EP1247579A1 - Process for extracting hard wheat germs and installation for carrying out the process - Google Patents

Abstract

The method of extracting natural hard wheat germ from a mass of grains containing a heterogeneous mixture of grains, germs and impurities comprises a first cleaning stage to eliminate a significant part of its waste and impurities having a similar size to that of the germs. From the cleaned mass a first mechanical separation stage consisting of passing the cleaned hard wheat over and through a grille is carried out to obtain a proportion of fine products containing germs mixed with grains and residual dust or waste. A second separation stage comprises a densimetric separation and is followed by a third stage of passing the fraction over a sieve to recover the graded fraction containing the germ. A final purification stage consists of passing the fraction over a purifier. An Independent claim is included for an extraction installation.

Description

The present invention relates to the general technical field of processes, installations and devices used and implemented in the food industry, and for example in flour or semolina, to extract or separate grains, products or parts of grains from harvested plants, including cereals.

The present invention relates to a method and an installation for extracting durum wheat germ in its natural state, i.e. not having undergone prior to its extraction, no operation or step of conditioning, processing or preservation, the durum wheat germ and the mass harvested cereals therefore in its physico-chemical state natural.

It is already known to carry out purification and cleaning operations of a mass of cereals formed by common wheat which is widely used widespread due in particular to its high starch content. Soft wheat presenting in its natural state a slightly brittle consistency not giving not result in natural fragmentation, it is then possible to ensure the purification and separation of the interesting food parts of a harvesting of soft wheat by proven and classic techniques. Such techniques notably use a series of smooth cylinders on which pass the common wheat harvest. The separation of common wheat from miscellaneous waste present in the harvest, as well as possible separation common wheat germs, can be easily obtained due to the tendency to crush common wheat and not to break it down, which then allows, by passing through a series of sieving devices or calibration, to ensure the separation of the various ingredients.

Classic purification, cleaning and separation techniques used for common wheat are not applicable to crops and seeds of plants with hardness and resistance characteristics superior mechanical, mainly due to their tendency natural to fragmentation into many particles. These characteristics complicate the extraction and cleaning processes of such vegetable seeds if one wishes to preserve the physical integrity and physiological of the seed which one wishes to separate, or of fragments of seeds that we also want to separate.

This is the reason why the techniques known to date in terms of of undifferentiated germs or fractions from durum wheat all involve a preconditioning of durum wheat, namely a phase humidification, specifically to try to resolve the natural tendency to fragment durum wheat. So a technique known extraction from durum wheat consists, after dry cleaning of the mass to be treated, to condition the mass to be treated with a supply of water preceding a stage of transformation and separation of wheat, germ and waste through a series of successive stages including grinding, sieving and purification or sassage.

This known extraction technique gives acceptable results, but nevertheless suffers from various disadvantages. So it turns out that the need to use a pre-humidification of the grain implies necessarily at the end of the extraction process obtaining products with relatively high humidity, which prevents good conservation of the final product. This is the reason why this technique previous requires the addition of an additional heat treatment at the end of treatment. Obviously, the heat treatment an additional cost to the process, which constitutes a handicap on the industrial level. Furthermore, the treatment in general is inevitably accompanied by a transformation of the taste of the product obtained, or particular organoleptic qualities resulting from the addition of heat (especially toasted taste).

It also turns out that the known prior art operating by way of wet is not able to provide an overall process yield sufficient extraction, since it allows only a tiny fraction to be recovered wheat germs present in the treated mass, precisely because operating conditions linked to the chosen wet process.

Finally, and in the event that the final heat treatment is insufficient, we note then the appearance of rancidity phenomena of the wheat germ obtained, linked precisely to the inadequacy of the final heat treatment.

The object of the invention therefore aims to remedy the various disadvantages listed above, and to propose a new process and a new germ extraction facility that provides durum wheat germ of which all the initial organoleptic qualities are preserved, while being simple and easy to implement on the plan industrial.

Another object of the invention is to propose a new method and a new extraction facility that can supply using simple means an acceptable yield from 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 can be used without notable modification of conventional separation and cleaning units in the field.

The objects assigned to the invention are achieved using a process extraction in its natural state of the durum wheat germ in which, from of a mass of harvested cereals containing a heterogeneous mixture of grains, germs and waste or impurities, successively and gradually separating the germ to recover it, said process being produced by a series of exclusively mechanical extraction steps and by dry process, 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 implementing the process for extracting, in its natural state, the durum wheat germ according to one of claims 1 to 10 comprising:

• a first unit for cleaning the mass of durum wheat harvested,
• at least a first mechanical separation unit for carrying out the first separation step,
• at least a second separation unit for carrying out the second separation step,
• at least one sieving unit for carrying out the sieving step,
• at least one purification unit to carry 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 by way of purely illustrative and informative examples in which:

• Figure 1 shows, in a schematic view, a synthetic and schematic diagram of a preferred variant of the extraction process according to the invention.

