preferably selected from corn steeping water and potato soluble solution, according to the invention is preferably characterized in that it comprises insoluble particles which have a particle size distribution whose modal value is between 0.01 microns and 10 microns. In the case where the water-soluble plant fraction is corn steeping water, the modal value is preferably between 0.01 microns and 0.8 microns; preferably between 0.05 microns and 0.5 microns; preferably between 0.05 microns and 0.3 microns.

[0056] The terms "modal value", "Dmode", "mode" or "dominant value" can be used interchangeably. The modal value is well known to those skilled in the art. Generally speaking, it corresponds to the most represented value of any variable in a given population. It generally corresponds to the maximum of the relative frequency curve. In the case of a distribution into classes of equal amplitudes, the modal class designates the one with the highest number. The convention is then to call the center of the modal class mode.

[0057] Preferably, the particle size distribution and subsequent calculation of the modal value is carried out using Test B as follows: - The equipment used is preferably a MALVERN MASTERSIZER 3000 for wet dispersion. The wet dispersion system is preferably the HYDRO LV module with a dispersion volume of 600ml. The liquid is placed in a tank equipped with an ultrasonic transducer (to facilitate sample dispersion and eliminate bubbles) resistant to strong acids. - The software integrated into the MASTERSIZER 3000 controls all measuring functions, product delivery in dispersion and cleaning. - The measuring range is from 0.01 pm to 3500 pm. - Before analysis, the environment (lenses and circuit) must be clean. The background analysis must be less than 100 in energy on the first detector (the curve profile must be a decreasing exponential). - The sample is dispersed directly, generally in a solvent: demineralized water (Refractive Index = 1.33). The stirring is 1900 rpm. When adding the sample, the obscuration must be between 5% and 10% and stable before measurement. - The optical model must be adapted to the sample according to the MIE theory. - Data collected in volume mode automatically includes the modal value or Dmode which is the diameter of the main population of the particle size distribution.

[0058] Preferably, the dry matter of the water-soluble plant fraction, preferably corn steeping water or potato soluble solution, according to the invention is between 40% and 60% dry matter, preferably between 42% and 55%, even more preferably between 42% and 50%.

[0059] The dry matter is measured using any protocol usable by a person skilled in the art. Preferably, the following so-called desiccation method is used: ■ The necessary equipment is as follows: - Oven-dried sand at 103°C - Ventilated oven set at 103°C ± 2°C - Glass crystallizer with a diameter of 70 mm - Small glass rod previously dried in an oven (4-1) - Oven set at 80°C ± 2°C allowing operation under reduced pressure between 0 and 135 mbar. - Desiccator equipped with an effective desiccant - Analytical balance to 1 / 1000th of a gram ■ Test taking - In a crystallizing dish, add about 15 to 20 g of sand and a small glass stirrer. Place the whole thing in an oven for at least 1 hour, then in a desiccator and cool to room temperature. - Weigh, introduce a test portion of approximately 2 to 3 g, exactly weighed, of the sample to be analyzed and homogenize using the glass stirrer. ■ Drying - Place this crystallizer in the oven, maintaining a reduced pressure of between 0 and 135 mbar. After at least 4 hours, disconnect the vacuum pump and allow the oven to slowly fill with air, until atmospheric pressure is reached. Remove the crystallizer and place it in the desiccator. - Let cool to room temperature and reweigh. ■ The dry matter expressed as a percentage by mass, of the product as is, is given by the formula: ( (m1- m2) * 100 ) / mO - mO is the mass, in grams, of the test sample - m2 is the mass, in grams, of the crystallizer + sand + stirrer - m1 is the mass, in grams, of the crystallizer + sand + stirrer + product after drying - Express the result to the nearest 0.1 unit.

[0060] Preferably, the water-soluble plant fraction, preferably corn steeping water or potato soluble solution, according to the invention is characterized in that its protein content on total dry matter is between 35% and 50%, preferably between 37% and 47%, even more preferably between 40% and 45%.

