DE102012107962B4 - Cereal peeling machine, process for refining grain and its use for reducing pollutants - Google Patents

Abstract

A cereal peeling machine, comprising a vertically arranged container for receiving the grain to be peeled, which has a filler neck and an outlet on the underside, wherein in the container interlocking engagement elements are movable past each other, which forms a gap between the engagement elements when moving past each other, so that a shear stress can be exerted on the cereal grains to be husked and wherein the cereal peeling machine has a plurality of planes arranged one above the other with engaging elements.

Description

Field of the invention

The invention relates to a cereal peeling machine, in particular for wheat, and to a process for refining cereals. Furthermore, the invention relates to the use of a method for finishing grain to reduce pollutants.

Background of the invention

For cereals, especially wheat, a distinction is usually made between products in which shell components have been removed and whole-grain products.

When removing the shell, which is usually removed in conventional mills only when grinding, on the one hand valuable vitamins and minerals are lost, which are lost under the shell or in a lowermost shell layer, the aleurone layer. Also, in conventional grinding processes, some of the starch present in the meal body is lost in separating shell components and starch components.

Further, whole grain products can be used especially in the bread making, in which the grain is not peeled. In addition to other properties in terms of color and taste is in whole grains of disadvantage that may be located in particular in the outer layers of the shell harmful substances such as spillage residues or fungal spores, which are usually not removed when cleaning the whole grain.

Further, in a conventional milling process, the aleurone layer of the grain, which is very rich in vitamins and minerals, is largely removed along with the bran.

Especially relevant are mycotoxins of the fungus Fusarium, a natural soil fungus, which, in addition to other microorganisms, is basically responsible for the degradation of plant residues.

A particularly relevant mycotoxin is desoxynivalenol (DON). The limit values for DON are currently between 200 μg / kg (diet food and baby food) and 500 μg / kg (grains processed for direct consumption).

Already with the harvest, the grain is considered as a food and would have in the following, d. H. during storage and further processing, continuously checked for fungal attacks.

It is also questionable how existing mycotoxins act on flour, which is produced from the contaminated grain. In the conventional milling process existing shell components are mainly removed as bran.

Further known from practice is the optical sorting of the pre-cleaned grain.

The documents DE 22 994 A and GB 557 228 A show grain peeling machines with rotor and stator elements. The document GB 392 234 A provides hints to soak the grain before peeling.

Object of the invention

It is an object of the invention to provide a simple and reliable grain peeling machine, which enables a high throughput despite its compact design and is suitable for industrial use.

Summary of the invention

The object of the invention is already achieved by cereal peeling machine according to claim 1.

Preferred embodiments and further developments of the invention can be found in the subclaims.

The invention relates to a cereal peeling machine. This is intended in particular for peeling wheat and durum wheat. The grain peeling machine comprises a container for receiving the grain to be peeled.

Preferably, the grain peeling machine is operated continuously, that is, the container comprises at least one inlet through which the grain enters the container and at least one outlet from which the peeled grains and peel components emerge.

It is understood that peeling in the sense of the invention does not necessarily mean the complete separation of all shell layers of the cereal grain. Rather, it is provided in particular that predominantly only the outer layers of the shell are separated, behind which are mainly the harmful substances mentioned above.

The container may be formed, for example, as a cylinder, in particular as a circular cylinder. Preferably, the grains move due to their own gravity through the container, so are embedded in an upper region and leave in the peeled state in a lower region of the container.

For peeling the cereal crop, the container comprises interlocking engagement elements, which are movable past each other, so that when moving past each other forms a gap between the engagement elements.

The engagement elements may be designed in particular as a rotor and stature elements.

Under engagement elements are rigid components, in particular designed as rods understood that are moved past each other at a small distance.

For example, the engagement elements may be metal rods, in particular stainless steel. These have a long life, are easy to clean and do not give harmful substances to the material to be peeled off. It is also conceivable, however, to provide the engagement elements with a coating, in particular a hydrophobic coating, in order to reduce the adhesion of cereals and shell constituents.

