WO2018015532A1

WO2018015532A1 - Gentle cocoabreaker

Info

Publication number: WO2018015532A1
Application number: PCT/EP2017/068468
Authority: WO
Inventors: Tobias Lohmüller
Original assignee: Bühler Barth Gmbh
Priority date: 2016-07-22
Filing date: 2017-07-21
Publication date: 2018-01-25
Also published as: EP3487312A1

Abstract

A method and a device for treating shellfruits or oilseeds is provided, wherein a force is imparted on a shellfruit. The force is selected such that the kernel of the shellfruit is separated from the shell without substantially breaking the shell.

Description

Gentle Cocoabreaker

The present invention relates to the treatment of shellfruits or oilseeds, such as beans, nuts and, in particular, cocoa beans, specifically for separating the kernel from the shell of the fruit. When peeling unroasted shellfruits or oilseeds, such as nuts or beans, and in particular cocoa beans, the fruits are conventionally subjected to a pre-treatment involving moisture and heat. This pre-treatment leads to the separation of the kernel from the shell in the unpeeled shellfruit. For example, EP 0 068 221 A2 discusses the problems involved with the separation of the shell from the kernel of roasted or untreated shellfruits, in particular the problem that in the untreated shellfruits the fruit or kernel is still attached to the shell that causes difficulty in separation fruit from shell. Furthermore, the breaking of the whole shellfruit, in particular cocoa beans, in a one-step procedure causes the formation of fine pieces having dimensions of less than about 1mm, that contain shell fragments and kernel fragments (50/50%) that cannot be separated within the following process. Furthermore, the fine partials cause substantial losses during the cocoa liquor and chocolate production.

EP 0 068 221 A2 therefore suggests a method for removing the shell of a shellfruit which starts from a predetermined moisture content of the shellfruit followed by a heat treatment, thereby facilitating the removal of the shells and further increasing the efficiency and the quality of the product.

It is an object of the present invention to provide a method and system for separating the shell from the kernel of a shellfruit avoiding the need for any pre-treatment and to reduce yield losses due to reduced fine partical generation

This object is achieved with the method and device according to the independent claims. The dependent claims define embodiments of the present invention.

It is the gist of the present invention to provide for the separation or isolation of the kernel from the shell of an untreated shellfruit by imparting a force to the shellfruit that achieves a separation of the kernel from the shell without breaking the shell. After this separation, the shell is broken, for example by known means such as a baffle plate, and the resultant fragments can be separated. This separation can be performed using known measures such as an air separator.

The invention can be used for treating various kinds of fruits or seeds that comprise a shell, for instance a hard, dry shell or testa, that should be separated from a kernel. Therefore, the term "shellfruit" in the context of the present specification and claims is intended to encompass any such fruit and seed, such as oilseeds, nuts, beans, and in particular cocoa beans.

With the present invention, any pre-treatment of the shellfruit, in particular a pre-treatment using heat or steam, can be omitted. Consequently, the force is preferably imparted at room temperature.

Any method suitable for imparting tangential, vertical and/or horizontal forces to the shellfruit can be used, as long as the force is sufficient to substantially separate or isolate the kernel from the shell but still leaves the shell of the shellfruit intact. In addition to isolating the kernel from the shell, the kernel usually is broken into pieces along pre-existing breaking points inside the still intact shell.

A preferred way of imparting the necessary force is to impart a shearing force to the shellfruit. This can be achieved, for example, by providing a pair of rollers and passing the shellfruit through a gap between the rollers which preferably counter-rotate. By suitably choosing the width of the gap and the rotating speeds, which preferably differ for the two rollers, the imparted shearing force can be controlled.

Another possibility for imparting the necessary force to the shellfruit is passing the shellfruit between vibrating plates. In this case, the two plates are preferably arranged horizontally having a gap therebetween allowing the shellfruit to pass through the gap. The force can be controlled by suitably selecting the amplitude and frequency of the vibrations.