[0061] The total protein content can be determined by any protocol well known to those skilled in the art, such as the determination of the total amount of amino acids. Preferably, the total nitrogen will be determined using the Dumas method and the value will be multiplied by the coefficient 6.25. Method according to the invention

[0062] According to a second aspect, the invention relates to a method for filtering a water-soluble plant fraction, preferably a corn steeping water or a potato solubles solution, in which a water-soluble plant fraction, preferably a corn steeping water or a potato solubles solution, to be filtered is filtered using a filter aid selected from potato starch, cellulose, diatomaceous earth and perlite, preferably to obtain as filtrate a water-soluble plant fraction, preferably a corn steeping water or a potato solubles solution according to the first aspect of the invention.

[0063] According to one embodiment, the method according to the invention is a method in which: - the water-soluble fraction of the plant, preferably the corn steeping water or the potato soluble solution to be filtered, is placed in the presence of the filter aid to form a mixture, then the mixture is filtered through a filter medium, and / or - a pre-layer of the filter aid is formed on a filter medium and then the water-soluble plant fraction, preferably corn steeping water or the potato soluble solution to be filtered or the mixture, is passed through the pre-layer, wherein the pre-layer is formed by bringing together a filter aid selected from perlite, potato starch, cellulose, and diatomaceous earth with water to form a mixture, and then the mixture is filtered through a filter medium, to obtain a pre-layer comprising the filter aid.

[0064] According to one embodiment, the method according to the invention comprises the following steps: 1. the provision of a water-soluble plant fraction, preferably corn steeping water or a solution of potato solubles to be filtered 2. the preparation of a filtration system comprising a filter medium on which is formed a pre-layer comprising a filtration aid chosen from perlite, potato starch, cellulose, and diatomaceous earth, 3. filtration of the water-soluble plant fraction, preferably corn steeping water or potato solubles solution from step 1 using the filtration system from step 2, 4. optionally, conditioning of the water-soluble plant fraction, preferably corn steeping water or a solution of potato solubles obtained in step 3 for future use or direct use of the filtration permeate.

[0065] According to another embodiment, the method according to the invention comprises the following steps: 1. the provision of a water-soluble fraction of plants to be filtered 2. Bringing together the filtration aid chosen from perlite, potato starch, cellulose, and diatomaceous earth, with the water-soluble fraction to form a mixture 3. filtration of the mixture from step 2 using a filtration system, 4. Optionally, conditioning of the water-soluble plant fraction obtained in step 3 for future use or direct use of the filtration permeate.

[0066] According to one embodiment, the method according to the invention uses perlite as a filtration aid.

[0067] According to one embodiment, the method according to the invention is implemented in a vacuum drum filter.

[0068] According to one embodiment, the method according to the invention is implemented in a filter press.

[0069] According to one embodiment, the method according to the invention is characterized in that the filtration is carried out at a temperature between 20°C and 80°C, preferably between 20°C and 60°C, even more preferably between 20°C and 40°C. In the case where the water-soluble fraction of plants is corn steeping water, the temperature will preferably be between 20°C and 60°C, even more preferably between 20°C and 40°C.

[0070] Preferably, the invention consists of a process for producing a water-soluble plant fraction, preferably corn steeping water or a solution of potato solubles, comprising the following steps: 1. Provision of a quantity of water-soluble plant fraction, preferably corn steeping water or a solution of potato solubles to be treated 2. Preparation of a filtration system containing a filter aid selected from the list of perlite, potato starch, cellulose, and diatomaceous earth 3. Filtration of the water-soluble plant fractions, preferably from corn steeping water or potato solubles solution from step 1 using the filtration system from step 2 4. Optionally, packaging for future use or direct use of the filtration permeate.

[0071] The water-soluble plant fraction, preferably from a corn steeping water or a potato solubles solution from step 1, may be produced by any known method, for example as described in paragraphs 27 to 29, 38 to 40 or 42.

[0072] Alternatively, it is of course possible to acquire a water-soluble fraction of the plant, preferably corn steeping water or a previously produced solution of potato solubles.

[0073] The second step of the process according to the invention consists of the preparation of a filtration system containing a filtration aid selected from the list comprising perlite, potato starch, cellulose, diatomaceous earth.