The process for extracting the durum wheat germ according to the invention is a process to be applied to masses of wheat from varieties durum wheat, the mass of grain harvested and processed in the process according to the invention having prior to its treatment undergone absolutely no treatment or conditioning likely to modify its initial organoleptic qualities.

According to the invention, the mass of cereals to be treated is therefore in its state initial native close to that of the harvest, the mass of cereals being in a composition close to that obtained after passing through the machine of harvest (combine), and comprising mainly in mixes the wheat grains associated with the germ and waste, dust sounds, in different quantity, shape and configuration. The mass of cereals to process is extracted from storage silos and presents for example a average humidity between 10 and 14%.

As shown in Figure 1, a grain of durum wheat is formed by a set unit comprising the grain or the seed 1 within which the germ 2 is integrated, the grain and the seed possibly still being in certain cases surrounded by vegetable wrap.

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

Figure 1 illustrates, in the form of a schematic diagram, the different essential stages of the durum wheat germ extraction process in its natural state according to the invention.

Thus, the extraction process according to the invention is a process in which, from a mass of durum wheat harvested and containing a mixture heterogeneous of grains, germs and waste or impurities of all kinds (bran, dust, stones, straw or any kind of straw, etc.), we ensure successively and gradually the separation of the germ for the recover, said process being carried out by a series of extraction steps exclusively mechanical and dry, without external supply of liquid or fluid and / or without chemical treatment steps in particular.

The process according to the invention therefore differs radically from the technique known anterior extraction of durum wheat germ, which consists precisely to use a grain and germ humidification phase to precisely ensure at least their cleaning.

More specifically, the method according to the invention comprises a first step cleaning the mass of durum wheat to rid it of at least one significant part of its waste and impurities of similar or identical size the size of the durum wheat germ to be harvested, in order to obtain a fraction of durum wheat cleaned.

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

In FIG. 1, a cleaning unit 3 of the durum wheat mass has been indicated. harvested able to perform this first step. Cleaning unit 3 can be made up of machines working according to different physical principles (difference in sizes, density, ...), this unit being supplied with permanently by Archimedes screws connected to the storage silo (not represented).

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

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

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

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

This unit 5 will advantageously include at least one huller 5A to ensure the mechanical separation of the germ from the kernel. Such machines are well known and include a rotor arranged horizontally on which the mass of cereals is directed substantially tangentially. Intensive mixing of the cereal layer on the rotor allows to produce a friction of the grains between them, a friction to the beater and a friction to the shelling coat, the refusal is directed on a channel suction.

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

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

Obviously, several horizontal hullers can be used simultaneously in series for example or other units of mechanical separation operating on similar principles which can be also used.

So the first separation step is to pass the mass of durum wheat cleaned on and through a rack, to separate germs from grains by uprooting and recovering the fraction of fine products by passage through the grid mesh.

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

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

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

This fraction of the product 7 is treated by an air recycling port 8 to separate components of low specific gravity in the grain products. This equipment is obviously placed downstream of the horizontal sheller 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 is obtained 10 containing the germ and a recycled fraction 11 formed essentially by wheat and therefore recycled for milling.

The extraction process according to the invention continues from the mass of fine products 10 and fraction 6 by a third step of mechanical separation as illustrated in figure 1 and carried out in a unit 12 forming a third mechanical separation unit. This unit of separation 12 preferably uses a small plansichter 13 (rotostar) comprising as is well known to those skilled in the art, a battery successive of superimposed sieves and nested in each other allowing from an input mass to obtain an extraction mass 15 and one or more refusal masses 14.

This step therefore consists in passing the fraction of germs mixed with waste and dust on a double sieve sieve system for recover the intermediate particle size fraction containing the germ.

In the application considered, the refusal mass 14 will be formed by the fraction of germs mixed with waste while the mass of the refusal to the extraction 15 will be formed by seeds or other products and residual dust.

Advantageously, the plansichter 13 comprises sieves of the order of 1000 µm and sieves of the order of 630 µm to recover the fraction intermediate containing the germs (fraction between 1000 µm and 630 µm) and eliminate the other fractions.

The fraction of the refuse mass 14 is stored in a silo 16 before being subject to a final stage of purification and separation carried out within of the installation for implementing the extraction process by at least one purification unit 20 making it possible to carry out the final purification as illustrated in the FIG. 2, the purification unit 20 comprising at least one sander 20A and preferably two successive sasseurs.

