Method For Conditioning Plant Seeds For Milling, In Particular For Influencing The Elasticity Of The Plant Seeds, And System For milling Plant Seeds

Abstract

The present invention relates to a method for conditioning plant seeds (3) for disintegration and to a system (1) for disintegration of plant seeds (3), comprising a conditioning system (2) for conditioning the plant seeds (3), a disintegration device (4) for disintegration of the conditioned plant seeds (3), and a separating device (5) for separating different fractions of the disintegrated plant seeds. In order to provide a method and a device which facilitate the subsequent disintegration of the plant seeds and positively influence the behavior of the plant seeds during the disintegration process, according to the invention, the plant seeds (3) are exposed to an electrical field, or the conditioning system (2) has a capacitor (6) for generating an electrical field that acts on the plant seeds (3).

Claims

1. Method for conditioning plant seeds (3) for disintegration, in particular for influencing the elasticity of the plant seeds (3), characterized in that the plant seeds (3) are exposed to an electrical field.

2. Method according to claim 1, wherein the plant seeds (3) are electroporated by means of the electrical field.

3. Method according to claim 1, wherein in the treatment with the electrical field, an energy input of 1 kJ/kg to 20 kJ/kg, preferably of 8 kJ/kg to 12 kJ/kg, into the plant seeds (3) is accomplished.

4. Method according to claim 1, wherein the plant seeds (3) are exposed to an electrical field strength of 0.3 kV/cm to 10 kV/cm, preferably of 2 kV/cm to 4 kV/cm.

5. Method according to claim 1, wherein the plant seeds (3) are exposed to a pulsed electrical field.

6. Method according claim 1, wherein the elasticity of the plant seeds (3) is improved during conditioning compared to non-conditioned plant seeds.

7. Method according to claim 6, wherein the elasticity of the seed coat and/or the elasticity of the seed kernel, in particular the endosperm, is modified during conditioning.

8. Method according to claim 1, wherein a moistening liquid (18) is added to the plant seeds (3) before or while they are exposed to the electrical field.

9. Method according to claim 1, wherein the plant seeds (3) are exposed to a predetermined pressure and/or a predetermined temperature.

10. Method according to claim 1, wherein enzymes act on components of the plant seeds (3).

11. Method according to claim 10, wherein the enzymes are selected from the group of hemi-cellulases, cellulases, glucanases, laccases, proteases und amylases.

12. System (1) for disintegration of plant seeds (3), comprising a conditioning system (2) for conditioning the plant seeds (3), a disintegration device (4) for disintegration of the conditioned plant seeds (3), and a separating device (5) for separating different fractions of the disintegrated plant seeds, wherein the conditioning system (2) has a capacitor (6) for generating an electrical field that acts on the plant seeds (3).

13. System (1) according to claim 12, wherein the conditioning system (2) has a wetting device (14) for moistening the plant seeds (3) and/or a tempering cell (7).

14. System (1) according to claim 12, wherein the conditioning system (2) has a temperature and/or pressure controller (19).

15. System (1) according to claim 12, wherein the capacitor (6) comprises at least two electrodes (9) which are connected to a pulse generator as a voltage source (11).

16. Method according to claim 2, wherein in the treatment with the electrical field, an energy input of 1 kJ/kg to 20 kJ/kg, preferably of 8 kJ/kg to 12 kJ/kg, into the plant seeds (3) is accomplished.

17. Method according to claim 2, wherein the plant seeds (3) are exposed to an electrical field strength of 0.3 kV/cm to 10 kV/cm, preferably of 2 kV/cm to 4 kV/cm.

18. Method according to claim 2, wherein the plant seeds (3) are exposed to a pulsed electrical field.

19. System (1) according to claim 13, wherein the conditioning system (2) has a temperature and/or pressure controller (19).

20. System (1) according to claim 13, wherein the capacitor (6) comprises at least two electrodes (9) which are connected to a pulse generator as a voltage source (11).

