Method And Device For Treating Nuts, In Particular For Producing Nuts With Improved Shelling Properties

Abstract

The invention relates to a method for treating shell-fruits (3), in particular for producing shell-fruits (3) with improved shelling properties in comparison to untreated shell-fruits (3). The invention further relates to a device (1) for treating shell-fruits (3), in particular for producing shell-fruits (3) with improved shelling properties in comparison to untreated shell-fruits (3), comprising a hermetically sealable treatment chamber (2) for conditioning the shell-fruits (3). In order to provide a method and a device for treating shell-fruits which do not damage the contents of the kernel and simultaneously permit improved shelling of the shell-fruits and the opened shell to be better separated from the kernel, the method according to the invention comprises softening the shell of the shell-fruits (3) by applying an electric field, and the device according to the invention comprises at least one capacitor (4) for generating an electric field in the treatment chamber (2).

Claims

1. Method for treating shell-fruits (3), in particular, for producing shell-fruits (3) with improved shelling properties in comparison with untreated shell-fruits (3), comprising the following treatment step for said shell-fruits (3): a) softening a shell of said shell-fruits (3) by applying an electric field.

2. Method according to claim 1, where when applying the electric field, an energy input of at least 1 kJ/kg, preferably from 3 to 8 kJ/kg is applied to said shell-fruits.

3. Method according to claim 1 or 2, where an electric field of 0.5 kV/cm to 2 kV/cm is applied.

4. Method according to claim 1, where the shell is softened by way of electrical pulses.

5. Method according to claim 4, where said shell is softened with at least 10 electrical pulses, preferably 10 to 200 electrical pulses, more preferably 30 to 50 electrical pulses.

6. Method according to claim 1, comprising the further treatment step of: b) conditioning said shell-fruits.

7. Method according to claim 6, where said shell-fruits (3) are conditioned by applying an overpressure and/or an increase in temperature and/or by the action of a conditioning agent (11).

8. Method according to claim 6, one of the claims 6 to 7, where step a) of applying the electric field is carried out simultaneously with or prior to step b) of conditioning.

9. Method according to claim 7, where the temperature is increased in step b) to above 100 C., preferably to 100 C. to 120 C., and/or an overpressure of at least 1 bar, preferably an overpressure of 1 bar to 3 bar is applied.

10. Method according to claim 6, where the treatment time in step b) is less than 40 minutes, preferably less than 30 minutes and more preferably less than 20 minutes.

11. Method according to claim 6, where steam treatment is performed in step b).

12. Method according to claim 1, comprising at least one of the following steps subsequent to treatment steps a) and optionally b): c) shelling said treated shell-fruits (3); d) drying said shell-fruits (3), preferably said shelled shell-fruits (3); e) removing a skin of said shell-fruits (3); f) separating the fruit kernels from the remainder of said shell-fruit (3); g) crushing said shell-fruit (3); and h) extracting a constituent, preferably from the remainder of said shell-fruit (3), where the constituent is preferably an oil.

13. Method according to claim 1, where said shell-fruit (3) is selected from the group consisting of: beechnut, nut, chestnut, sweet chestnut, acorn, almond, pistachio, pine nuts, kernels, apricot kernels, grated coconut, where said shell-fruit (3) is preferably a nut selected from the group consisting of: hazelnut, walnut, peanut, hemp nut, macadamia nut, sycamore nut, tagua nut, water caltrop, cashew nut, Brazil nut, pecan nut, shea nut, marl nut, coconut, nutmeg fruit.

14. Device (1) for treating shell-fruits (3), in particular, for producing shell-fruits (3) with improved shelling properties in comparison to untreated shell-fruits (3), comprising a hermetically sealable treatment chamber (2) for conditioning said shell-fruits (3), and at least one capacitor (4) for generating an electric field in said treatment chamber (2).

15. Device according to claim 14, where said capacitor comprises at least two electrodes (5) connected to a pulse generator (8).

16. Method according to claim 2, where an electric field of 0.5 kV/cm to 2 kV/cm is applied.

17. Method according to claim 7, where step a) of applying the electric field is carried out simultaneously with or prior to step b) of conditioning.

18. Method according to claim 8, where the temperature is increased in step b) to above 100 C., preferably to 100 C. to 120 C., and/or an overpressure of at least 1 bar, preferably an overpressure of 1 bar to 3 bar is applied.

19. Method according to claim 7, where the treatment time in step b) is less than 40 minutes, preferably less than 30 minutes and more preferably less than 20 minutes.

20. Method according to claim 8, where the treatment time in step b) is less than 40 minutes, preferably less than 30 minutes and more preferably less than 20 minutes.