For moving past the engagement elements in particular a rotor / stator arrangement is suitable, in which at least one rotor, on which engagement elements are arranged, is set in a rotational movement, so that the engagement elements move relative to the stator. Since it only depends on a relative movement against each other, it is also conceivable to put the "stator" in a rotational movement, preferably in opposite directions to the rotor.

Instead of a rotational movement is also conceivable to move the engagement elements in a linear movement past each other.

If the engagement elements are designed as rods, in particular a round shape has proven to be particularly suitable. For example, the grain peeling machine may include a rotor with radially outwardly facing rods, the housing which is part of the stator also having rod-shaped engagement elements pointing radially inward toward the central axis of the rotor.

When moving the engagement elements against each other creates a gap whose minimum width is defined by the fact that the engagement elements are directly opposite. The minimum width should be greater than the diameter of the grains to be peeled. Preferably, the minimum width of the gap between the engagement elements is between 1 and 20 millimeters, preferably between 3 and 8 millimeters.

The inventors have found that shear forces can be exerted on the cereal grains to be peeled over such engaging elements moving past each other. According to the principle of shear, the grain shell is deformed so that it tears open and is at least partially separated.

Surprisingly, it has been found that even with a relatively small number of engagement elements, a very high throughput of grain to be peeled is made possible. The inventors suspect that this surprising effect is due to the fact that not only those directly from the Grains are subjected to shear stress, but that by moving the grains together, this effect continues from grain to grain.

When peeling, preferably such a large amount of grain is added to the container that it is at least partially filled with bulk material. The grains are thus directly adjacent to each other, the engagement elements are moved with a fairly high force required by the container. So it is possible to achieve a very high throughput already with a relatively small machine.

In one embodiment of the invention, the grain peeling machine has a plurality of superimposed planes with engagement elements.

In particular, a grain peeling machine is provided which has between two and thirty, preferably between three and eight rows, each with corresponding rotor and stator elements.

A single plane, in which in particular the rotor and stator elements formed as rods are arranged in a star shape, can each have 3 to 20, preferably 5 to 10, rotor or stator elements.

The container may comprise a substantially vertically disposed circular cylinder, which preferably has a diameter between 10 and 100 cm, more preferably between 20 and 40 cm. Already with such a small plant can peel several tons of wheat per hour.

It is particularly advantageous that the machine according to the invention is scalable in terms of size for the respective application.

In a preferred embodiment, the cereal peeling machine has a modular structure and comprises a module for moistening, in particular for dipping the cereal, a module in which the cereal grains are peeled, and a module with which peeled cereal grains and peel constituents are separated from one another. Furthermore, a module for feeding the grain and / or a module for packaging the grain may be provided.

In a further development of the invention, air can be injected into the container. By blowing in air, the adhesion of shell residues, in particular on the container wall, can be reduced. Furthermore, when previously moistened grain is used, it is already dried during the grinding process. Due to the energy input by the peeling process, as well as the injected air, it is even possible that the grain has such a low residual moisture after the peeling process that can be dispensed with a further elaborate drying.

The air can be blown in particular by means distributed around the periphery of the container nozzles. But it is also conceivable to blow the air against the direction in which the grain is transported.

In a further preferred embodiment of the invention, an area for moistening the grain is arranged in front of the container. In this area, the shell can be brought to a moisture content of 30 to 40%, so that it can be easily removed afterwards.

The moistening area may for example consist of a route within which the grain grains conveyed to the inlet of the container are submerged in water. For example, a screw conveyor can be used for this purpose.

The invention further relates to a method for peeling cereals by means of a machine as described above.

According to the method, the cereal grains in a cereal peeling machine are subjected to shear stress by means of mutually moving rigid engaging elements between which a gap is formed.

Preferably, cereal grains are soaked in water before being peeled.

