PROCEDURE FOR GRINDING MATERIALS OF PLANT ORIGIN, IN PARTICULAR PLANTS SUCH AS SEEDS.

Abstract

The invention relates to a process for grinding plant-based material, particularly plants such as seeds, to produce dehulled and / or fractionated flour, comprising the steps of performing compression grinding of a bed of plant-based material, performing a first air classification of the ground material to obtain a first fine fraction on one side and a first coarse fraction on the other side, performing a first post-treatment on the first fine fraction to obtain separate flour, and recycling the first coarse fraction to the grinding stage.

Description

The present invention relates to an innovative milling process for fractionating plant-based materials into different fractions (fibers, proteins, starches). Background Many plant-based food processing methods include a flour production stage. These flours can be the final products, considered as ingredients, or they can be an intermediate product in an overall process. The flour production process is therefore a key stage in many industries, particularly since it is often considered an energy-intensive stage. The list of plant-based materials that are often processed into flours is very diverse, but some examples include: - Cereals (wheat, buckwheat, oats, barley, corn, rice, etc.); - Legumes (peas, broad beans, lentils, beans, chickpeas, lupins, etc.); - Oilseed cake (sunflower, rapeseed, soybean, flaxseed, etc.); - Industrial or agricultural by-product (malt, bran, grain already used in brewing, straw, etc.); and - Other materials of plant origin or assimilated (algae, insects, etc.). Three families of flours can be listed regardless of the agronomic resource considered: wholemeal flours, hulled flours, and fractionated flours. Wholemeal flours are produced by milling the entire material without altering its chemical composition. The sole objective is to reduce particle size. The main examples of wholemeal flours are those made from cereals such as wheat or buckwheat. In these cases, the target particle size will be less than 500 µm and often less than 300 µm. The process is relatively simple, consisting of milling the entire material into flour with a specific particle size distribution. The goal is to reduce the particle size to a value with minimal energy consumption, investment, and processing steps. For food products, the limit is often related to fibers known to resist milling due to their elasticity and to oil content, which can cause the powder to become sticky.The present invention does not compete with established technologies in this market i bnn / cznz / e / Yi which are: wear mill, hammer mill, beater mill, impact mill... The present invention is not really adapted to fibers, because the energy consumption would be too high for this market. Hulled flours are those made from the inner part of the seeds without the outer fibers (known as hulls, husks, or bran). The goal here is to remove the fibers from the product. Depending on the raw material and the fiber's adherence, this hulling process is carried out either through pretreatment or directly during milling. The main examples of hulled flours are wheat flour (known as T45 and T55 flours), hulled legume flours, and corn flours. Two methods are available on the market, depending solely on the properties of the seed: If the hulls are loose and not attached to the seed (for example, in the case of legumes such as peas, broad beans / Vicia faba seeds, or lentils), then the hulls are removed before milling. Alternatively, the seeds are cracked or roughly broken to separate the hulls from the seed.Next, the hulls are separated from the seed by air separation, and at some point, the seed fraction is refined by optical sorting. The hulls can be further refined by sieving or other post-treatments (air sorting, electrical separation, etc.). Hulling technologies are numerous: impact hullers, abrasive mills, roller crushers, hammer mills, stone mills, etc. Therefore, the process often involves two to three machines before the feed enters the mill. Sometimes, costly pretreatment is required to increase hull separability: steaming, roasting, germination, etc. The challenge lies solely in the efficiency of the hulling process, the specific energy consumption, and the simplicity of the procedure. After removing the husks, the product can be ground into flour. Therefore, the goal is to reduce the particle size and particle size distribution to optimal values ​​with the lowest energy consumption and the fewest process steps (and therefore the lowest investment). A wide variety of mills are then possible: wear mills, hammer mills, beater mills, spike mills, impact mills, or roller mills, for example. When the hulls are strongly attached to the seed (for example, in the case of cereals or oilseeds), it is necessary to remove them during milling. The aim is to produce two fractions: the hulls (also called bran) and the fiber-free flour. In the past, stone mills were used to produce cereal flours. The compressive and frictional forces of the stones were used to grind the seeds. The fibers were then separated from the flour by sifting. The stone milling process is limited by its maximum capacity (often hundreds of kilograms per hour per