With the present invention, efficient separation of the shell from the kernel of an untreated shellfruit can be achieved, thereby improving the efficiency of the separation compared to conventional methods, since breaking an untreated shellfruit increases the losses due to fragments that include shell parts strongly adhered to kernel fragments. Furthermore, by avoiding heat and/or moisture pre-treatment, the energy consumption of the treatment method can be reduced.

The invention is described in more detail with reference to the Figures, wherein

Figure 1 shows (a) an untreated cocoa bean, (b) a cocoa bean subsequent to being treated using the method of the present invention and (c) the cocoa bean of (b) with the kernel being broken inside the shell, and

Figure 2 shows a device according to an embodiment of the present invention.

Figure la shows a schematic drawing of the cross-section of an untreated cocoa bean or seed. A shell or testa 1 surrounds the kernel 2. In an untreated cocoa bean, the kernel is firmly adhered to the shell. A conventional pre-treatment leads to an abrupt expansion of the shell and thus to a separation of the shell from the kernel.

With the present invention, such separation can equally be achieved without the need of heat or moisture by imparting a force to the cocoa bean 10 that is sufficient to separate the shell 1 1 from the kernel 12 but does not break the shell 1 1. A cocoa bean 10 after being treated with the method of the invention is shown in Figure 1 b, wherein the shell 1 1 is isolated from the kernel 12.

While conventional (cold) breaking of a cocoa bean, for example in a centrifugal crusher or roll crusher, leads to a high particle distribution which necessitates a complex separating step and to a high ratio of fine elements that are usually lost in the subsequent process, the method of the present invention, due to the lower imparted force, results in larger kernel fragments that are still confined by the intact shell 1 1. In particular, the kernel is usually broken at preexisting breaking points or surfaces.

Thereby, a more uniform particle distribution is achieved which reduces the complexity and demands regarding the subsequent separation of the kernel and shell fragments achieved after breaking the shell subsequent to the treatment of the present invention. For example, after breaking the shell 12 of a cocoa bean 10 as shown in Figure lc, simple aspiration while breaking the shell may be sufficient for efficiently separating the shell and kernel fragments. This further leads to a reduced footprint of the machine, i.e. the space needed and the energy consumption of the machine is reduced.

A device according to an exemplary embodiment of the present invention is shown in Figure 2. The shellfruits to be treated pass the gap between rollers 1 and 2. When treating cocoa beans, fermented cocoa beans are treated that have not been subjected to a heat or moisture pre-treatment. While roller 1 rotates anticlockwise, roller 2 rotates clockwise at a rotating speed different from the rotating speed of roller 1. By suitably choosing the rotating speeds, the speed difference, the size of the rollers and the width of the gap, the shearing force that acts on the shellfruit can be controlled.

The roller speed correlates with the surface of the rollers and controls the required

throughput. The gap width should be adapted to the bean count, such as choosing a gap size of 6-8mm for bean count 120. For smaller or higher bean counts the gap needs to be adjusted. The bean count describes the size of the shellfruits, and is given by the number of shellfruits, e.g. cocoa beans, per 100g. That is, the gap width should be smaller for larger bean counts, for example a bean count 140, whereas for a bean count 80, the gap width should be greater.

Furthermore, when adjusting the gap width and roller speeds, the level of fermentation must be taken into account since the level of fermentation has an influence on the thickness of the shell of the shellfruits. Specifically, for a lower fermentation level, i.e. a lower quality or incomplete fermentation, greater shearing forces must be imparted on the shellfruits, compared with shellfruits that were exposed to a better fermentation. Thereby, the weight proportion of the shellfruit shells varies between about 10% to 28%. Therefore, the rotation speeds of the rollers must be adapted to the specifications of the raw material.

Moreover, the moisture content of the shellfruits must be taken into account. The standard moisture content is about 5% to 9%. In case the shellfruits to be treated have previously been subjected to humidification with water or steam, which may occur, for example, when debacterizing or sterilizing the shellfruits, this should be considered when selecting the shearing force that acts on the shellfruit, by suitably selecting the relevant parameters, in particular rotating speeds and gap width. However, as previously described, a pre-treatment of the raw material with water or steam for facilitating the removal of the shell is not necessary according to the present invention.