Description

[0038] In the drawings:

[0039] FIG. 1 shows a schematic representation of an exemplary embodiment of a system for disintegration of plant seeds according to the invention:

[0040] FIG. 2 shows photos of wheat grains after they have been squeezed in a texture analyzer: one control sample dry, one control sample after soaking, one sample after the treatment with an electrical field and soaking;

[0041] FIG. 3 shows an image for illustrating the characterization of the examining positions during an EDX analysis (energy-dispersive X-ray spectroscopy) for the determination of the distribution of oxygen in wheat grains;

[0042] FIG. 4 shows a chart for illustrating the thorough moistening of untreated control samples directly at the beginning of thorough moistening;

[0043] FIG. 5 shows a chart for illustrating the thorough moistening of grain samples conditioned by means of electrical fields directly at the beginning of thorough moistening;

[0044] FIG. 6 shows a chart for illustrating the thorough moistening of grain samples conditioned by means of electrical fields after 10 hours of thorough moistening;

[0045] FIG. 7 shows a chart for illustrating the thorough moistening of untreated grain samples after 24 hours of thorough moistening; and

[0046] FIG. 8 shows a diagram for illustrating the better disintegration of plant seeds treated according to the invention.

[0047] Below, an exemplary method for conditioning plant seeds and an exemplary embodiment of a system for disintegration of plant seeds according to the present invention are illustrated with reference to FIG. 1.

[0048] The system 1 shown in FIG. 1 comprises a conditioning system 2 for conditioning plant seeds 3, a disintegration device 4 for disintegration of the conditioned plant seeds, and a separating device 5 for separating different fractions of the disintegrated plant seeds. The plant seeds 3 are schematically shown as circles in FIG. 1.

[0049] The conditioning system 2 comprises a capacitor 6 for generating an electrical field.

[0050] In the shown embodiment, the conditioning system comprises a tempering cell 7 and a metering device 8 by means of which plant seeds 3 are introduced into the tempering cell 7 which is symbolized by arrows.

[0051] In the shown embodiment, the capacitor 6 comprises two electrodes 9 which are connected to a voltage source 11 via energy lines 10. Two capacitors 6 are shown by way of example. The electrodes 9 of the one capacitor are arranged in the tempering cell 7 and can generate an electrical field in the tempering cell 7. The other capacitor 6 is provided in the region of the metering device 8 and is embodied such that plant seeds 3 can be exposed to an electrical field while passing the metering device 8. Of course, it is not obligatory to provide two capacitors, it would equally be possible to only provide the capacitor in the tempering cell 7 or only in the region of the metering device 8. For a better overview, only one energy line 10 to one of the two electrodes 9 of one capacitor 10 is drawn in.

[0052] In the shown embodiment, the electrodes 9 of a capacitor 6 are arranged in parallel with respect to each other which makes it possible to generate a homogeneous electrical field for a uniform sample treatment. However, other variants of the electrode arrangement are also conceivable, for example, a coaxial or colinear arrangement.

[0053] As a voltage source 11, a pulse generator, for example a high-voltage pulse generator, such as a Marx generator, can be employed by which electric pulses of a high-voltage in a kilovolt range and a short duration in a micro- to millisecond range can be generated.

[0054] To condition the plant seeds 3, for example, at least 10 electric pulses, preferably 10 to 200, and particularly preferred 30 to 50 electric pulses can be introduced. When an electrical field of 0.3 kV/cm to 10 kV/cm is applied, an energy input of more than 1 kJ/kg into the planted seeds 3 is achieved, for example of 1 kJ/kg to 20 kJ/kg, preferably of 8 kJ/kg to 12 kJ/kg.

[0055] Thereby, a controlled cell disruption of the plant seeds 3 can be achieved by electroporating the plant seeds 3, for example, by means of the pulsed electrical field.

[0056] The voltage source 11 is connected via a control line 12 to a central control unit 13 which controls the voltage source.