machine at most) and the high energy consumption (75 kWh / ton) required to rotate a heavy stone weighing several tons. The present invention can be seen as a modern, safe, optimized, and robust version of the stone milling process. Stone mills were replaced in the 20th century by a milling system often composed of multiple rollers used to grind the seed while retaining the husks. The roller milling process is frequently used to process wheat flour, but also legumes, cereals, and oilseeds. The milling process is therefore highly progressive thanks to the multiple machines (up to 16 mills and 24 sieves). Pretreatment of the material is often required by adjusting the moisture content to control fiber elasticity. Generally, the moisture content is adjusted between 14 and 17%, and preferably between 15.5 and 16%. The contact time is usually a few hours (between 1 and 36 hours, but preferably between 4 and 18 hours).Despite the complexity of this process, energy consumption is considered low (approximately 35 kWh / ton), and the challenges lie in controlling product quality, often measured by the fiber content in the flour and the yields. The multiple operations necessitate constant (often manual) monitoring of the mill and require a significant construction size (generally four levels to maximize gravity flow and thus reduce product transportation costs). Many equipment suppliers have made various attempts to simplify the wheat flour production process. One such solution, proposed by Bühler (Alpesatm), consists of a compact line comprising a high-compression roller mill, a separator, and a sieve. The desired product is removed, while the intermediate fraction is returned to the roller mill via a recycling circuit. This process is attractive due to its small footprint, but it is limited by its energy consumption of 70 kWh / ton and its maximum capacity of 700 kg / h. The F10 milling process developed by Anutec involves the use of a spike mill coupled to a sieve. Moisture adjustment can be achieved with steam at a maximum of 60°C for only 10 minutes. The spike mill is set at 165 m / s. This process produces grey flour with an 80% yield. The limiting factor of this process is flour quality, but the company claims a significant reduction in energy consumption compared to small roller mill lines operating at 160 kWh / ton. This process is attractive due to its small footprint and low investment, but the poor flour quality is a limitation, as is the maximum capacity for a single unit, which will be approximately 2 tons / hour. The fractionated flour family refers to the production of flours enriched with protein, starch, and / or fiber. The goal is to create fractions enriched with protein, starch, or fiber. The main examples of fractionated flours are pea protein concentrates, wheat flours rich in gluten, and sunflower and rapeseed protein concentrates. The classic strategy is to deconstruct the material to separate a fine fraction and a coarse fraction with different chemical compositions. The process often begins with dehulled flour, thus requiring a complete dehulling line. The procedure typically consists of a micronization stage (PSD, i.e., particle size distribution, often <50 µm) along with a separator, which may be an air classifier and / or an electroseparator. The challenge lies in separating certain compounds (proteins, for example) into fractions with different particle sizes or electrostatic behavior than other compounds (starch or fibers). Particle size is often used as an indicator. However, the real objective is to separate particles based not only on their size but also on their density. In fact, the true challenge is the deconstruction of proteins, starches, and fibers.The protein must be ground while the internal fibers and starch must be preserved. Therefore, the grinding stage is crucial. It is usually carried out using an impact mill (the classic solution), a wear mill (lower energy consumption), or a double-bit mill (better product quality). Separation is then performed using an air classifier or, possibly, electrostatic separators. Energy consumption is an important consideration for these processes. The present invention competes with prior art approaches. It represents an innovative milling approach that combines the advantages of low energy consumption and excellent fiber / starch / protein separation. Brief description of the invention The present invention competes with all approaches when dehulled flour is required (without the possibility of producing cracked flour, for example). In fact, the invention allows simultaneous milling and hulling for most resources (cereals, pulses, and oilseed products). Milling is carried out to produce a flour of a few hundred millimeters while the hulls are produced as coarse fragments of a few millimeters. The process requires fewer machines than conventional processes and has a limited footprint. The energy consumption of the entire process is also among the lowest of all existing machines. It can also be fully automated and can process significant quantities of product (up to 10 tons / hour per unit). To this end, according to a first aspect, the present invention relates to a process for milling material of vegetable origin, in particular plants such as seeds, to produce