The final purification step therefore consists in passing the fraction intermediate 14 corresponding to the mass of refusal on at least one sasser 20A to recover clean germs, the material used can be a classic semolina sander consisting for example of two groups parallel formed each of three layers of superimposed horizontal screens, each layer comprising for example four sieves.

Part or even all of the refusals 21 from the sander 20A can be recycled in the sasser to increase the final yield of extraction.

At the outlet of the sander 20A integrated in the terminal purification unit 20, there is recovers the terminal fraction 22 consisting of clean durum wheat germs, this fraction 22 then being directed to the processing or subsequent conditioning.

The yield of the extraction process described above allows recover between 0.1 and 0.8% among the 1.5% (on average) forming the proportion of germs in the average weight of a grain of wheat. On average, we recover between 0.1 and 0.3% of wheat germs among the 1.5% theoretically recoverable by 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 operations successive mechanicals are used, the mass of wheat treated and the germ contained not undergoing any prior treatment during process, in particular thermal, likely to degrade its composition. The durum wheat germ thus obtained has an identical final composition or substantially identical to its initial composition, which allows it to keep all of its biochemical properties and keep in particular all of its organoleptic properties.

The durum wheat germ obtained can thus be stored at temperature ambient for several months without significant modification. Wheat germ hard obtained has a low starch content (less than 10%), a high protein content (over 35%) and a high lipid content (about 15%).

Claims (19)

Process for the extraction, in its natural state, of the durum wheat germ in which, from a mass of harvested cereals containing a mixture heterogeneous grains, germs and waste or impurities, we ensure successively and gradually the separation of the germ for the recover, said process being carried out by a series of extraction steps exclusively mechanical and dry, without external input of liquid. Process according to Claim 1, characterized in that it comprises a first step of cleaning the mass of durum wheat, to rid it of at least a significant portion of its waste and impurities of size similar to the size of the germs, and obtaining a fraction of durum wheat cleaned. Process according to Claim 2, characterized in that, starting from the mass of durum wheat cleaned, it comprises a first step of mechanical separation, in order to obtain a fraction of fine products containing the germs in mixture with the seeds and the residual dust or waste . A method according to claim 3 characterized in that the first separation step consists in passing the mass of cleaned durum wheat over and through a grid, to separate the germs from the grains by pulling out and recover the fraction of fine products by passing through the grid meshes. A method according to claim 4 characterized in that the grid has a mesh of about 1.3 mm and is provided with projecting elements forming asperities to cause tearing. Method according to one of claims 3 to 5 characterized in that, starting 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. A method according to claim 6 characterized in that the second mechanical separation step is a densimetric separation step. Method according to either of Claims 6 and 7, characterized in that, starting from the fraction of germs mixed with waste and dust, it comprises a third step of mechanical separation which consists in passing said fraction over a double sieve system sieving to recover the intermediate particle size fraction containing the germ. Process according to Claim 8, characterized in that the sieve system comprises a sieve of the order of 1000 µm and a sieve of the order of 630 µm for recovering the intermediate fraction less than 1000 µm and more than 630 µm containing germs, and eliminate other fractions. Method according to one of claims 8 or 9 characterized in that the intermediate fraction is subjected to a terminal stage of purification and separation. Process according to Claim 10, characterized in that this final purification step consists in passing the intermediate fraction over at least one sassifier, to recover the clean germs. Installation for carrying out the extraction process in its natural state of the durum wheat germ according to one of claims 1 to 10 comprising: a first cleaning unit (3) for the mass of durum wheat harvested, at least a first mechanical separation unit (5) for carrying out the first separation step, at least a second separation unit (8) for carrying out the second separation step, at least a third mechanical separation unit (12) for carrying out a screening separation, at least one purification unit (20) for carrying out the terminal purification. Installation according to claim 12 characterized in that the first cleaning unit (3) comprises at least one screening machine and a densimetric separation machine. Installation according to one of claims 11 to 13 characterized in that the first separation unit (5) comprises at least one horizontal huller (5A), to ensure the mechanical separation of the germ from the kernel. Installation according to claim 14 characterized in that the huller (5A) is equipped with a fixed grid provided with perforations meshed to approximately 1.3 mm, said grid being provided on its surface with projecting elements forming asperities. Installation according to one of claims 12 to 15 characterized in that the second separation unit (8) comprises, downstream of the huller, at least one air recirculation valve. Installation according to one of claims 11 to 16 characterized in that the third separation unit (12) comprises at least a double screen. Installation according to claim 17 characterized in that the double screen comprises a screen of the order of 1000 µm and a screen of the order of 630 µm. Installation according to one of claims 11 to 18 characterized in that the purification unit (20) comprises at least one sapper (20A), and preferably two successive sappers.

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