CH662477A5 - METHOD FOR TREATING NUTS. - Google Patents

Description

The invention relates to a method according to the preamble of claim 1.

With cocoa beans in particular, peeling is often carried out in connection with a heat treatment. For example, EP-OS 68 221 describes a special, combined moisture and heat treatment process with which a high yield and excellent peeling can be achieved. In general, another heat treatment, namely roasting, is also carried out after the peeling. Eventually the product will marry.

Another heat treatment is often used before grinding, namely drying. For example, AT-PS 218 840 describes that after drying, the regrind should be cooled again in order to bring it to about room temperature. Grinding at room temperature is also described in other references, e.g. in GB-PS 317 335, FR-PS 855 149 and DE-PSen 506 096 and

2,831,073. So you can see that experts at all times believed that milling at room temperature was the cheapest, presumably because the nuts have a certain brittleness at these temperatures. At such temperatures, the cocoa butter contained in the cocoa kernel is not yet liquid. For this reason, it is recommended everywhere to cool down after the previous heat treatment.

This prejudice is so imprinted that even in a document in which hot grinding is proposed, in FR-PS 1 159 306, in connection with the peeling, a previous heat treatment in a drying apparatus is proposed, at the end of which the cocoa beans in larger pieces are broken up in order to be able to remove the shells more easily, but a cooling zone is also provided at the outlet of the drying apparatus so that the bean pieces are fed to the grinding in a cold state after the shells have been broken and removed. For this reason, a roller mill with heatable rollers must be provided, which is mechanically and energetically complex. US Pat. No. 1,512,466 goes the same way when grinding various nuts, in particular those fruits which contain a high proportion of fat, such as almonds, coffee beans and cocoa beans. Even then, it was recognized that hot grinding is particularly beneficial for fatty fruits, but this path has never been followed consistently and thought through, rather leaving it later, as the more recently cited literature reference shows.

The effect is also known that the temperature of the nuts rises during grinding because part of the grinding energy used is absorbed as heat energy by the nuts (DE-OS 2 002 958). This heating has sometimes been promoted even by extensive work with heated grinding rollers (US Pat. No. 1,512,466).

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In a generic method, cocoa butter is heated before peeling and rough crushing, then roasted with the addition of heat and then goes from roasting to grinding. The roasting takes place in a gas stream with an inlet temperature of 204 ° C, which flows in cocurrent with the cocoa beans over a longer distance. Nothing is said about the temperatures of the gas flow and the cocoa beans at the end of the roasting treatment. However, it can be assumed that the cocoa beans are still noticeably warm when they are handed over for grinding.

The invention has for its object to make a particularly favorable compromise of the process management available between sterile operation, low energy consumption and good taste of the product produced.

To achieve this object, the method according to the invention is characterized in that the still warm fruits have a temperature of above 80 ° C when fed to the hot grinding.

Since the nuts remain at a relatively high temperature between the previous heat treatment and the grinding, the sterilization time is prolonged and germ growth is avoided as far as possible before the grinding. The energy consumption is favorable because, on the one hand, no energy-consuming cooling is required before grinding, and on the other hand, grinding at the inlet temperatures of the millbase according to the invention at which the vegetable fat contained, e.g. Cocoa butter, liquefied, requires less energy. After hot milling, a product of very good quality, in particular in the form of a pasty mass, is obtained,

to which the supply of nuts with the temperatures according to the invention contributes to grinding.

The process can be carried out in such a way that there is a time period of at most 8 minutes, better at most 5 minutes and even better at most 2 minutes between the heat treatment and the grinding.

A plant according to the invention for treating fatty nuts, in particular cocoa beans, and preferred developments of this plant are the subject of claims 10 to 13.

It is expedient to carry out any roasting of the nuts in process steps which are preferably present anyway, in particular in the heat treatment and / or hot grinding mentioned. A distribution of the roasting over several process steps is particularly gentle and even.

The preferably provided hot grinding under negative pressure is known per se (EP-OS 18 607). In this publication, a grinding temperature of 100 to 130 ° C is mentioned, but without warm supply of the ground material.

Further details result from the following description of a diagram shown in the drawing and illustrating several embodiment variants and the associated description.

According to the known peeling method according to EP-OS 68 221, commercially available cocoa beans are fed to a funnel 2 and thus to the inlet opening 3 of a network device 1 via a metering device 26. The network apparatus 1 has a screw conveyor 4, which transports the beans through a humidification zone and mixes them with moisture, to which zone moisture in the form of water vapor or hot water is fed via a humidification device 5. A heat treatment already takes place here, because the most preferred steam has a temperature of at least 120 ° C, e.g. B. 120 ° - 150 ° C. The residence time of the beans or the conveying speed of the

Screw 4 and the water or steam temperature are set as explained in the EP-OS mentioned, so that reference can be made to the same.