dehulled and / or fractionated flour, comprising the steps of: - perform compression milling of a bed of material (MBC) of the plant-based material, - perform an initial air classification of the ground material to obtain a first fine fraction on one side and a first coarse fraction on the other side, - perform a first post-treatment on the first fine fraction to obtain separate flour, and - Recycle the first coarse fraction to the grinding stage. The invention will be implemented according to the different embodiments and variations set forth below, which should be considered individually or in any technically effective combination. Advantageously, since the material is hulled pea seeds, the first post-treatment consists of a second air sorting stage to produce a second coarse fraction of starch flour on one side and a second fine fraction of protein flour on the other side. Preferably, the procedure further comprises, prior to the compression grinding stage of a bed of material, a stage of mixing the plant-based material with water to hydrate the mixture and stabilize said hydrated mixture. According to another embodiment, said material being wheat grain, the first post-treatment provides wheat bran on one side and wheat flour on the other side. Preferably, the procedure also includes the following stages: - perform a second air classification of the first coarse fraction to obtain a second fine fraction on one side and a second coarse fraction on the other side, - perform a second post-treatment on the second fine fraction to obtain wheat bran on one side and wheat flour on the other, and - Recycle the second coarse fraction to the grinding stage. According to another embodiment, said material being pea seed, the first post-treatment provides pea hulls on one side and pea flour on the other. Preferably, the procedure also includes a sieving stage of the first coarse fraction to obtain pea hulls on one side and an intermediate fraction on the other. According to a particular aspect of the present invention, the procedure further comprises the steps of: - perform a second air classification of the intermediate fraction immediately after the sieving stage to obtain a second fine fraction on one side and a second coarse fraction on the other side, - perform a second post-treatment on the second fine fraction to obtain pea hulls on one side and pea seed grits on the other, and - Recycle the second coarse fraction and the pea seed grits to the milling stage. According to another embodiment, with the material being sunflower, the first post-treatment provides fibers on one side and sunflower protein flour on the other. Advantageously, the procedure also includes a stage of sieving the first coarse fraction to obtain fibers on one side and an intermediate fraction on the other. In particular, the procedure also includes the following stages: - perform a second air classification of the intermediate fraction immediately after the sieving stage to obtain a second fine fraction on one side and a second coarse fraction on the other side, - perform a second post-treatment on the second coarse fraction to obtain fibers on one side and sunflower semolina on the other, and - Recycle the second fine fraction and sunflower semolina to the milling stage. According to another embodiment, the material being legume seeds, the procedure further comprises, after the first air sorting, the following steps: nn i win / cznz / e / Yi - sift the first coarse fraction to obtain wholemeal or semi-wholemeal flour on one side and an intermediate fraction on the other side, and - recycle the intermediate fraction to the grinding stage. Brief description of the drawings Other advantages, purposes, and features of the present invention are evident from the following description, provided for explanatory purposes and not intended to be limiting, in relation to the accompanying drawings, in which: [FIG. 1] Figure 1 is a general scheme of the present invention, [FIG. 2] Figure 2 is a schematic of a first example, [FIG. 3] Figure 3 is a schematic of a second example, [FIG. 4] Figure 4 is a schematic of a third example, [FIG. 5] Figure 5 is a schematic of a fourth example, [FIG. 6] Figure 6 is a comparison table, [FIG. 7] Figure 7 is another comparison table, [FIG. 8] Figure 8 is a schematic of a fifth example, and [Fig. 9] Figure 9 is a diagram of a sixth example. Detailed description of the achievements The present invention comprises a material bed compression mill (MBC) (e.g., pendulum mill, vertical roller mill, horizontal roller mill, hydraulic roller press) together with air classifier(s) and / or screening stages. This compression milling process was chosen for its ability to maximize flour heterogeneity and for its low specific energy consumption (kWh / ton). The MBC mill is a technology commonly used in the mining industry for decades. It revolutionized the cement industry in the 1990s, replacing ball mills (which were low-cost but energy-intensive). Its advantages include high robustness, low maintenance frequency, and low specific energy consumption. In milling plant-based materials, flour production is often a matter of fiber preservation rather than achieving a specific particle size. However, fiber preservation creates highly heterogeneous flours