[0074] By "filtration system", according to the invention, is meant any system containing a filter medium allowing the retention of particles present in corn steeping water, typically selected from the list of vacuum or pressure filters. Among those under pressure, we find press filters, vertical frame filters, candle filters, horizontal or vertical frame filters and in the list of vacuum filters, we find rotary drum filters, rotary table filters, rotary disc filters and in particular vacuum drum filters.

[0075] Vacuum drum filters are well known to those skilled in the art. This type of device typically contains one or more pumps, a drum, a sizing tank and a scraper.

[0076] The vacuum is produced by 1 or 2 pumps, typically "liquid ring" pumps, which ensure a constant vacuum inside the drum. The vacuum created causes the liquid to be drawn through the adjuvant layer. The drum is cylindrical, covered with a filter cloth. It usually rotates at an adjustable speed around its horizontal axis. It is partially submerged in a trough equipped with an agitator. There are two types of drum: sector drums and total vacuum drums. The sector drum is divided into sectors that do not communicate with each other. The filtrate is evacuated using the vacuum pump to an independent collector that ensures air / liquid separation. The drum A total vacuum drum is not divided and is completely vacuumed. In a total vacuum drum, the filtrate is transferred directly to a storage tank using an extraction pump submerged in the lower part of the drum. The sizing tank is a tank equipped with an agitator that ensures the homogeneity of the water / adjuvant mixture. Its volume is proportional to the surface area of ​​the filter media. The scraper tank (or scraper) ensures the elimination of the clogged layer throughout the filtration.

[0077] The term “filter media” means any filter surface typically used for industrial liquid filtration, and in particular the filter surface of the filtration system defined above. This filter media is typically a filter cloth, a filter mesh, a filter non-woven fabric, for example a filter cloth for a filter press or filter belts, a filter mesh for a pressure or vacuum filter. The filter media may be made of any suitable material, typically metal, nylon, polypropylene, polyester, viscose, or polyethylene.

[0078] The terms "filtrate" and "filtration permeate" refer to a liquid that has passed through a filter medium, in other words a liquid obtained after filtration.

[0079] According to the invention, the term "filter aid" means any compound or mixture of compounds which makes it possible to improve the quality and / or the filtration flow rate by adding it to the liquid to be filtered and / or by depositing it beforehand on the filtering surface of the filtration system in the form of a pre-layer.

[0080] Filter aids consist mainly of mineral or organic powders, used as a pre-coat to improve the performance of filtration systems. The aid is diluted in a liquid (filtered liquid, liquid to be filtered or water) and then deposited on the filter. The pre-coat then forms on the surface of the filter media. It is possible to add varying quantities of this filter aid during the filtration cycle to create a filter "cake" that remains porous around the filter; this is called alluviation. The first quantities of filtrate are often downgraded, sometimes until the dry matter of the product to be treated is reached.

[0081] According to the invention, the term "perlite" or "expanded perlite" means a volcanic rock composed mainly of silica. After extraction, this rock is usually thermally expanded to obtain a very fine honeycomb structure and then crushed and sieved to obtain precise particle size cuts. A particular commercial example is the product CLARCEL FLO produced by the company Chemviron which is an expanded perlite, whose CAS number is 93763-70-3. Preferably,

[0082] According to the invention, "potato starch" means a more or less purified starch produced by the potato fractionation process.

[0083] According to the invention, the term "cellulose" means the polysaccharide of the [3-D-glucan] series. Its repeating unit is cellobiose: it consists of two |3-D-glucopyranoses (glucoses) in their 4C1 chair conformation joined by a [31-4] glycosidic bond. Cellulose is the most abundant organic molecule on earth: this natural homopolymer is the main constituent of the cell wall of many plants (and in particular plants and trees) with a content varying from 15% to 99%. A particularly suitable commercial example is the product ARBOCEL® BWW 40 produced by JRS Rettenmaier.

[0084] According to the invention, "diatomaceous earth" means a variety of diatomite, a siliceous sedimentary rock of organic and fossil origin, consisting of fossilized remains of diatoms. It is also called kieselguhr, kieselgur, celite (lexicalized brand name, used in chemistry), or infusorial earth. The grain size of kieselguhr is generally between 10 and 200 pm. It is soft and very light due to its high porosity. This latter property allows it to be used for filtration in industry, particularly for wine and brewing.