When peeling is in a preferred embodiment of the invention in the container of the grain peeling machine, in which the engagement elements are arranged such a large amount of grain filled that the cereal grains at least partially as bulk material with a bulk density of 0.3 kilograms per liter, preferably size 0, 5 kilograms per liter, present. In contrast to peeling processes in which the grains are catapulted against a wall, for example by means of a brush, the grains are present as dense bulk material. As already described above, it has been found that in a surprisingly simple manner, a high energy can be introduced into this bulk material and a good peeling result is achieved at very high throughput. This is presumably also due to the fact that shear forces are exerted on the material to be peeled in a large range by the alternately arranged, respectively counter-rotating engagement elements, for example designed as a rotor or stator, which preferably overlap at least eighty percent of their length.

In the event that the engagement elements are partially formed as rotor elements, the grain peeling machine is preferably at a peripheral speed between 0.1 and 10 m / s, preferably between 0.5 and 5 m / s, and more preferably between 1 and 2 m / s emotional. The peripheral speed is understood to mean the speed at the outermost point of the rotor elements.

It has thus been found that in the peeling method according to the invention, relatively low speeds of movement of the engagement elements are optimal. This is because the grains are not peeled mainly by an impact on the engaging elements, but due to the existing shear forces.

In a preferred embodiment of the invention, the grains to be peeled are conveyed by gravity through the machine. An inlet, through which the grains enter the working space of the peeling machine, is thus at an upper position and an outlet at a lower position.

Alternatively, it is also conceivable to convey the grains by blowing by means of compressed air or other media or by means of a screw through the working space of the grain peeling machine.

In a development of the invention, the grain peeling machine is designed to be mobile. For this purpose, the grain peeling machine can be part of a mobile machine in particular. This allows the grain in the processing chain to be peeled at a very early stage.

So it is conceivable that the grain is peeled immediately after the harvest, so before storage steps in a silo. Existing fungal spores and pollutants are removed at a very early stage in the processing chain so that, especially in the case of harmful microorganisms such as fungi, retransmission is stopped at a very early stage.

In general, it is conceivable to use the cereal peeling machine according to the invention at any point in the processing chain.

The grain peeling machine is doing the high performance at the same time compact dimensions to good.

The intensity of the peeling process, in particular the amount of shells removed, can be controlled system-specifically by the residence time. For this purpose, the peeling machine preferably comprises a throttle device at the outlet.

In a preferred embodiment, one to ten percent, preferably four to five percent, of the total weight of the grains is removed as a shell. It is provided in particular that only the upper shell layers are removed, while the underlying aleurone layer is predominantly preserved.

To separate shell and peeled grain from each other, it is particularly provided that after passing through the container trays and peeled grains are separated by a fan.

In particular, the grain peeling machine may comprise a fan, in particular a radial fan, which is arranged below an outlet. The light shell components can be separated in a very simple and effective way from the heavier peeled grains. The advantage is further that a further drying of the grain is made.

The invention further relates to the use of the process of refining grain, in which the cereal grains are soaked in water, in particular by immersion or immersion, and then the shell is removed frictionally to reduce the burden of the grain on pollutants.

The invention is based on the finding that a soaking the cereal grains in water and subsequent frictional, so caused by friction separation of the shell, in a very simple manner, a product can be produced in which for a minerals and vitamins largely retained, but at the same time In a surprisingly significant way mycotoxins, but also other pollutants such as heavy metals and spray residues, can be effectively removed.

For frictional separation of the shell, in particular a grain peeling machine can be used, as will be described in detail below.

Preferably, the corn is dipped in water for a period of two to twenty minutes, and then the shell is removed frictionally.

In particular, the burden of deoxynivanenol can be reduced. In particular, the load is reduced by at least 80%.

The results of an exemplary method according to the invention are shown in the following table.

It can be seen that, in particular, the burden of DON is reduced below the detection limit, whereas the minerals remain unchanged.

Extremely surprising is also the fact that the germination of the grain is not reduced, but according to the table after the above investigation even improved.