that are avoided by mill suppliers and users. The principle of the invention is, therefore, to exploit this heterogeneity of the powder in plant-based materials to gain an advantage in terms of product quality, process efficiency, and process cost. The procedure consists of: - A moisture adjustment stage to control fiber elasticity and therefore preservation in the mill, - An MBC mill, which works on the principle of compression, as it is efficient in reducing the particle size of the brittle fractions (flours) while preserving the size of the fiber fraction, - An air classifier to control the residence time of each fraction in the mill by controlling both the size and density of the particles, and - Various post-treatments to refine the rejects from the air classifier (for husk removal) by sieving, air classification or electroseparation. The material bed compression mill (MBC) uses compressive and frictional forces (without slippage) applied on a compacted bed of material (the bed thickness varies from 10 mm to 100 mm depending on the mill size) at a low roller speed (less than 10 m / s). The MBC milling process provides better preservation of starch and fibers, compared to other milling processes (e.g., impact and / or high-speed wear). The MBC mill also offers improved efficiency and consequently reduces electrical energy consumption per ton of production compared to other grinding processes. In fact, the maximum power output is transmitted directly to the material bed. The MBC grinding process with low-speed compression of a material bed produces a low abrasion rate, which increases the service life of the grinding media and consequently reduces product contamination, compared to other grinding processes, and reduces maintenance costs. The volume of the MBC mill chamber (e.g., pendulum mill, vertical roller mill) can be used to simultaneously dry the product during the grinding process, using hot gas at the mill inlet. Alternatively, or in addition, if the MBC chamber volume is too small or unavailable, drying can also be achieved within the gas circuit of the dynamic classifier. The drying rate can be controlled by a temperature setpoint i bnn / cznz / e / Yi located at the outlet of the mill or classifier. To produce flour, a dynamic classifier can be combined with the MBC mill. The fineness of the flour is managed by the classifier's configuration (gas flow control, classifier turbine speed control). This solution offers two main advantages compared to a milling solution without a classifier: The first advantage is a stable product quality, regardless of fluctuations in the material's behavior. The harder / softer the material, the greater / less the circulating load returning from the classifier to the mill to maintain a constant flour fineness; The second advantage is the ability to fully feed the mill up to its rated power, in order to maximize production capacity, while the fineness of the product is still ensured by the classifier, compared to a solution without any classifier where the mill must also manage the fineness of the product, which can limit the feed and prevent the use of the mill's rated power. The invention is mostly adapted to two cases: the production of hulled flours and the production of fractionated flours. The invention consists of a milling process capable of grinding plant-based materials (plants, for example, especially seeds) into flour with maximum fiber preservation. This process is suitable for many known applications but provides a significant improvement in terms of quality, performance, investment, or operating cost. The invention is applicable whenever a fiber fraction needs to be removed from the production of flour from plant-based materials. The general procedure described in Figure 1 consists of: - An optional but recommended conditioning stage in which the product is prepared for milling. Preparation often consists of a hydration phase. This increase in moisture content aims to make the fibers softer and more elastic to improve fiber preservation during milling. Moisture adjustment is limited to a few percentages (+1% to +10%) with a contact time ranging from a few minutes (1 minute) to several hours (up to 36 hours), but often between 30 minutes and 18 hours. Moisture adjustment can be combined with other treatments such as steaming, disinfection (ozone, bleach, etc.), microwave treatment, germination, etc. - A single-stage MBC grinding mill. This mill operates using compressive and frictional forces applied by roller(s) to a bed of particles. The force is fixed (typically from a hydraulic jack or centrifugal force for a pendulum mill), and the bed thickness is variable (typically between 10 and 100 mm depending on the roller size). The rolling force of the roller on the bed material induces compressive and frictional stress (without slippage) throughout all the particles beneath the roller. Therefore, it differs from a roller mill (fixed spacing between rollers) when the material is in contact with steel. Most MBC mills (e.g., pendulum mills or vertical roller mills) also utilize high ventilation, which prevents excessively high heating temperatures and can be used to dry the product.This ventilation flow is also used for transporting particulate product to the classifier. As an