[0085] Preferably, the adjuvants will have a permeability expressed in Darcy between 0.030-15; preferably between 2.5 and 4.6; even more preferably between 2.5 and 3.5

[0086] Preferably, the filtration will be carried out by bringing the water-soluble fraction of the plant, preferably from corn steeping water or a solution of potato solubles to a temperature between 20°C and 80°C, preferably between 20°C and 40°C, preferably between 25°C and 35°C. In the case where the water-soluble fraction of plants is corn steeping water, the temperature will preferably be between 20°C and 60°C, even more preferably between 20°C and 40°C

[0087] After filtration, the water-soluble fraction can be supplemented with various products / compounds, such as preservatives such as sorbic acid, benzoic acid, sodium bisulfite, acetic acid, or lactic acid. The water-soluble fraction can be stored in this way, but it can be concentrated by evaporation or spray-dried, for example.

[0088] The invention finally relates to the use of the water-soluble plant fraction, preferably corn steeping water or a solution of potato solubles according to the invention in any industry, in particular in the industries of industrial fermentation, agriculture, agronomy and plant nutrition / stimulation.

[0089] The water-soluble plant fraction, preferably from corn steeping water or a solution of potato solubles according to the invention, can advantageously be used as a nutrient in the preparation of culture media for the fermentation industry, nutrient media for feeding plants in agriculture. In particular, for growing lettuce and tomatoes.

[0090] The water-soluble plant fraction, preferably corn steeping water or a solution of potato solubles according to the invention, is of particular interest when spreading on cultivated soils using nozzles.

[0091] It can also be used in the fields of food, animal nutrition or others.

[0092] The invention will be better understood with the aid of the following examples, which are not intended to be limiting and only show certain embodiments and certain advantageous properties of the water-soluble plant fraction, preferably of a corn steeping water or a solution of potato solubles according to the invention. Brief description of the drawings

[0093] Other characteristics, details and advantages of the invention will appear on reading and analyzing the attached drawings, in which:

[0094] [Fig. 1] shows the experimental device for generating liquid quenching water according to the prior art. Examples

[0095] The following examples serve to better understand the invention, while not restricting it to them.

[0096] Example 1: Preparation of corn steeping water according to prior art EP0026125

[0097] Corn steeping water is obtained according to a known process, set out in patent document EP0026125.

[0098] To produce the corn steeping water, a battery of silos [Figure 1] is used, consisting of seven stainless steel silos S1 to S7, with a filter bottom, with a total volume of 33 litres and a diameter of 25 cm, which can be filled with corn M and each equipped with: - a level 10 probe, - a pipe 11 connecting the bottom of a given silo, on the one hand, to the head of the following silo by a pipe 12 and, on the other hand, to the head of the silo itself by a pipe 13 ensuring the recirculation of the liquid phase on the silo itself or towards the following silo, this pipe also serving to draw off the quenching water at the required time, - a large diameter 14 bottom valve for emptying the corn, - thermoregulated bain-marie 16 with as many circulation pumps P ensuring the circulation of the liquid phase from a given silo through the heating coil to the next silo or to the head of the silo in question, - seven sets of two solenoid valves 17 and 18 placed respectively on pipes 12 and 13 and controlled by the level probe (ensuring a perfect covering of the corn and movement of the liquid throughout the battery), - a sulphurized water inlet pipe 19, adjusted to 1.5 g / l of sulphur dioxide, from which the sulphurized water is distributed at a constant flow rate, ensuring a constant circulation rate (litres of water per kg of corn), successively on each silo, by opening the corresponding valve V1, - a 20-litre tank (not shown) receiving the steeping water from the silos before crushing the corn and connected to each of the silos by pipes C1 to C7 respectively branched off on pipes 11 of each silo, the direction of the steeping water leaving a given silo towards pipe 11 or pipe C being ensured using a valve V2 and V3 respectively, - an evaporator not shown (of the type marketed by KURT HERBERT Apparate- und Maschinenbau Lahr, Baden). Every day, the collected quench water is evaporated to 50% dry matter using this vacuum evaporator, at a temperature below 60°C.