[0057] In the shown embodiment of FIG. 1, the conditioning system 8 furthermore includes a wetting device 14 for moistening the plant seeds 3. The wetting device 14 for moistening the plant seeds 3 is embodied in the tempering cell 7 by way of example. It includes a storage container 15 which is connected with a spraying device 17 disposed in the tempering cell 7 via a supply line 16. In the storage container 15, a moistening liquid 18 can be contained which can be transported via the supply line 16 to the spraying device 17 and there be distributed inside the tempering cell 7. The moistening liquid 18 can be added to the plant seeds 3 in this manner. The addition of the moistening liquid 18 can also be controlled via the central control unit 13 which is connected to the wetting device 14 via a further control line 12.

[0058] In the shown embodiment, a temperature and/or pressure controller 19 is furthermore provided in the tempering cell 7. The controller 19 can include, for example, a thermostat 20 which is arranged in the tempering cell 7 and by means of which the temperature in the tempering cell 7 can be controlled to a predetermined value. Control can be accomplished via the central control unit 13 which is connected to the thermostat 20 via a further control line 12 in the exemplary embodiment. Although this is not explicitly shown in FIG. 1, a pressure controller can furthermore be provided in the tempering cell 7 to adjust a predetermined pressure inside the tempering cell 7. A pH controller for controlling the pH value of the mixture of plant seeds 3 and moistening liquid 18 is also conceivable.

[0059] The exemplary conditioning system 2 of FIG. 1 permits to carry out the method for conditioning plant seeds according to the invention by exposing the plant seeds 3 to an electrical field. In the process, the plant seeds can be electroporated by means of an electrical field, and a defined cell disruption can be performed. During conditioning, the elasticity of the plant seeds 3 can be improved and adjusted to a predetermined range. Thus, the plant seeds, for example cereal grains, that means cereals such as wheat, can be prepared for a subsequent disintegration process, for example a grinding process, which positively influences the grinding behavior. The treatment is facilitated by means of an electrical field and accelerates, for example, the wetting and thorough moistening of the plant seeds 3 with the moistening liquid 18 and permits a purposeful influence on the elasticity of the plant seeds. This improves the breaking behavior of the plant seeds and reduces flour loss, which will be demonstrated below with reference to test examples, by improving the separation of the flour fraction from the bran.

[0060] In one embodiment, enzymes can be added to the wetting liquid which accelerate the wetting or thorough moistening, respectively, or positively influence the texture or structure of the plant seed 3 for subsequent disintegration in any other way. For example, hemi-cellulolytic enzymes can be employed, for example hemi-cellulases, cellulases, glucanases, laccases, proteases, amylases, which further reduce the required tempering time in the tempering cell 7 and optimize the separation of the seed coat from the seed kernel, for example the bran from the endosperm in case of cereals, and thus optimize the grinding yield. Hemi-cellulases include pentosanases, for example arabinases and xylanases (such as endo-1-4-β-xylanase, endo-1-3-β-xylanase, exo-1-4-β-xylanase, exo-1-3-β-xylanase or arabino-furanosidase, ferulic acid esterase, hydroxycinnamic acid esterase, acetic acid esterase). Further possible hemi-cellusases are hesosanases, such as e. g. ß-glucanase, galactase, or mannase.

[0061] Apart from the addition of enzymes via the moistening liquid 18, enzymes can also act on components of the plant seeds 3 in other ways. For example, by means of the electrical fields, endogenous enzymes can be released, in particular during electroporation, which, after a correspondingly long tempering time or by adjusting a temperature or pressure or pH value optimal for the enzyme activity, can be subsequently activated via temperature and/or pressure control.

[0062] By means of all these measures, the structure and texture of the plant seeds 3 can be conditioned and adapted to the desired disintegration properties of the plant seed 3. For example, in this manner, the elasticity of the seed coat and/or the elasticity of the seed grain can be adjusted very well.