example, the MBC mill can be the Carousel pendulum mill model patented by POITTEMILL, with its externalized handling mechanics and oil lubrication to avoid the risk of product contamination. - A dynamic classification stage. An air classifier collects the product exiting the mill and separates it into two fractions. The fraction distribution, known as the cut size, can be set by adjusting the classifier's turbine speed. The fine fraction typically consists of flour and large husk fragments, or, if ultrafine grinding is the goal, protein fractions. The coarse fraction comprises products that are not fine enough or not sufficiently dissociated. These two fractions are then further processed for refining. The coarse fraction that comes out of the first classifier can be: - Further process in a sieving or electroseparation stage to remove coarse fragments of the husks. This fraction may contain some large seed fragments and can be further processed in a second classifying unit to remove the light fraction and thus recycle the seed to the MBC mill; - Subsequently process in a second air classifier to remove the fine fraction (which may be starch or any intermediate fraction). The coarse fraction from this second air classifier is recycled to the MBC mill for regrind. This second subsequent procedure is described in a separate POITTEMILL patent for double classification; - Subsequently processed in a second air classifier to remove the coarse fraction (which may be the coarser fiber fraction), the fine fraction from the second air classifier is recycled to the MBC mill to be ground again. This third subsequent procedure is described in a separate POITTEMILL double classification patent; and - Recycle as is in the MBC mill, to be ground again. The fine fraction may consist of flour and hulls, dehulled flour, or protein concentrate. This fraction may be further processed by sieving, air classification, and / or electrostatic separation. This post-treatment aims to remove the fine fibers generated during the process. Additional post-treatment that does not affect the chemical composition is not part of the invention. The general scheme of the procedure with all its options is illustrated in Figure 1. All the options (lines) are shown in the following figures, but are not fully activated. Therefore, the invention includes a simplified version applied to the milling of plant-based materials. The following examples highlight the adaptation of this general scheme of the procedure to specific situations. Example 1: dehulling wheat flour from wheat grain When applied to wheat flour production, the innovative scheme procedure according to Figure 2 is used to produce white or grey flour with a significant simplification of the conventional roller mill procedure. The procedure consists of: - An optional but recommended conditioning stage in which the wheat grain is prepared for milling. Preparation consists of a hydration phase. This increase in moisture content aims to make the fibers softer and more elastic, thus improving fiber preservation during milling. Moisture adjustments are made in small percentage increments (+1% to +10%) with a contact time ranging from a few minutes (1 minute) to several hours (up to 36 hours), but often between 30 minutes and 18 hours. Moisture adjustment can be combined with other treatments such as steaming, disinfection (ozone, bleach, etc.), microwave treatment, germination, etc. - An MBC grinding stage, as already described; - A dynamic classification stage. An air classifier collects the product coming out of the mill and separates it into two fractions. The fine fraction is generally composed of flour and large fragments of husks. The coarse fraction is composed of products that are not fine enough or not sufficiently dissociated. These two fractions are subsequently treated to refine them; The coarse fraction from the first classifier is then processed in a second classifier to remove the fine fraction (which may be starch or any intermediate fraction). The coarse fraction from this second classifier is recycled in the MBC mill. The fine fractions may consist of flour and husk fragments. These fractions may be further processed by sieving, air classification, and / or electrostatic separation. This post-treatment aims to remove the fine fibers generated during the process. Further post-treatment that does not affect the chemical composition is not part of the invention. This procedure can be applied with minor modifications to all native or processed cereals, legumes, oilseed cakes and flours, and some industrial by-products. In the following example, the wheat moisture content was adjusted to 15.5% with a contact time of 18 hours. MBC milling was performed using a pendulum mill. The turbine of the first classifier was set to produce flour from 0-300 µm, and the second classifier was set to extract maximum bran. Each air classifier collects its fine fraction, which is then sieved to 200 µm. The flour was collected on sieves that passed the fraction, while the bran was collected on sieves that retained the fraction. The specific energy consumption of the mill is 32 kWh / t. The process produces high-yield wheat flours (71.5% - 23.8% bran) with an ash content of 0.95%. The starch damage level is relatively