[0099] The corn used is French corn, sourced from traditional suppliers to the starch industry. The chosen soaking time is 40 hours and the SO2 level is set at 1.5 g / litre.

[0100] The temperature is set at 48°C±1°C throughout the battery. The 40-hour time is obtained for working on five silos with emptying every eight hours.

[0101] The water circulation rate was gradually increased from 0.8 to 1.0 - 1.5 then 1.8 liters of water per kg of commercial corn.

[0102] Example 2: Tests for the removal of settleable insoluble particles using a centrifugation system possibly combined with prior and / or subsequent chemical and / or thermal treatment steps

[0103] In this example, we seek to eliminate the settleable insoluble particles from the corn water obtained at the end of Example 1.

[0104] A first strategy for the removal of insoluble particles tested consists of using centrifugal force, as described in patent application JP2001204410, by adding prior and / or subsequent steps of chemical and / or thermal treatment in order to facilitate / improve the performance of the removal of insoluble particles.

[0105] A Sorval RC Evolution centrifuge was used. Different centrifugation forces were tested, possibly in combination with different chemical and / or thermal pre / post treatments in order to facilitate / improve the performance of removing insoluble particles. The different tests are detailed in Table 1 below: [Table 1] Abbreviations used in Table 1: GG: Guar gum; GX: Xanthan gum, SDS: Sodium dodecyl sulfate; AS: Sodium alginate.

[0106] The results show that whatever the parameters applied (centrifugal force from 3500G to 12,000G, use of pre / post treatments) it was impossible to go below 1% of suspended particles. Laser granulometry was only used a little here because the size of particles that settle in this way is automatically greater than 0.8 microns. This result is consistent with the teaching of patent application JP2001204410 (7% minimum volume precipitation in the supernatant).

[0107] Example 3: Tests for the removal of settleable insoluble particles using a filtration system with filter aids

[0108] In this example, we seek to remove the settleable insoluble particles from the corn water obtained at the end of Example 1 according to a second strategy using a filtration system.

[0109] The filtration system used is a rotary vacuum filter, called a vacuum drum, implemented using filtration aids in the form of a precoat (“precoat filtration” in English).

[0110] Several filter aids were tested. A pre-coat of each of the aids detailed below was made using approximately 30 kg of product, suspended in drinking water and then placed on the filter surface of the drum composed of a filter cloth with a surface area of ​​approximately 2 m 2 before proceeding with filtration. A corn steeping water produced via a process as described in Example 1 was therefore filtered in a vacuum drum with different filter aids.

[0111] The filtrate obtained was then analyzed. The results are presented in the Table 2 below: [Table 2]

[0112] Observation of the results shows us that: - The use of potato starch, cellulose, diatomaceous earth and perlite allows the obtaining of a filtrate free of insoluble particles according to Test A. - Using a combination of potato starch and Arbocel BWW4030 / 05 cellulose (in a 50 / 50 mass ratio) results in corn steeping water containing 5% insoluble particles according to Test A after filtration, and therefore does not appear to work. - Some filter aids do not allow corn steeping water to be obtained free of insoluble particles according to Test A, such as wood flour. - The use of perlite allows the production of a filtrate free of insoluble particles according to Test A, even with a very high filtration flow rate, which is very advantageous from an industrial point of view.

[0113] Example 4: Influence of filtration temperature on the quality of the filtrate obtained

[0114] In this example, the filtration equipment consists of a vacuum pump, a Buchner funnel, and a 100 micron mesh wire mesh. A cake of approximately 2 cm thick filter aid was built on the filter mesh with deionized water before the actual filtration began.

[0115] The quenching water is rectified if necessary to 43% dry matter (by adding demineralized water and / or by evaporation). Different samples are preheated overnight at 20°C, 30°C, 40°C and 50°C. Filtration is then carried out.