Description

[0033] In the following, the invention shall be described by way of example in detail with reference to the drawings and subsequent experimental examples using advantageous embodiments. The advantageous further developments and configurations illustrated there are each independent of each other and can be combined with one another at random, depending on the requirement of the application, where:

[0034] FIG. 1 shows an exemplary method for treating shell-fruits according to an exemplary embodiment;

[0035] FIG. 2 shows an exemplary embodiment of a device according to the invention for treating shell-fruits;

[0036] FIG. 3 shows cashew nuts exposed to an electric field as well as to steam treatment;

[0037] FIG. 4 shows images of shelled cashew nuts of FIG. 3;

[0038] FIG. 5 shows an enlarged view of a cashew nut which has been treated only with steam and not with an electric field;

[0039] FIG. 6 shows a bar graph showing the moisture content of cashew nuts treated with steam or subjected to steam treatment and an electric field after shelling;

[0040] FIG. 7 shows a bar graph of the liquid content of the samples of FIG. 6 after an additional drying step; and

[0041] FIG. 8 shows images of shelled cashew nut samples which have been subjected only to steam treatment or to steam treatment and additionally an electric field.

[0042] Hereafter, an exemplary method for treating shell-fruits according to the present invention shall be presented with reference to the flow diagram in FIG. 1.

[0043] The method according to the invention for treating shell-fruits, comprising softening a fruit body of the shell-fruits by applying an electric field, is embedded in a method for producing shell-fruits with improved shelling properties in comparison to untreated nuts.

[0044] The flow diagram of FIG. 1 therefore overall represents, by way of example, a method for shelling shell-fruits, such as cashew nuts.

[0045] In methods customary in the trade for shelling shell-fruits, such as cashew nuts, the shell-fruits are sorted in one step, for example, in a perforated cylinder, to obtain groups of evenly sized cashew nuts.

[0046] In conventional methods for shelling cashew nuts, the cashew nuts after sorting are filled directly into a treatment chamber in which the cashew nuts are then conditioned. The conditioning can be effected, for example, by steam treatment at temperatures of 110 C. to 116 C. and overpressure of 1.0 bar to 2.5 bar with a treatment time of 20 to 30 minutes.

[0047] After steam treatment, the nuts to be shelled are cooled down, for example, for 10 to 12 hours at room temperature and then shelled using a shelling machine.

[0048] The method according to the invention for treating shell-fruits, in particular, for producing shell-fruits with improved shelling properties in comparison to untreated shell-fruits, comprises the step of softening a fruit body of the shell-fruits by applying an electric field.

[0049] In the flow diagram of the exemplary method of FIG. 1, the softening step by applying an electric field takes place between the step of sorting and filling into the treatment chamber.

[0050] As shall be explained below, however, the step of applying an electric field to soften a fruit body can also be performed simultaneously with the conditioning in the treatment chamber.

[0051] A device for such an application where an electric field is simultaneously applied and the shell-fruits are conditioned in a treatment chamber is shown in an exemplary embodiment in FIG. 2.

[0052] Device 1 shown in FIG. 2 comprises a hermetically sealable treatment chamber 2 into which shell-fruits 3, illustrated by way of example as circles, can be filled and conditioned. Device 1 of FIG. 2 further comprises a capacitor 4 for generating an electric field in treatment chamber 2. Capacitor 4 in the illustrated embodiment comprises two electrodes 5 which are connected via power lines 6 to a voltage source 7. In the embodiment shown, the two electrodes 5 of capacitor 6 are arranged on oppositely disposed sides and parallel to each other. A homogeneous electric field for uniform sample treatment can be generated with such an electrode arrangement. However, other variants of the electrode arrangement are also conceivable, for example, a coaxial or collinear arrangement.

[0053] A pulse generator, for example, a high-voltage pulse generator, such as a Marx generator, can be used as a voltage source with which electrical pulses of a high voltage in the kilovolt range and of short duration in the micro to millisecond range can be generated.

[0054] To soften a fruit body, at least 10 electrical pulses, preferably 10 to 200 and, particularly preferably, 30 to 50 electrical pulses can be introduced. When an electric field of 0.5 to 2 kV/cm is applied, an energy input into the shell-fruits of more than 1 kJ, for example, 5 to 20 kJ/kg, is obtained.

[0055] The voltage source is connected via a control line 9 to a central control unit 10 which controls the voltage source.

[0056] In treatment chamber 2, shell-fruits 3 can be conditioned in various ways.

[0057] A first conditioning option is to allow a conditioning substance or agent 11 to act on shell-fruits 3. In the embodiment shown by way of example, conditioning agent 11 is stored in a storage container 12 and can be introduced by way of a pump 13 from storage container 12 via a supply line 14 through a dosing inlet 15 that opens into treatment chamber 2.