low, at 10.22% (starch-based). Example 2: Pea flour hulling from pea seed When applied to the production of shelled pea flour, the innovative scheme shown in Figure 3 represents a significant simplification of the conventional process. In fact, the shelling and milling process is carried out in just a few stages compared to the conventional process consisting of a shelling line followed by a milling line. Furthermore, it is less energy-intensive. The procedure consists of: - An optional but recommended conditioning stage in which the pea seed is prepared for milling. This preparation often consists of a hydration phase. This increase in moisture content aims to make the fibers softer and more elastic, thus improving fiber preservation during milling. i bnn / cznz / e / Yi Humidity adjustment is in small percentage increments (+1% to +10%) with a contact time ranging from a few minutes (1 minute) to several hours (up to 36 hours), but often between 30 minutes and 18 hours. Humidity adjustment can be combined with other treatments such as steam, disinfection (ozone, bleach, etc.), microwave, germination, etc. - An MBC grinding stage, as already described; - A dynamic classification stage. An air classifier collects the product exiting the mill and separates it into two fractions. The fine fraction generally consists of flour and large fragments of husks, or, if the objective is ultrafine grinding, it will consist of protein fractions. The coarse fraction consists of products that are not fine enough or not sufficiently dissociated. These two fractions are subsequently treated for refining. The coarse fraction exiting the first air classifier can be further processed in a sieving stage to remove coarse fragments of husks. This fraction may contain some large seed fragments and can be further processed in a second air classifier to remove the light fraction and thus recycle the grain semolina back to the mill. The fine fraction may consist of flour fragments and husks. This fraction may be further processed by sieving and / or electrostatic separation. This post-treatment aims to remove the fine fibers generated during the process. Additional post-treatment that does not affect the chemical composition is not part of the invention. In the following example, the moisture content of the peas was adjusted to +3% with a contact time of 1 hour. MBC milling was performed using a pendulum mill. The first classifier turbine was set to produce 0-50 µm flour, and a 2 mm sieve was used to remove 6% of the hulls from the feed (without any air classifier). The process produces a 0-50 pm shelled pea flour, for a specific mill energy consumption of 63 kWh / t. The same procedure can also be used to produce 0-315 pm shelled pea flour with a specific mill energy consumption of 23 kWh / t. Example 3: Production of pea protein concentrate from pea seeds When applied to the production of pea protein concentrate, the innovative scheme procedure according to Figure 4 provides significant energy savings and greater efficiency compared to conventional procedures. The procedure consists of: - A dehulling stage in which the product is prepared for milling. Dehulling can be combined with other treatments such as steam, disinfection (ozone, bleach, etc.), microwave, germination, etc.; - An MBC grinding stage, as already described; - A dynamic classification stage. An air classifier will collect the product coming out of the mill and separate it into two fractions. The fine fraction is generally composed of flour containing the dissociated protein particles. The coarse fraction is composed of products that are not fine enough or not sufficiently dissociated; - The coarse fraction that comes out of the first classifier is recycled in the MBC mill; - The fine fractions may consist of fine protein particles and coarse starch and fiber particles. These fractions are subsequently processed by a second air classification. This post-treatment aims to extract protein from the fine fraction and starch and fiber from the coarse fraction; The remaining fibers, both fine and coarse fractions, can be removed by electrostatic separation generated during the process. Further post-treatment that does not affect the chemical composition is not part of the invention. In the following example, the milling of dehulled pea seeds containing protein was carried out using a pendulum mill. The turbine of the first classifier was set to produce 0-50 ppm flour, and the second classifier was set to extract the concentrated protein flour. The specific energy consumption of the mill is 41 kWh / t. The process produces a 55% protein-concentrated flour with a high yield (55-65%). The level of damaged starch is relatively low, at 5.7% (starch-based). Example 4: production of sunflower protein concentrate When applied to the production of sunflower meal concentrate, the innovative scheme procedure according to Figure 5 provides significant energy savings and greater efficiency compared to conventional procedures. The procedure consists of: - An optional but recommended conditioning stage in which the product is prepared for milling. Preparation consists of a hydration phase. This increase in moisture content aims to make the fibers softer and more elastic to improve fiber preservation during