[0116] The filtrate obtained is then analyzed. Table 3 below summarizes the results obtained: [Table 3]

[0117] The results show that the use of potato starch as a filtration aid allows the required quality to be obtained, but the filtration must be carried out at a temperature lower than or equal to 40°C. It is found that a higher filtration temperature, for example 45°C, will cause deterioration of the quality of the filtrate obtained. Without being bound by any theory, it is considered by the applicant that a temperature above 40°C causes solubilization of the insoluble matter particles and allows permeation of these. As the permeate cools, the insoluble matter reprecipitates in the form of particles.

[0118] Example 5: Use of ultrafiltration to treat corn steeping water

[0119] We reproduce the teaching of Govender E's master's thesis "The purification of corn steep liquor as a fermentation feedstock by ultrafiltration" published in 2010.

[0120] The test was carried out on an ultrafiltration module equipped with a 30KD PALL® tangential filtration cassette.

[0121] The quenching water used is Solulys E48. After stirring, the quenching water is centrifuged to remove as much insoluble matter as possible, as described in Govender's thesis.

[0122] During this time, the ultrafiltration cassette is rinsed (because it is stored in 0.1 N NaOH) and a water flow test is carried out to check the integrity of the cassette (Flow rate before storage: 345570g / b / min. Flow rate after storage: 312453g / b / min).

[0123] A first ultrafiltration test was carried out at a temperature of 30°C. The membrane became clogged very quickly, with zero flow rate. It was impossible to generate permeate in order to investigate its storage stability according to Test A. After disassembly, an accumulation of product was observed at the inlets. The cassette could not be recovered after numerous washes (water flow rate was too low).

[0124] A second test is carried out at a temperature of 40°C. The permeate obtained is stored under the conditions of Test A. A deposit according to Test A greater than 1% is observed. The temperature allows a sufficient quantity of permeate to be generated but at the cost of its quality.

[0125] Example 6: Production of a solution of potato solubles according to the invention

[0126] First, a potato solubles solution with a settleable insoluble particle content according to test A of approximately 0% was prepared by rotary vacuum filtration with an aid. The filter aid tested was potato starch. A pre-coat was made using approximately 50 kg of potato starch, suspended in drinking water and then placed on the filter surface of the rotary filter drum, consisting of a filter cloth of approximately 2 m 2 before filtering the potato solubles. The potato solubles were therefore filtered in a vacuum drum at room temperature. The resulting filtrate, herein referred to as the potato solubles solution, was analyzed. The results are shown in Table 4 below.

[0127] Table 4

[0128] In a second step, a potato soluble solution was prepared by filtration on a filter press. A filter aid, in this case FILTRACELL NF1100 wood fiber (supplied by Rettenmaier), was used in alluvial treatment. The total filtration surface area of ​​the said filter press was approximately 1.12 m 2 . The potato solubles to be filtered, maintained at 20°C and supplemented with 3% Filtracell NF1100 wood fibers, were fed to the filter press. The filtrate was obtained after force-feeding and compacting. The filtration rate of the two phases combined was approximately 25 kg / h / m2 on average. The percentage of insoluble particles decantable according to test A in the obtained filtrate was measured equal to approximately 0%.

[0129] Example 7: Use of corn tempeh waters and potato solubles in application in a plant culture

[0130] We chose to evaluate the performance of the water-soluble plant fractions according to the invention in plant cultures

[0131] The model plant chosen is lettuce (Val d'orge variety).

[0132] The culture protocol is as follows: - Controlled growth cabinet (temperature 24°C at night and 21°C during the day; photoperiod 16 h; humidity 60%) - Negative control soil: soil with N / P / K ratio 14 / 10 / 8 - Positive control soil: soil adjuvanted with chemical fertilizer with N / P / K ratio 20 / 20 / 20 + TE - Potting soils with water-soluble fraction (see Table 3 below) - The different soils have the same quantity of nitrogen, i.e. 2.31g per plant - Each modality is composed of 12 pots of 1 plant, or 12 plants per modality - Duration of cultivation since application of the product: 3 weeks

[0133] To evaluate performance we evaluate: - The amount of new wet, dry and chlorophyll matter in the leaves - The amount of new wet and dry matter and the length of roots

[0134] The results are given in the following Table 5:

[0135] Table s

[0136] We therefore note that: - The water-soluble fractions of corn and potato are at least as effective as the control with chemical fertilizer Treatment with the method according to the invention even allows an increase in performance whether on the growth of leaves or roots.