The cocoa beans pass through a lock 7 and reach a fluidized bed apparatus 8, within which a mechanical auxiliary conveyor 13 is preferably provided, in order to ensure that the residence times of the individual beans in the fluidized bed each become the same. The auxiliary conveyor 13 is advantageously implemented in the form of a chain conveyor, with a closed chain 15 which can be driven via rotatable rollers 16, 17 and which feeds the beans to an outlet opening 18. The cocoa beans are subjected to a further heat treatment in the fluidized bed apparatus 8, the hot air washing around the bean surface from all sides (fluidization). This heat treatment also kills all harmful germs completely.

At the exit of the fluidized bed apparatus 8, a lock 48 and a peeling machine 20 are provided, which can be formed by an impact peeler, but here is a rubber roller peeler, as is normally used for rice. After peeling by the two rubber rollers 50, 51, shells and cores fall over a chute 53 and enter an air classifier or aspiration channel 54. The guidance and heating of the air (or an inert gas), the recovery of the thermal energy by means of heat exchangers 32, 33 etc. is described in detail in the aforementioned EP-OS and therefore does not need to be explained in detail.

While the shells in the air classifier 54 are now pulled off upwards in the direction of arrow 6, the cores fall down and can get into one of two outlets 21 or 22 depending on the position of a flap 58. Of course, in the case of a specific system, if desired only one outlet 21 or 22 can be provided, in which case the switchover option by means of the flap 58 is eliminated.

The device described so far corresponds to the state of the art according to EP-OS 68 221, which has already been mentioned several times. While a shaft roaster was connected to the outlet opening 21 in the known device, a separate roasting process and thus the associated mechanical device can be omitted in the present method , so that the heat exchanger 33 is only operated with the exhaust gases from the known heating or gas combustion device 29, which is provided for heating the air (or inert gas) supplied to the fluidized bed apparatus 8 via a line 27.

The millbase emerging from the outlets 21 and 22 preferably has a temperature above 80 °, in particular above 90 °, its temperature generally around 110 °, i.e. will be between 100 and 120 °. This temperature is preferably achieved due to a heat treatment in the fluidized bed apparatus 8 for a period of 60 to 480 s with a temperature of at least 150 °, in practice between 150 ° and 220 °. The moisture content of the ground material is approximately between 3 and 5%, e.g. 4.3%. In this state, the ground material can already be fed to the inlet funnel 9 of a narrow gap mill 10, as is indicated by a broken line 11. However, the mill 9 can also be preceded by an intermediate treatment in a continuous mixing apparatus 12, for example formed by a vertical mixer, the outlet 22 being connected to the one filling funnel 14 of the mixing apparatus 12, whereas additives for improving the taste or aroma are connected via a further filling funnel 19 are fed. For example, the funnel 19 in the production of chocolate

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load glucose or water, whereas for the production of cocoa powder more or less concentrated potash solution can be poured into the funnel 19. The material mixed in this way in the mixing apparatus 12 then reaches the filling funnel 9 of the mill 10 via a line 23.

Another possibility is indicated at the outlet 21 of the air classifier 54, the ground material being subjected to a further heat treatment in a horizontal screw mixer 24. This will be particularly advantageous if, for some reason, the regrind does not have the desired moisture, for example due to liquid additives 19a, which can also be added to the screw mixer 24 and which correspond to the known additives discussed above with reference to the filling funnel 19. Hot air, for example of approximately 100 ° C., is fed to the horizontal screw mixer 24 via a line 25. Aroma-damaging substances can also be removed from the material in this way. If desired, a drying process is provided in a screw device 28, from which the air is extracted via a vacuum suction line 30. For this purpose, the screw apparatus 28 is closed at least at its exit, preferably also at its entrance, in a known manner by a lock 31.

Whatever the treatment chosen, depending on the starting material used and the desired end product, the regrind emerging from the outlet 21 reaches the mill 10 either directly, at the outlet of the horizontal screw mixer 24 or at the outlet of the screw apparatus 28 via a line 32a.

The mill 10 is preferably designed in the manner described in EP-PS 18 607 and in particular has a second grinding stage 10a combined with it in a single housing. Both grinding stages 10, 10a are expediently designed as impact or shear mills, the grinding process advantageously taking place in a low-oxygen atmosphere for the reasons described above. In principle, this can be done by passing an inert gas stream through it, but a vacuum or vacuum can also be formed in the manner described in EP-PS 18 607. This not only protects the material from harmful oxidation (e.g. fatty acids), especially with cocoa, but also removes harmful vapors, the so-called vapors, and thus helps to improve the aroma.

Depending on the desired end product and the type used, either a pulverulent mass or a liquid to pulpy cocoa mass will be found at the exit of the second stage 10a, the latter using a liquefier 33a d.i. essentially a heatable mixer, is kept in the liquid state, the temperature only having to be chosen so high that the fat escaping from the fruit during grinding, in particular cocoa butter, does not solidify.

As mentioned, this grinding process in the grinding stages 10, 10a gives a powdery or pulp-shaped product with grain sizes which are in any case less than 1 mm and generally have a spectrum between 0.015 and 0.8 mm. At the exit of the pad-del mixer 33a, such a grain size distribution can result that a sieve with a mesh size of 75 | i 8.5 G% (based on the dry matter) is retained, whereas the rest already passes through. The product has undergone further gentle roasting due to its temperature at the outlet 21 or the inlet funnel 9 and due to the heating during the grinding process, after the parameters in the fluidized bed apparatus 8 can be selected such that there is a slight roasting. At this point the water content has decreased by approximately 3%, i.e. it is in a range between just above 0% and about 2%, for example 1.3%.