[0063] The conditioned plant seeds 3 are supplied from the tempering cell 7 to the disintegration device 4 via a transfer line 21 after conditioning. In the disintegration device 4, the conditioned plant seeds are disintegrated, for which, for example, pressure disintegration, stroke disintegration, grate disintegration, cutting disintegration and/or impact disintegration, or peeling, can be employed. Disintegration machines include, for example, crushers, mills, peeling machines, or other mechanical disintegrators, such as vapor peelers.

[0064] The disintegrated plant seeds 3 are transferred from the disintegration device 4 into the separating device 5 via a transfer point 22. In the separating device 5, different fractions of the disintegrated plant seeds are separated from each other. For example, the coat of peeled plant seeds, such as e. g. peeled chickpeas, rice and soya beans, can be separated. Possible methods for separating the fractions are, for example, screening or classifying. In cereal mills, classifiers are often employed by means of which solids can be classified according to defined criteria, such as particle size, density, inertia, and the floating or lamination behavior, and thus different fractions (that means fractions of different particle properties) can be separated from one another.

[0065] The fraction of the plant seeds desired by disintegration is finally guided out from the separating device via the outlet 23. The fraction which does not yet have the desired properties can be returned to the disintegration device 4 via a return line according to the exemplary embodiment, and be disintegrated again. Of course, instead of returning it, this fraction can also be transferred to a further, second disintegration device (not shown).

[0066] The product guidance of disintegration and separation is carried out in cereal mills by grinding in roll mills and subsequent classification. In the process, a run through a disintegration device 4 and a subsequent separating device 5 is referred to as passage. In the exemplary embodiment of FIG. 1, thus an exemplary disintegration passage 25 with a disintegration step carried out in a disintegration device 4 and a subsequent separation of different fractions in a separating device 5 is shown.

[0067] Below, by means of some concrete test results, exemplary embodiments of the method according to the invention and the advantages achieved thereby are represented.

[0068] For the treatment of the cereals with pulsed electrical fields (PEF), the grains were covered with water. A ratio of 100 g (cereals):800 g (water) was selected. However, any other ratio could have been selected in which it can be ensured that the cereal is completely wetted. The treatment with PEF was accomplished in a batch system with a treatment cell having a capacity of 900 ml. The applied field strength was 3 kV/cm, the energy input 10 kJ/kg. Subsequently, the grains were transferred to a screen and separated from the treatment water. Already directly after the PEF treatment (in which the grains were made with water only for 2 minutes and thus clearly shorter than the usual hour), a proportion of approximately 18 g of water remained on the grains as a surface wetting.

[0069] After the treatment, a determination of the texture properties was done by means of a texture analyzer with respect to the compression and cutting forces. After a PEF treatment and soaking, an increase of the maximal compression force of 34.94 kg for untreated samples to 42.96 kg was determined. The fracture behavior of the PEF-treated samples thus advantageously showed to be more elastic and less brittle than that of untreated control samples. The seed coat of PEF-treated grains thus falls apart into fewer parts, and therefore, the endosperm can be more easily separated than in the dry or the soaked sample, which, however, was not treated by PEF (see FIG. 2).

[0070] The analysis of the water distribution in the grain was carried out directly after treatment, after 10 and 30 minutes, and after 1, 2, 4, 10 and 24 hours. A control sample was analyzed in parallel with the same method. By means of an EDX analysis, the distribution of the elements in grains was determined, and the penetration of water was characterized by the increase in the proportion of oxygen. The examination positions are represented in FIG. 3.

[0071] The wheat grains treated by means of PEF had, as shown in FIGS. 4 to 7, a better water distribution already at the beginning of the thorough moistening than the untreated samples, which can be identified by the course of the line above the mean value (MW) plus standard deviation (S). Already after 10 hours, the PEF-treated grains had a uniform thorough moistening of the endosperm optimal for grinding, while this was only reached after 24 hours in untreated samples.