This is due to the fact that the strength of the meal body and the endosperm are less damaged by the inventive use of the grain refining process.

Ideally, a cereal product is made comprising an endosperm that is predominantly covered by aleurone layer, the shell otherwise being separated.

Valuable vitamins and mineral constituents of the aleurone layer are retained, at the same time a substantially undamaged grain with a smooth shell, since only the fruit peel was removed. In particular, at least 50%, preferably at least 80%, of the surface is covered with an aleurone layer.

In a preferred embodiment of the invention, the cereal grains are packed immediately after refining, in particular peeling. This is possible because pollutants have already been removed at this stage

It has been found that despite the soaking with water due to the frictional process, the residual moisture content is so low that the grains tend not to be attacked by fungi.

The cereal product produced according to the invention can serve as starting material for other products, in particular baking and pasta, starch and flour, as dietary supplements, etc.

The preparation is simple and economical and it eliminates in particular the wetting in practice of the grains in conventional mills over a longer period of 18 to 24 hours.

Furthermore, discoloration of the cereal product is generally removed with the skin in such a way that, depending on the further processing, a more beautiful yellowing of the product is possible, this applies in particular to semolina.

The method is suitable in principle for all cereals, especially hard and soft wheat. Preferably, the method is used for durum wheat, in which the problems with Fusarium infestation in particular are usually the largest.

Furthermore, as provided in a preferred embodiment of the invention, the cereal product can be used to form flakes, in particular for cereals, bread products or granola bars.

Due to the high purity of the precursor can usually be dispensed with in the practice of heat treatment of the flakes usually performed today in practice, by which vitamins are lost on a large scale, as a rule.

As a further use is particularly provided to use the shell components for the production of bioethanol.

Furthermore, as is shown in a further development of the invention, the grain in which the aleurone layer is still present can be further processed, for example by grinding, so that the aleurone layer is separated from the endosperm. This can be done in particular in a subsequent processing step.

Thus, it is possible for the first time to remove the aleurone layer separately from other shell components.

In particular, the aleurone layer can now be used for the production of cosmetics, dietary supplements and pharmaceuticals.

The invention enables a novel process control, in which the grain is refined immediately after harvesting. Consequently, the unpeeled cereal grains are not stored for a long time in a silo, but are peeled immediately after harvesting and stored in the refined, ie cleaned and peeled state.

Since mushrooms already present on the trays are already predominantly removed at this time, there is much less danger that the grain will continue to be infested with fungi during the subsequent storage.

Description of the drawings

The invention will be described below with reference to a in the drawings 1 to 6 schematically illustrated embodiment will be explained in more detail.

1 shows a perspective view of a cereal peeling machine ( 1 ).

The cereal peeling machine ( 1 ) comprises a container ( 2 ) for receiving the grains to be peeled. These can be filled via a filler neck ( 3 ) the container ( 2 ). In the container ( 2 ) Interlocking rotor and stator elements (not shown) are provided, over which the grain is peeled. On the outside ( 2 ) of the container holding sleeves for the stator elements can be seen in this embodiment, which may optionally be waived. Thus, in particular, the stator elements integral with the container ( 2 ), in particular be welded to this.

The material to be husked is moved by gravity through the container ( 2 ) and exits at an outlet on the bottom (not visible).

The one in the container ( 2 ) existing rotor (not visible) is via a pulley ( 4 ).

The drive is an engine ( 5 ), which although the container ( 2 ) only has a diameter of twenty to forty centimeters, has a power of several kW. Through various pulleys (The belts are not shown in this illustration) a translation is provided, so that in particular the stator can be operated at a fairly low speed of 20 to 150 revolutions min ^-1 .

About the slider ( 14 ), as will be shown in detail below, the residence time of the material to be peeled are adjusted.

2 shows a sectional view of the in 1 represented container ( 2 ). To recognize are those of the jacket of the container ( 2 ) Statorelemente projecting into the working space ( 9 ). Corresponding rotor elements ( 8th ) are on a rotor shaft ( 7 ) attached. The rotor elements ( 8th ) protrude in a star shape from the rotor shaft ( 7 ).

