EP1247579B1 - Process for extracting hard wheat germs and installation for carrying out the process - Google Patents

Description

The present invention relates to the general technical field of processes, installations and devices used and implemented in the agri-food field, and for example in the flour mill or semolina, to ensure the extraction or separation of grains, products or parts thereof. grains from harvested plants, including cereals.

The present invention relates to a method and a facility for extracting durum wheat germ in its natural state, that is to say having not previously undergone its extraction any operation or step of conditioning, treatment or conservation, the germ of durum wheat and the mass of cereals harvested being in its natural physicochemical state.

It is already known to carry out purification and cleaning operations of a cereal mass formed by common wheat, the use of which is widespread owing in particular to its high starch content. Since common wheat, in its natural state, has a low brittle consistency that does not give rise to natural fragmentation, it is then possible to ensure the purification and separation of the interesting food parts of a wheat harvest by proven techniques and classics. Such techniques use in particular a series of smooth cylinders on which the wheat crop passes. The separation of common wheat from the various waste present in the crop, as well as the possible separation of common wheat sprouts, can be easily obtained because of the crushing tendency of soft wheat and its non-fragmentation, which then, by passing through a series of sieving devices or sizing, to ensure the separation of the various ingredients.

Conventional scrubbing, cleaning and separation techniques used for soft wheat are not applicable to crops and seeds of plants with higher mechanical hardness and strength characteristics, mainly because of their natural tendency to fragmentation into wheat. many particles. These characteristics complicate the processes for extracting and cleaning such seeds of plants if one wishes to preserve the physical and physiological completeness of the seed that one wishes to separate, or of fragments of seeds that one wishes to separate as well. .

This is the reason why the techniques known to date in terms of extraction of undifferentiated seeds or fractions from durum wheat all imply a preconditioning of the durum wheat, namely a prior humidification phase, with a view precisely to attempting to resolve the natural tendency to break up durum wheat. Thus, a known technique for extracting from durum wheat consists, after dry cleaning of the mass to be treated, of conditioning the mass to be treated with a water supply preceding a step of transformation and separation of the wheat, the germ and waste by a series of successive steps including grinding, sieving and purification or sassage.

This known extraction technique gives acceptable results, but nevertheless suffers from various disadvantages. Thus, it turns out that the need for prior humidification of the grain necessarily implies at the end of the extraction process to obtain products having a relatively high humidity, which is opposed to good preservation of the final product . This is the reason why this prior art requires the addition of an additional heat treatment at the end of treatment. Of course, the additional heat treatment constitutes an additional cost for the process, which constitutes an industrial handicap. Moreover, the heat treatment is generally accompanied inevitably by a transformation of the taste of the product obtained, or the particular organoleptic qualities resulting from the supply of heat (toasted taste in particular).

It also turns out that the known prior art operating wet is not able to provide an overall yield of sufficient extraction process, since it allows to recover a tiny fraction of wheat germ present in the mass treated, precisely because of the operating conditions related to the chosen wetland.

Finally, and in the case where the final heat treatment is insufficient, there is then the occurrence of rancidity of the wheat germ obtained, precisely related to the inadequacy of the final heat treatment.

Document is also known FR-2 404 467 a method of degerming maize consisting essentially of repressing and grinding dry or moist maize in a cylindrical annular working chamber by swirling it with rapidly turning pallets and fixed in large numbers on a rotor and separating the seeds of the endosperm by the outwardly oriented edges of the pallets. Such treatment, whether done by the dry or wet route, is not suitable for durum wheat seed, which has dimensional, anatomical and physiological characteristics quite different from that of a corn kernel.

The object of the invention is therefore to remedy the various disadvantages listed above, and to propose a new process. and a new seed extraction plant that makes it possible to obtain durum wheat germ whose initial organoleptic qualities are preserved, while being simple and easy to implement on an industrial scale.

Another object of the invention is to propose a new process and a new extraction plant that are able to provide, with the aid of simple means, an acceptable yield of the extraction operation of the durum wheat germ.

Another object of the invention is to propose a new method and a new extraction system that are able to use, without any significant change, conventional separation and cleaning units in the field.

The objects assigned to the invention are achieved by means of a method of extraction in its natural state of durum wheat germ in which, from a harvested durum mass containing a heterogeneous mixture of grains, of germs and waste or impurities, successively and gradually ensures the separation of the germ to recover it, said method being carried out by a series of extraction steps exclusively mechanical and dry, without external liquid supply.