milling. The moisture adjustment is in small percentage increments (+1% to +10%) with a contact time ranging from a few minutes (1 minute) to several hours (up to 36 hours), but often between 30 minutes and 18 hours. The moisture adjustment can be combined with other treatments such as steaming, disinfection (ozone, bleach, etc.), microwave treatment, germination, etc. - An MBC grinding stage, as already described; - A dynamic classification. An air classifier will collect the product coming out of the mill and separate it into two fractions. The fine fraction is generally composed of flour fragments and fibers. The coarse fraction is composed of products that are not fine enough or not sufficiently dissociated; - The coarse fraction is recycled directly in the mill; The fine fraction may consist of flour and husks, dehulled flours, or protein concentrate. This fraction may be further processed by sieving, or by a second classification using air and / or electrostatic separation. This post-treatment aims to remove the fine fibers generated during the process. Additional post-treatment that does not affect the chemical composition is not part of the invention. In the following example, the moisture content of the sunflower meal was not adjusted. Milling was performed using a pendulum mill. Only one classifier was used, and it was set to produce 0-500 µm flour. The coarse fraction is returned to the mill. The fine fraction exiting the classifier is sieved to 125, 180, 250, and 315 µm. The specific energy consumption of the mill is 30 kWh / t. The process produces a protein-rich fraction with a yield and quality similar to that of a roller mill. The installation is smaller and the specific energy consumption is lower. Figures 6 and 7 show two different tables derived from an example of sunflower concentration yield compared to a roller mill chart. Example 5: Variation in the production of dehulled sunflower protein In this particular embodiment according to Figure 7, the first coarse fraction exiting the first air classifier can be further processed in a sieving stage to remove the coarse fiber fragment. This fraction may contain some large sunflower fragments and can be further processed in a second air classifier to remove the light fraction and thus recycle the sunflower seed to the mill. The fine fraction exiting the second air classifier is recycled to the mill. The coarse fraction is further processed by sieving and / or electrostatic separation. Further post-treatment that does not affect the chemical composition is not part of the invention. This option considerably reduces the specific energy consumption of the mill (approximately 40% with sunflower flour). Example 6: Low-cost production of protein from legumes When applied to the production of protein concentrate from legumes, the innovative scheme procedure according to Figure 9 provides significant energy savings compared to conventional procedures. The procedure consists of: - An optional but recommended conditioning stage in which the product is prepared for milling. Preparation consists of a hydration phase. This increase in moisture content aims to make the fibers softer and more elastic, thus improving fiber preservation during milling. Moisture adjustments are made in small percentage increments (+1% to +10%) with a contact time ranging from a few minutes (1 minute) to several hours (up to 36 hours), but often between 30 minutes and 18 hours. Moisture adjustment can be combined with other treatments such as steaming, disinfection (ozone, bleach, etc.), microwave treatment, germination, etc. - An MBC grinding stage, as already described; - A dynamic classification. An air classifier will collect the product coming out of the mill and separate it into two fractions. The fine fraction is generally composed of a protein-rich fraction. The coarse fraction is composed of flour and husks; - The coarse fraction is sieved to collect a fraction of flour and husks, while the intermediate fraction is recycled in the mill; The hull fraction may consist of flour and hulls. This fraction can be further processed (using a gravity classifier, for example) to purify the hulls and recycle the large seed fragments in the mill. The procedural schemes according to the present invention are based on a specific innovation of the mill in the grinding of plant-based materials, giving multiple options for pre-treatment or post-treatment operations. The process uses compressive forces to mill the flour fraction i win / cznz / e / Yi while preserving the fibers. Separation stages allow for control of the flour fineness and fiber removal, and pretreatments further enhance fiber preservation. The process can be fully automated, is robust, and has lower overall energy consumption than conventional methods. The application of this technology will be central to every procedure that uses flours of vegetable origin and the production of ingredients such as the production of hulled flours, white flours, protein concentrates, optimal flours for protein isolates and starch purification. The detailed description of the subject matter of the invention, given by way of illustration only, shall in no way constitute a limitation, and technical equivalents are also within the scope of the present invention.