[0137] The absence of insoluble particles that can be decanted also allows dispersion by nozzle without annoying clogging.

[0138] Example 8: Comparison of corn steeping water according to the teaching of WQ2021 / 074548.

[0139] Corn steeping water according to WO2021 / 074548 is produced.

[0140] This is stored under the conditions of Test A. A deposit greater than 1% is observed.

[0141] The process according to WO2021 / 074548 makes it possible to obtain corn steeping water that generates little or no insoluble precipitates when it is subjected to sterilization. The technical problem is different, the product does not make it possible to obtain a total or almost total absence of insoluble precipitates.

Claims

Claims

1. Water-soluble plant fraction characterized in that it comprises a content of settleable insoluble particles of less than 0.5%; preferably less than 0.25%; even more preferably 0%.

2. Water-soluble plant fraction according to claim 1 characterized in that it is corn steeping water.

3. Water-soluble plant fraction according to claim 1 characterized in that it is a solution of potato solubles

4. Water-soluble fraction according to claims 1 to 3, characterized in that it comprises insoluble particles which have a particle size distribution whose modal value is between 0.01 microns and 0.8 microns; preferably between 0.05 microns and 0.5 microns; preferably between 0.05 microns and 0.3 microns.

5. Water-soluble fraction according to claims 1 to 4, characterized in that its protein content on total dry matter is between 35% and 50%, preferably between 37% and 47%, even more preferably between 40% and 45%.

6. A method of filtering a water-soluble plant fraction, preferably selected from corn steeping water and a potato solubles solution, wherein a water-soluble plant fraction, preferably selected from corn steeping water and a potato solubles solution, to be filtered is filtered using a filter aid selected from perlite, potato starch, cellulose, and diatomaceous earth, preferably to obtain as filtrate a water-soluble fraction, preferably selected from corn steeping water and a potato solubles solution, as defined in one of claims 1 to 5.

7. A method according to claim 6, wherein: - the water-soluble fraction of the plant, preferentially selected between water corn steeping solution and a solution of potato solubles, to be filtered, is brought into contact with the filter aid to form a mixture, then the mixture is filtered through a filter medium, and / or - a pre-layer of the filter aid is formed on a filter medium and then the water-soluble fraction of the plant to be filtered or the mixture is passed through the pre-layer, wherein the pre-layer is formed by bringing together a filter aid selected from perlite, potato starch, cellulose, and diatomaceous earth with water to form a mixture, and then the mixture is filtered through a filter medium, to obtain a pre-layer comprising the filter aid.

8. A method according to any one of claims 6 or 7, comprising the following steps:

1. the provision of a water-soluble plant fraction, preferably selected between corn steeping water and a solution of potato solubles, to be filtered 2. the preparation of a filtration system comprising a filter medium on which is formed a pre-layer comprising a filtration aid chosen from perlite, potato starch, cellulose, and diatomaceous earth, 3. filtration of the water-soluble plant fraction, preferably selected between corn steeping water and potato solubles solution, from step 1 using the filtration system of step 2, 4. optionally, conditioning of the water-soluble plant fraction, preferably selected between corn steeping water and a potato soluble solution, obtained in step 3 for future use or direct use of the filtration permeate.

9. Method according to any one of claims 6 to 8, characterized in that it uses perlite as a filtration aid.

10. Method according to any one of claims 6 to 9 characterized in that it is implemented in a vacuum drum filter.

11. Method according to any one of claims 6 to 9, characterized in that it is implemented in a filter press.

12. Method according to claims 6 to 11 characterized in that the filtration is carried out at a temperature between 20°C and 80°C, preferably between 20°C and 60°C, even more preferably between 20°C and 40°C.

13. Industrial use of a water-soluble plant fraction according to claims 1 to 5 or obtained according to the process as defined in any one of claims 6 to 12 as a nutrient, for example for the preparation of culture media for the fermentation industry or for feeding plants in agriculture.

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