• une première unité de nettoyage de la masse de blé dur récoltée,
• au moins une première unité de séparation mécanique pour réaliser la première étape de séparation,
• au moins une seconde unité de séparation pour réaliser la seconde étape de séparation,
• au moins une unité de tamisage pour réaliser l'étape de tamisage,
• au moins une unité d'épuration pour réaliser l'épuration terminale.

The objects assigned to the invention are also achieved by means of an installation for carrying out the extraction process in its natural state of durum wheat germ according to one of claims 1 to 10 comprising:

• a first cleaning unit of the harvested durum wheat mass,
• at least a first mechanical separation unit for carrying out the first separation step,
• at least one second separation unit for performing the second separation step,
• at least one sieving unit for carrying out the sieving step,
• at least one purification unit for carrying out the terminal purification.

• La figure 1 représente, selon une vue schématique, un diagramme synthétique et schématique d'une variante préférentielle du procédé d'extraction conforme à l'invention.

Other objects and advantages of the invention will be explained in more detail on reading the description which follows, as well as with the aid of the appended drawings, given as purely illustrative and informative examples in which:

• The figure 1 represents, in a schematic view, a synthetic and schematic diagram of a preferred variant of the extraction method according to the invention.

The process for extracting durum wheat germ according to the invention is a process intended to be applied to wheat masses from durum wheat varieties, the mass of cereals harvested and treated in the process according to the invention. having previously undergone treatment, no treatment or conditioning that could alter its original organoleptic qualities.

According to the invention, the mass of cereals to be treated is therefore in its native initial state close to that of the crop, the mass of cereals being in a composition close to that obtained at the end of the passage in the harvesting machine ( combine-harvester), and essentially comprising in mixture the wheat grains associated with the germ and waste, dust sounds, in different quantities, shapes and configurations. The mass of cereals to be treated is extracted from storage silos and has, for example, an average humidity of between 10 and 14%.

As shown in figure 1 a durum wheat grain is formed by a unitary unit comprising the grain or seed 1 in which the seed 2 is integrated, the grain and the seed possibly being in some cases still surrounded by a vegetable film.

The object of the invention is therefore precisely to separate or extract the seed 2 from the seed part, then to recover the seeds without these having been modified, the seed therefore remaining in an initial state close to, or even identical to, its natural state.

The figure 1 illustrates, in the form of a schematic diagram, the various essential steps of the process for extracting durum wheat germ in its natural state according to the invention.

Thus, the extraction process according to the invention is a process in which, from a harvested durum mass containing a heterogeneous mixture of grains, germs and waste or impurities of all kinds (bran, dust). , stones, strands of straw or of any kind, etc.), the separation of the seed is successively and progressively recovered, said process being carried out by a series of extraction steps exclusively mechanical and dry, without any contribution external fluid or fluid and / or without chemical processing steps in particular.

The method according to the invention therefore differs radically from the known prior art extraction of durum wheat germ, which consists precisely in using a moistening phase of the grain and the germ to precisely ensure at least their cleaning.

More specifically, the method according to the invention comprises a first step of cleaning the durum wheat mass to rid it of at least a significant part of its waste and impurities of a size similar or identical to the size of durum wheat sprouts. harvest, with a view to obtaining a cleaned durum wheat fraction.

Such a step is intended to separate, from the beginning of the extraction cycle, particles of size identical to or close to that of the wheat germ, because such a separation proves in practice extremely difficult at a later stage of the process, the germ to be separated remaining him, at this stage of the first cleaning stage, still integrated in or with the almond or the seed.

On the figure 1 a cleaning unit 3 has been indicated for the harvested durum wheat mass able to carry out this first step. The cleaning unit 3 can be formed of machines working according to different physical principles (difference in size, density, etc.), this unit being fed with Permanently by Archimedes screws connected to the storage silo (not shown).

This cleaning unit 3 may comprise at least one screening machine and a densimetric separation machine.

At this stage of the extraction process according to the invention, it is therefore ensured from the initial heterogeneous mixture of grains the separation of a cleaned hard wheat fraction 4 containing dirty durum seeds, which is thus obtained at outlet of the cleaning unit 3.

According to the invention, the extraction process then comprises a first mechanical separation step to obtain a fraction of fine products containing the seed mixed with the seeds and the residual dust or waste.