Claims

1. A process for grinding plant-based material, particularly plants such as seeds, to produce dehulled and / or fractionated flour, comprising the steps of: - performing compression grinding of a bed of plant-based material, - performing a first air classification of the ground material to obtain a first fine fraction on one side and a first coarse fraction on the other side, - performing a first post-treatment on the first fine fraction to obtain separate flour, and - recycling the first coarse fraction to the grinding stage.

2. A method according to claim 1 wherein the material is hulled pea seeds, the first post-treatment consists of a second air sorting stage to produce a second coarse fraction of starch flour on one side and a second fine fraction of protein flour on the other side.

3. A method according to claim 1, further comprising, prior to the MBC milling stage, a stage of mixing the plant-based material with water to hydrate the mixture and stabilize said hydrated mixture.

4. A method according to claim 3 wherein said material being wheat grain, the first post-treatment provides wheat bran on one side and wheat flour on the other side.

5. A process according to claim 4, further comprising the steps of: - performing a second air classification of the first coarse fraction to obtain a second fine fraction on one side and a second coarse fraction on the other, - performing a second post-treatment of the second fine fraction to obtain wheat bran on one side and wheat flour on the other, and - recycling the second coarse fraction to the milling stage.

6. A method according to claim 3 wherein said material being pea seed, the first post-treatment provides pea hulls on one side and pea flour on the other side.

7. A method according to claim 6, further comprising a sieving step of the first coarse fraction to obtain pea hulls on one side and an intermediate fraction on the other.

8. A method according to claim 7, further comprising the steps of: - performing a second air classification of the intermediate fraction immediately after the sieving stage to obtain a second fine fraction on one side and a second coarse fraction on the other side, - performing a second post-treatment of the second fine fraction to obtain pea hulls on one side and pea seed grits on the other side, and - recycling the second coarse fraction and the pea seed grits to the milling stage.

9. A method according to claim 3 wherein, said material being sunflower, the first post-treatment provides fibers on one side and sunflower protein flour on the other side.

10. A method according to claim 9, further comprising a sieving step of the first coarse fraction to obtain fibers on one side and an intermediate fraction on the other side.

11. A method according to claim 10, further comprising the steps of: - performing a second air classification of the intermediate fraction immediately after the sieving stage to obtain a second fine fraction on one side and a second coarse fraction on the other side, - performing a second post-treatment of the second coarse fraction to obtain fibers on one side and sunflower semolina on the other side, - recycling the second fine fraction and the sunflower semolina to the milling stage.

12. A process according to claim 1 wherein the material being legume seeds, further comprising, after the first air classification, the steps of: 5 - sieving the first coarse fraction to obtain wholemeal or semi-wholemeal flour on one side and an intermediate fraction on the other side, and - recycling the intermediate fraction to the milling stage.

Images