According to the present invention, all the above parameters of the device are chosen to achieve the desired separation of the kernel of the shellfruit from the shell without breaking the shell. As a result, the shellfruits that have passed the machine preferably have a broken kernel, broken along the pre-existing breaking points of the kernel. These kernel fragments are, however, held together by the still intact shell. The treated shellfruits leave the machine at outlet 5 and can then enter further steps of the treatment. For example, the shell can subsequently be broken using a baffle plate resulting in a mixture of shell and kernel fragments. Due to the pre-treatment with the method of the invention, only a small amount of the kernel fragments are still connected to shell fragments, for example since the separation of the kernel from the shell was not complete in the previous treatment step. Therefore, isolating the resulting kernel fragments from the shell fragments and fragments that include both, can be achieved more efficiently by known techniques, such as aspiration using an air separator.

That is, with the method of the present invention, the kernel cannot only be separated from the shell but already be broken at existing breaking points or lines by the use of tangential, vertical and/or horizontal forces, thereby minimizing or avoiding the formation of fine particles. The subsequent step of breaking the shell results in a relatively homogenous particle size distribution which allows the subsequent separation from the kernel fragments from the remaining parts more efficiently.

The following table summarizes the particle size distribution resulting from the above- described method. The given amounts indicate the weight percent resulting from the mesh sizes used in a sieve that are indicated in the first column. The table shows that substantially all bean fragments have sizes greater than about 7 mm.

Claims

1. A method of treating shellfruits comprising the step of imparting a force on a shellfruit wherein the force is selected such that the kernel of the shellfruit is separated from the shell without substantially breaking the shell.

2. The method of claim 1 , wherein no pre-treatment of the shellfruit, in particular a pre- treatment using heat or steam, is performed prior to the step of imparting the shearing force.

3. The method of claim 1 or 2, wherein the step of imparting the force is performed at room temperature.

4. The method of any one of the preceding claims, wherein the step of imparting a force comprises imparting a shearing force on the shellfruit.

5. The method of any one of the preceding claims, wherein the step of imparting a force comprises passing the shellfruit through a gap between counterrotating rollers, particularly rotating at different rotational speeds.

6. The method of claim 5, wherein the force is selected by controlling the gap width, the rotational speeds, in particular the speed difference, and/or the diameters of the rollers.

7. The method of any of claims 1 to 4 wherein the step of imparting a force comprises passing the shellfruit between vibrating plates.

8. The method of any one of the preceding claims, further comprising a step of breaking the shell after the step of imparting the force, thereby obtaining shell fragments.

9. The method of claim 7, further comprising a step of separating the shell fragments from the treated shellfruits.

10. The method of any one of the preceding claims, wherein the shellfruit is a seed or a nut, and in particular a cocoa bean.

1 1. A device for treating shellfruits, comprising means for imparting a force on a shellfruit, wherein the means for imparting the force is configured to produce a force that is adapted to separate the kernel of the shellfruit/oilseed from the shell without substantially breaking the shell.

12. The device of claim 1 1 , wherein the means for imparting a force is configured to impart a shearing force on the shellfruit.

13. The device of claim 1 1 or 12, wherein the means for imparting a force comprises two counterrotating rollers, particularly rotating at different rotating speeds, wherein the device is adapted to control the force by adjusting the width of a gap between the rollers and/or the rotational speeds and/or the speed difference of the rollers.

14. The device of claim 1 1 , wherein the means for imparting a force comprises a pair of vibrating plates separated by a gap, the width of the gap being configured such that the shellfruit can pass between the plates.

15. The device of any of claims 1 1 to 14, further comprising a baffle plate for breaking the shell of the shellfruit, thereby obtaining shell fragments downstream the means for imparting a shearing force, and an air separator for separating the shell fragments from the treated shellfruits.