This first step of mechanical separation advantageously consists of passing the wheat mass 4 through one or more hullers 5A forming a first mechanical separation unit 5.

This unit 5 will advantageously comprise at least one 5A dehuller to ensure the mechanical separation of the seed of the kernel. Such machines are well known and include a horizontally disposed rotor on which the grain mass is directed substantially tangentially. The intensive mixing of the grain layer on the rotor makes it possible to produce a grain friction between them, a friction to the beater and a friction to the shelling coat, the refusal is directed on a suction channel.

These machines, being well known to those skilled in the art will therefore not be described in more detail.

According to the invention, the grid of the dehuller 5A will advantageously have a mesh of about 1.3 mm and will be provided with salient elements forming asperities to cause or promote tearing. Thus, according to this preferred embodiment, the horizontal huller is equipped with a grid provided with perforations of about 1.3 mm.

Of course, several horizontal dehullers can be used simultaneously in series for example or other mechanical separation units operating on similar principles that can also be used.

Thus, the first separation step is to pass the mass of durum wheat cleaned on and through a grid, to separate the seed germs by tearing and recover the fraction of fine products by passing through the mesh of the grid.

Preferably, the working face of the fixed gate will be arranged inside towards the rotor.

At the end of the first separation step, a fine product fraction 7 is obtained containing seeds in mixtures with the seeds and the dust or residual waste. Incidentally, a small fraction 6 of the cereal mass is already recovered at each unit 5A to be further processed in the extraction process according to the invention in a subsequent step forming a second mechanical separation step.

This step consists of starting from the fraction of fine products 7 to separate a fraction containing the seeds of the mass of processed cereals. The method according to the invention thus comprises a second step of separation, preferably mechanical, of the mass of fine products 7 in a fraction of grains, and a fraction of germs mixed with waste and residual dust.

This fraction of the product 7 is treated with an air recirculating tarar 8 for separating components of low specific gravity in the grain products. This equipment is of course disposed downstream of the horizontal dehuller 5A of the first mechanical separation unit 5. This second mechanical separation step is therefore preferably a densimetric separation step.

At the end of this separation, a fraction of fine products containing the seed and a recycled fraction formed essentially of wheat and thus recycled for milling are obtained.

The extraction process according to the invention is continued from the mass of fine products 10 and fraction 6 by a third mechanical separation step as illustrated in FIG. figure 1 and made in a unit 12 forming a third mechanical separation unit. This separating unit 12 preferably employs a small planichter 13 (rotostar) comprising, as is well known to those skilled in the art, a successive stack of sieves superimposed and nested one inside the other allowing from a input mass to obtain an extraction mass 15 and one or more rejection masses 14.

This step is therefore to pass the mixed seed fraction to the waste and dust on a sieve system to double sieve to recover the intermediate particle size fraction containing the seed.

In the application under consideration, the refuse mass 14 will be formed by the fraction of seeds mixed with the waste while the mass of the rejection of the extraction will be formed by seeds or other products and residual dust.

Advantageously, the planichter 13 comprises sieves of the order of 1000 microns and sieves of the order of 630 microns to recover the intermediate fraction containing the seeds (fraction between 1000 microns and 630 microns) and eliminate the other fractions.

The fraction of the reject mass 14 is stored in a silo 16 before being subjected to a final purification and separation step carried out within the installation for carrying out the extraction process by at least one unit 20 for purifying the final purification as illustrated in Figure 2, the purification unit 20 comprising at least one 20A sasseur and preferably two successive sasseurs.

The final purification step therefore consists in passing the intermediate fraction 14 corresponding to the mass of refusal to at least one sampler 20A in order to recover the clean germs, the material used being a conventional semolina sumer comprising, for example, two groups parallel formed each of three layers of horizontal sieves superposed, each layer comprising for example four sieves.

Some or all of the refusals 21 from the sasser 20A, can be recycled in the sasseur to increase the final yield of the extraction.

At the outlet of the accumulator 20A integrated in the terminal purification unit 20, the terminal fraction 22 consisting of clean durum germs is recovered, this fraction 22 then being directed to the treatment or subsequent conditioning units.

The yield of the extraction method described above makes it possible to recover between 0.1 and 0.8% of the 1.5% (on average) forming the proportion of seeds in the average weight of a grain of wheat. On average, 0.1 to 0.3% of wheat germs are recovered from the 1.5% theoretically recoverable in total weight of wheat.