[0058] In the embodiment shown, the opening of inlet 15 is arranged by way of example in a side wall of treatment chamber 2. It is equally possible to provide the inlet opening in the region of the base or the ceiling of the treatment chamber, or to provide several inlet openings at different locations of treatment chamber 2.

[0059] Storage container 12, in particular a level indicator (not shown) of the storage container, which outputs a signal when conditioning agent is to be topped up, or pump 13, respectively, is connected via control lines 16 and 17 to central control unit 10. In this way, control unit 10 can regulate pump 13 and thereby the supply of conditioning agent into the treatment chamber or output a warning signal when conditioning agent 11 is to be topped up in storage container 12.

[0060] A further conditioning option is to heat shell-fruits 3. Device 1 of FIG. 2 shown by way of example comprises a heating element 18 for this purpose. Heating element 18 is connected via a further control line 19 to control unit 10, so that control unit 10 can actuate heating element 8 and a desired temperature can then be adjusted in treatment chamber using heating element 8. A closed loop can be accomplished in that device 1 further comprises a temperature measuring device 20 which is also connected to control unit 10 via a further control line 21.

[0061] Another type of conditioning can be achieved according to exemplary device 1 by applying overpressure. The embodiment of device 1 shown by way of example comprises a pressure gauge 22 which measures the pressure in the treatment chamber and can output it via a further control line 23 to control unit 10. Furthermore, device 1 of the exemplary embodiment comprises a pressure valve 24 which is connected via a further control line 25 to control unit 10. Control unit 10 can output a control signal via control line 25 to pressure valve 24 and open or close the latter in order to adjust the pressure in treatment chamber 2. An overpressure can be obtained in the treatment chamber, for example, by introducing compressed air or by way of a compressor which compresses a fluid disposed in treatment chamber 2 (not shown).

[0062] The embodiment shown by way of example generates the overpressure in that a conditioning agent 11, for example water, introduced into treatment chamber 2 is heated using heating element 18. Since treatment chamber 2 can be closed hermitically or in fluid-tight manner, an overpressure can be established in treatment chamber 2 when heating conditioning agent 11. Steam at a temperature of 110 C. to 120 C. and an overpressure of 1 to 2.5 bar can be generated in the treatment chamber in this way.

[0063] Instead of a pressure gauge 22 and a pressure valve 24, both of which are connected via control line 23, 25 to a control unit 10, only a pressure relief valve (not shown) could be provided which opens when a predetermined overpressure is exceeded and thus maintains the pressure in treatment chamber 2 at a predetermined value in a simple manner.

[0064] For homogeneous distribution of shell-fruits 3 to be treated, device 1 shown by way of example comprises a mixer 26, for example, a stirring unit. Mixer 26 can again be connected via a control line 27 to and be controlled by central control unit 10.

[0065] Exemplary embodiments of the method according to the invention shall be described below on the basis of some concrete experimental results.

EXPERIMENT 1

[0066] Treating shell-fruits by way of steam conditioning and applying an electric field to produce shell-fruits with improved shelling properties.

[0067] In this series of experiments, cashew nuts were used as exemplary shell-fruits.

[0068] Three sample groups and one control group were prepared:

[0069] The cashew nuts of all samples were subjected to steam treatment. For this purpose, 10 nuts were filled into a steam boiler with 750 ml of water. Steam treatment at temperatures of 110 to 116 C., a pressure of 1.5 bar was performed in the steam boiler for a treatment time of 20 minutes. Prior to conditioning by steam treatment, the cashew nuts were pretreated as follows: [0070] a. untreated cashew nuts (control sample); [0071] b. Cashew nuts into which an energy input of 5 kJ/kg was introduced; [0072] c. Cashew nuts into which an energy input of 10 kJ/kg was introduced; [0073] d. Cashew nuts into which an energy input of 20 kJ/kg was introduced.

[0074] For the energy input, the cashew nuts were exposed to electrical pulses of an electric field of 1.07 kV/cm. Depending on the sample, the cashew nuts were treated with 45 pulses (sample b corresponding to 5 kJ/kg), 90 pulses (sample c corresponding to 10 kJ/kg) and 181 pulses (sample d corresponding to 20 kJ/kg).

[0075] FIG. 3 shows the external appearance of the cashew nuts after their steam treatment.

[0076] As can be seen in FIG. 3, the more energy is introduced by way of electrical pulses, the darker the cashew nuts become. The cashew nuts darkening is an indication that the fruit bodies soften and nut oils and nut acids leak out of the cells during the steam treatment.

[0077] After the conditioned nuts were cooled down overnight at room temperature for about 18 hours, they were shelled by use of a knife.