The rotor shaft ( 7 ) has at least 0.25, preferably at least 0.3 times the diameter of the inner diameter of the container ( 2 ). This avoids that in the vicinity of the rotor shaft, the peripheral speed of the rotor elements is very low. Furthermore, the forces acting on the rotor elements ( 8th ) act, be minimized.

Both rotor elements ( 8th ) as well as stator elements ( 9 ) are formed in this embodiment as rods, in particular with a diameter between 0.5 and 3 cm. It has been shown that especially round or at least rounded rods are suitable. The use of angular contours can increasingly lead to undesirable fractures of the individual cereal grains.

The stator elements are preferably designed to be exchangeable, for example by holding them in sleeves.

It is also conceivable to use differently shaped stator elements, for example with different profiles and / or different diameters.

Thus, the cereal peeling machine can be easily adapted to different cereals.

3 shows a sectional view of the in 1 shown container in the axial direction.

It can be seen that rotor elements ( 8th ) and stator elements ( 9 ) are arranged in rows in each other. Passing the rotor elements past each other ( 8th ) relative to the stator elements ( 9 ) column ( 19 ) of thickness d. As a result, shear forces are transferred to the material to be peeled.

The peeling machine shown here has a total of nine pairs of superimposed rotor and stator elements.

At least the stator elements ( 9 ) can be removed in this embodiment. It has been found that in this embodiment of a grain peeling machine already five corresponding rotor / stator elements achieve a good peeling result. It is understood that the expert will adapt the number of rotor and stator elements plant specific and specific to the material to be ground.

4 shows a perspective view of the grain peeling machine, wherein in this view, the container comprising the stator elements is hidden.

To recognize now is the rotor ( 6 ) with nine superimposed rotor elements ( 8th ). The over the filler neck ( 3 ) filled to be peeled Good is transported by its own gravity continuously down. Below the rotor is a conveyor ( 10 ), which with the rotor ( 6 ) and plate-shaped slide comprises, the peeled cereal material to an outlet ( 11 ).

Details of this conveyor will be referred to the perspective view in FIG 5 explained. In 5 the rotor is hidden. Evident is the arranged on a lower plate of the grain peeling conveyor ( 10 ). Between conveyor and the hidden rotor is an intermediate plate ( 12 ) is introduced into the container, which has a passage ( 13 ). Through the passage ( 13 ) the peeled good can be used by the conveyor ( 10 ). For this purpose, the passage ( 13 ) with a movable slide ( 14 ), over which the cross-section of the passage ( 13 ) can be reduced. About the slider ( 14 ), so the residence time of the material to be peeled in the container can be regulated in a very simple manner.

The peeling process will be described below with reference to the schematic sectional view in 6 be explained in more detail. The grain to be husked, in particular wheat kernels to be husked, is first soaked in water (not shown) and then via the inlet nozzle ( 3 ) fed to the grain peeling machine. In the workroom ( 15 ) of the cereal peeling machine is a rotor ( 6 ) provided with rotor elements which on projecting out of the wall of the housing stator elements ( 9 ). By gravity, the grain to be husked moves downwards and can pass through the passage ( 13 ) an intermediate plate ( 12 ) the working space ( 15 ), wherein the residence time through the slide ( 14 ) can be adjusted. About the previously described conveyor ( 10 ) the peeled good is an outlet ( 11 ) and exits the housing. Below the outlet ( 11 ) is a radial fan ( 16 ) are provided, over which the peeled grains are separated from the shell remnants. In this embodiment, via the radial fan ( 16 ) the shell components to the shell outlet ( 18 ), while the heavier husked cereal grains over the other spout ( 17 ) Leave the machine and now either collected and packaged or further processing steps can be supplied.

With the invention, a very simple, robust and compact peeling machine could be provided by means of which very high throughputs can be realized.