The installation method according to the invention thus makes it possible to obtain a wheat germ which is naturally stabilized, since only successive mechanical operations are carried out, the mass of treated wheat and the seed contained undergoing no prior treatment in process course, especially thermal, likely to degrade its composition. The durum wheat germ thus obtained has a final composition that is identical or substantially identical to its initial composition, which enables it to retain all of its biochemical properties and to preserve in particular all of its organoleptic properties.

The durum wheat germ obtained is thus able to be stored at room temperature for several months without any noticeable change. The durum wheat germ obtained has a low starch content (less than 10%), a high protein content (greater than 35%) and a high lipid content (approximately 15%).

Claims (19)

1. Method for extracting durum wheat germ in natural state in which, from a mass of harvested durum wheat containing a heterogeneous mixture of grains, germs and waste or impurities, the germ is separated successively and progressively for recovery, said method comprising a series of exclusively mechanical extraction stages by the dry route, with no external addition of liquid.
2. Method according to claim 1, characterised in that it comprises a first step of cleaning the mass of durum wheat to remove at least a significant part of the waste and impurities of size similar to the size of the germs, and obtain a cleaned fraction of durum wheat.
3. Method according to claim 2, characterised in that from the cleaned mass of durum wheat, it comprises a first step of mechanical separation to obtain a fraction of fine products containing germs mixed with grains and dust or residual waste.
4. Method according to claim 3, characterised in that the first separation step comprises passing the cleaned mass of durum wheat over and across a grille to separate the germs from the grains by tearing and recovering the fraction of fine products by passage through the mesh of the grille.
5. Method according to claim 4, characterised in that the grille has a mesh of approximately 1.3 mm and is fitted with protruding elements forming roughnesses to cause tearing.
6. Method according to any of claims 3 to 5, characterised in that from the mass of fine products, it comprises a second step of mechanical separation of said mass into a fraction of grains and a fraction of germs mixed with the waste and residual dust.
7. Method according to claim 6, characterised in that the second step of mechanical separation is a densimetric separation step.
8. Method according to any of claims 6 or 7, characterised in that from the fraction of germs mixed with waste and dust, it comprises a third step of mechanical separation comprising passing said fraction over a double-screen sieve system to recover the fraction of intermediate granulometry which contains the germ.
9. Method according to claim 8, characterised in that the sieve system comprises a sieve of the order of 1000 µm and a sieve of the order of 630 µm to recover the intermediate fraction smaller than 1000 µm and greater than 630 µm containing the germs, and eliminate the other fractions.
10. Method according to any of claims 8 or 9, characterised in that the intermediate fraction is subjected to a final purification and separation step.
11. Method according to claim 10, characterised in that this final purification step comprises passing the intermediate fraction over at least one purifier to recover the clean germs.
12. Installation for implementation of the method extracting durum wheat germ in natural state according to any of claims 1 to 10, comprising:

    - a first cleaning unit (3) for the harvested mass of durum wheat,

    - at least a first mechanical separation unit (5) to perform the first separation step,

    - at least a second separation unit (8) to perform the second separation step,

    - at least a third mechanical separation unit (12) to perform a separation by sieving,

    - at least one purification unit (20) to perform the final purification.
13. Installation according to claim 12, characterised in that the first cleaning unit (3) comprises at least one sifting machine and one densimetric separating machine.
14. Installation according to any of claims 12 to 13, characterised in that the first separation unit (5) comprises at least one horizontal husking machine (5A) for mechanical separation of the germ from the core.
15. Installation according to claim 14, characterised in that the husking machine (5A) is fitted with a fixed grille with perforations of mesh size approximately 1.3 mm, said grille having on its surface protruding elements forming roughnesses.
16. Installation according to any of claims 12 to 15, characterised in that the second separation unit (8) comprises, after the husking machine, at least one winnowing machine with air recycling.
17. Installation according to any of claims 12 to 16, characterised in that the third separation unit (12) comprises at least one double sieve.
18. Installation according to claim 17, characterised in that the double sieve comprises a sieve of the order of 1000 µm and a sieve of the order of 630 µm.
19. Installation according to any of claims 12 to 18, characterised in that the purification unit (20) comprises at least one purifier (20A), preferably two successive purifiers.

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