[0078] Illustrations of the shelled samples are shown in FIG. 4. It can be clearly seen in FIG. 4 that the nuts, in which the fruit bodies were softened by applying an electric field, could be easily extracted as a whole, without fractures, from the shell. The untreated sample on the other hand, which was only exposed to steam conditioning and no electric field, broke several times during shelling and the attempt to extract the fruit body from the shell.

[0079] It can also be seen in FIG. 4 that the shells of the samples which were additionally treated with electric fields have more moisture. This indicates the release of constituents, such as oils, from the nuts. In contrast to the cashew nuts which were pretreated by ways of electric fields, the cashew nut of the untreated samples often broke when extracted from the shell (see FIG. 5), which is due, inter alia, to the fact that the epidermis of the nut stuck to the shell in the untreated samples.

[0080] This series of experiments has therefore shown that it is possible to produce shell-fruits with improved shelling properties using the method according to the invention or to improve the extraction of constituents from the shell-fruits.

EXPERIMENT 2

[0081] Improving the shelling properties and determining the moisture content of shell-fruits using cashew nuts as an example.

[0082] In this series of experiments, the moisture content and the shelling properties of cashew nuts were investigated in which the fruit bodies were softened by applying an electric field and which were then conditioned by steam treatment.

[0083] For this purpose, the following control groups and samples were prepared: [0084] a. a first control group that was not exposed to any electric field and was subjected to steam treatment for 30 minutes; [0085] b. a second control group that was not exposed to an electric field and was subjected to steam treatment for 20 minutes; [0086] c. a sample of cashew nuts into which an energy input of 5 kJ/kg of electrical energy was introduced and which were subsequently subjected to steam treatment for 20 minutes.

[0087] The energy input of 5 kJ/kg was effected by the action of 45 pulses of an electric field of 1.07 KV/cm. The pulse width was 5-50 s, depending on the filling quantity, the conductivity and the electrode capacity.

[0088] The nuts of the sample and control groups, respectively, were subsequently subjected to steam treatment, as was done with experimental series 1.

[0089] After steam treatment, the cashew nuts were cooled down in an open vessel for about twelve hours at room temperature, and the moisture content of the nuts was then determined in a moisture balance with halogen heating.

[0090] The moisture contents of the samples used are shown in FIG. 6. FIG. 6 shows that the moisture content of all samples is below a moisture content of 10%, which is common for cashew nuts that are subjected to steam treatment.

[0091] After cooling, the nuts were shelled.

[0092] Illustrations of the nuts of control group a) and of sample group c) are shown in FIGS. 8a and 8b, respectively. FIG. 8 shows that the nuts of the control group, in which the fruit bodies were not softened by the application of an electric field, frequently broke out of the shells during shelling and extraction. By contrast, in the case of the nuts treated according to the method of the invention, the fruit bodies could be separated from the shell in a simple and complete manner.

[0093] The nuts were then dried at 72 C. for seven to eight hours to remove the shell skin from the fruit bodies.

[0094] The moisture contents of dried samples a) to c) are shown in FIG. 7. The moisture content was in all cases below 3%, which is the common moisture content for dried cashew nuts.

[0095] Finally, the dried cashew nuts of samples a) to c) of experimental series 2 were subjected to a sensory examination.

[0096] In a visual inspection, it is first be noted that the shell-fruits of group a), which have been steam treated for 30 minutes, are darker than the shell-fruits of groups b) and c), which have been steam treated for a shorter time.

[0097] The sensory taste examination delivered the following results: [0098] control group a): crisp, hard, roasted taste, taste reminiscent of peanut flavor, no cashew flavor [0099] control group b): crisp, hard, no roasting flavors, no cashew flavor [0100] control group c): softer than the control groups (however hard structure comparable to cashew nuts in the market), cashew flavor

[0101] The above experimental examples demonstrate by way of example that shell-fruits can be treated using the method according to the invention, for example, to improve their shelling properties or to better remove constituents from the shell-fruits.

REFERENCE NUMERALS

[0102] 1 device [0103] 2 treatment chamber [0104] 3 shell-fruits [0105] 4 capacitor [0106] 5 electrodes [0107] 6 power lines [0108] 7 voltage source [0109] 8 pulse generator [0110] 9 control line [0111] 10 control unit [0112] 11 conditioning agent [0113] 12 storage container [0114] 13 pump [0115] 14 supply line [0116] 15 insertion opening [0117] 16 control line [0118] 17 control line [0119] 18 heating element [0120] 19 control line [0121] 20 temperature measuring unit [0122] 21 control line [0123] 22 pressure gauge [0124] 23 control line [0125] 24 pressure valve [0126] 25 control line [0127] 26 mixer/stirring unit [0128] 27 control line