[0072] The loosening of the endosperm structure and the loosening of the connection between the aleurone layer and the flour kernel caused thereby permitted the shortening of the tempering time with a comparable flour yield.

[0073] Below, a possible embodiment of the invention is represented by way of example by means of a test example.

[0074] For the tests, wheat (Triticum aestivum L., winter bread wheat. Class Butaro. August 2017) of one batch was filled into the treatment container of a discontinuous PEF system in portions of 400 g. Subsequently, 300 ml of tap water (optionally with the enzyme xylanase dissolved therein, 10-100 ppm, based on cereal) were poured on it and the container was PEF-treated for 20 s. 31 pulses with 30 kV and 450 J each were emitted to the grains, the specific energy input was 20 kJ/kg per batch. After a contact time with the water of altogether 60 s, the water was centrifugated off. The humidity content of the grains was between 15.2 and 16.4% after centrifugation. Per adjustment, 8 tests were made to obtain a sufficient cereal amount for grinding in a laboratory mill (Bihler MLU).

[0075] The flour yield (extraction rate) was adjusted to an ash value of 0.63. The ash content is a decisive quality feature and correlates with the extraction rate. The extraction rate is determined from the ratio of the parts by weight of the flour to the total weight in percent. This is an index of the efficiency of the grinding process by comparing the weight of the overall output with the starting weight. In the tests, the parts by weight of the passage flours and the bran centrifugation flours were added and calculated in relation to the wheat weighed in.

[0076] Formula for the Extraction Rate:

[00001]$E=\frac{\mathrm{EP}+\mathrm{EK}}{\mathrm{EG}}*100$ [0077] E=extraction rate [%]; [0078] EP=extraction of passage flour [g]; [0079] EK=extraction of bran centrifugation flour [g]; [0080] EG=total initial weight [g]

[0081] Moreover, the extraction rate with an adapted ash content was employed as a parameter. It was calculated by a formula which fixes the ash percentage since this is a quality feature and has an influence on the extraction rate.

[0082] Formula for the Adapted Extraction Rate:

[00002]$\mathrm{EP}*\mathrm{AP}+\mathrm{AEK}*\mathrm{AK}=\mathrm{EG}*\mathrm{AG}$$\mathrm{EG}=\mathrm{EP}+\mathrm{AEK}$$\mathrm{AEK}=\frac{\mathrm{EP}*\left(\mathrm{AG}-\mathrm{AP}\right)}{\mathrm{AK}-\mathrm{AG}}$$\mathrm{AE}=\frac{\mathrm{AEK}+\mathrm{EP}}{\mathrm{EG}}$ [0083] EP=extraction of passage flour [g] [0084] AEK=adapted extraction of bran centrfugation flour [f] [0085] EG=total initial weight [g] [0086] AP=ash passage flour [% in dry matter] [0087] AK=ash bran centrifugation flour [% in dry matter] [0088] AG=ash desired percentage [0089] AE=adapted extraction value

[0090] FIG. 8 shows that the conditioning with an electrical field, both alone and in combination with the enzyme xylanase, surprisingly increases the flour yield. Compared to the untreated reference, the additional yield was improved by 1.4% by PEF, and by 1.8% by the combination of PEF and enzyme.

REFERENCE NUMERALS

[0091] 1 system [0092] 2 conditioning system [0093] 3 plant seeds [0094] 4 disintegration device [0095] 5 separating device [0096] 6 capacitor [0097] 7 tempering cell [0098] 8 metering device [0099] 9 electrodes [0100] 10 energy line [0101] 11 voltage source [0102] 12 control line [0103] 13 control unit [0104] 14 wetting device [0105] 15 storage container [0106] 16 supply line [0107] 17 spraying device [0108] 18 moistening liquid [0109] 19 temperature and/or pressure controller [0110] 20 thermostat [0111] 21 transfer line [0112] 22 transfer point [0113] 23 output [0114] 24 return line [0115] 25 passage