LIST OF REFERENCE NUMBERS

1

Corn peeling machine

2

container

3

filler pipe

4

pulley

5

engine

6

rotor

7

rotor shaft

8th

rotor member

9

stator

10

promoter

11

outlet

12

intermediate plate

13

passage

14

pusher

15

working space

16

centrifugal blower

17

grain outlet

18

shell outlet

19

gap

Claims (19)

A cereal peeling machine, comprising a vertically arranged container for receiving the grain to be peeled, which has a filler neck and an outlet on the underside, wherein in the container interlocking engagement elements are movable past each other, which forms a gap between the engagement elements when moving past each other, so that a shear stress can be exerted on the cereal grains to be husked and wherein the cereal peeling machine has a plurality of planes arranged one above the other with engaging elements. Cereal peeling machine according to the preceding claim, characterized in that the engagement elements are designed as rotor elements and stator elements. Cereal peeling machine according to one of the preceding claims, characterized in that a minimum width of the gap between the engagement elements between 1 and 20 mm, preferably between 3 and 8 mm. Cereal peeling machine according to one of the preceding claims, characterized in that the engagement elements are formed as extending through the container rods, in particular as radially extending through the container rotor and / or stator elements. Cereal peeling machine according to one of the preceding claims, characterized in that the grain peeling machine has between 2 and 30, preferably between 3 and 8 rows with rotor and stator elements. Cereal peeling machine according to one of the preceding claims, characterized in that the grain peeling machine has planes with 3 to 20, preferably 5 to 10, rotor and / or stator elements. Cereal peeling machine according to one of the preceding claims, characterized in that the container comprises a substantially vertically arranged circular cylinder, in particular with a diameter between 10 and 100 cm, preferably 20 and 40 cm. Cereal peeling machine according to one of the preceding claims, characterized in that air can be injected into the container, in particular by means of nozzles distributed around the circumference of the container. Cereal peeling machine according to one of the preceding claims, characterized in that an area for moistening the cereal is arranged in front of the container. A method of refining grain with a grain peeling machine according to any one of the preceding claims, wherein the cereal grains are moistened and subjected to shear stress in a cereal peeling machine by means of mutually moving engaging elements between which a gap is formed, and wherein the moistened cereal grains are gravity fed through a vertical arranged container in which the engagement elements are arranged, are conveyed and emerge at an outlet on the underside of the container, and wherein the container is filled with such a large amount of grain, that the container is at least partially filled with bulk material. Process for refining cereals according to claim 10, characterized in that the cereal grains are at least partially present as bulk material with a bulk density greater than 0.3 kg / l, preferably greater than 0.5 kg / l. Process for refining cereals according to one of claims 10 or 11, characterized in that the engagement elements are partially formed as rotor elements and with a peripheral speed between 0.1 and 10 m / s, preferably between 0.5 and 5 m / s and especially preferably be moved between 0.8 and 1.6 m / s. Process for refining cereals according to one of claims 10 to 12, characterized in that the grains pass through the container by their gravity and, after passing through the container, trays and peeled grains are separated from one another by a fan. Use of a method of refining cereals according to any one of claims 10 to 13 wherein the cereal grains are soaked in water and then the shell is removed frictionally to reduce the burden of the grain on pollutants, whereby the grain is peeled prior to storage in a silo. Use of a method according to claim 14, characterized in that the burden of mycotoxins, in particular the burden of deoxynivalenol is reduced. Use of a method according to one of claims 14 or 15, characterized in that after refining the cereal in a further process step aleurone layer and endosperm are separated from each other. Use of a method according to any one of claims 14 to 16, characterized in that the grain is ground after refining or is processed into flakes. A cereal product obtainable by a process according to any one of claims 10 or 11, wherein the cereal product is formed as an endosperm with an existing aleurone layer but with an otherwise removed shell. A cereal product according to claim 18, characterized in that the cereal product comprises grains or their processing products consisting of an endosperm covered at least 50%, preferably at least 80%, of its surface with an aleurone layer.

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