A third grinding stage for fine grinding or final grinding on a three- or five-roll mill 34 or 35 can then be connected directly to the second grinding stage 10a. For this purpose, the heated and thus liquefied material is drawn off via a line 36 with the aid of a pump 37, it being able to be fed to either the three-roll mill 34 or the five-roll mill 35 by means of a three-way valve V. If desired, the valve V is omitted in a certain installation and only the three-roll mill 34 or the five-roll mill 35 is connected to the line 36 via the pump 37. At this point, the product temperature is only between 85 ° and 95 ° due to the cooling effect of the vacuum, so that roasting can be avoided.

In the rolling mills 34 and 35, for example, the millbase can be milled in such a way that the average grain size is 20 (X), the grain size distribution being such that there is only a residue of 0.2 G on a sieve with a mesh size of 75 (i % (based on the dry matter) At the same time, the regrind is brought to the required temperature, eg to a storage temperature between 55 ° and 65 °. If desired, however, the roasting can also be continued on rolling mills 34 and 35 by providing a heating device for at least one roller is provided, for example for the third and fourth rollers of the five-roll mill 35. Finally, if desired, this roasting process can be continued in a thin-film evaporator 38, as is indicated, for example, at the exit of the three-roll mill 34. Such a thin-film evaporator 38 can be used in known way to continue to improve aroma by degassing and e to contribute, if necessary, by adding flavor-enhancing additives. For example, a blower 39 can be provided for the passage of air in counterflow, and water can be injected in a finely divided manner in a known manner in order to use air or water vapors (the thin-film evaporator 38 is evacuated via a connection 40) to remove the harmful vapors ( Acids and smelly substances). Here again, glucose, but also granulated sugar and milk powder in dissolved or powder form (otherwise they have to be added to mixers 12 and 24) can be considered as additives.

Of course, it is also possible to do without one or the other process step, for example the thin-film evaporator 38. It should also be mentioned that the transport speed in the process steps before grinding in the mill 10 must be selected such that, in contrast to the known processes, there is no substantial cooling, i.e. the peeled fruit should reach the mill 10 in less than 10 minutes. In experiments, 8 minutes was chosen as the top limit, with a speed of less than 5 minutes at which a substantial cooling could be avoided. In practice, times between 30 s and 2 minutes have proven to be achievable and cheap. Although the method has been described with reference to the drawing using the example of the treatment of cocoa beans with which the advantages of the method in question can be most clearly achieved, it is understood that the method can also be applied to other nuts, such as almonds, soybeans, etc. . Also, the hot grinding could be done in less than three

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Steps, for example, take place in only one, whereas on the other hand it is also possible to provide more steps.

Instead of the first heat treatment in the screw network apparatus 1, a perforated conveyor belt can also be provided, which is guided through a steam climate zone (so-called “steam belt”). Alternatively, the fruit can be moved in a pressure container by means of a stirrer in a steam atmosphere, sterilization also taking place.

With regard to the heat exchanger 33, it goes without saying that it can also be operated with other exhaust gases and with exhaust air from the fluidized bed apparatus.

Practical attempts to grind cocoa

Vacuum (maximum 0.8 bar) have shown that the product has a noticeably better quality. It can be assumed that this effect is due to the warm introduction of the cocoa quarry into the grinding stage, with thin layers being formed. The heat favors the removal of moisture in a vacuum, and with the increased amount of moisture, more pollutants are removed. With the same treatment, there is therefore an improved taste compared to conventional processes or, if desired, the further treatment can be shortened. Above all, this can save the thin-film evaporator 12 in most applications.

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1 sheet of drawings

Claims (13)

662 477 1. A method for treating fatty nuts, in particular cocoa beans, in which the nuts are heat-treated for peeling or afterwards and then the still warm fruits are ground, characterized in that the still warm fruits are heated to a temperature of have above 80 ° C. 2. The method according to claim 1, characterized in that the hot grinding is carried out without a separate energy supply. 2nd PATENT CLAIMS 3. The method according to claim 1 or 2, characterized in that the fruits are fed immediately after peeling, optionally with an intermediate treatment of the fruits to improve taste or aroma and / or to dry the hot grinding, and that the fruits are expediently in the process steps be roasted at an elevated temperature, preferably via the heat treatment and hot grinding process steps, avoiding a separate roasting process step. 4. The method according to any one of claims 1 to 3, characterized in that the hot grinding is carried out in a low-oxygen atmosphere, preferably under reduced pressure or vacuum. 5. The method according to any one of claims 1 to 4, characterized in that the fruits are fed to the hot grinding at a temperature above 90 ° C, preferably between 100 ° C and 120 ° C, optionally at 110 ° C. 6. The method according to any one of claims 1 to 5, characterized in that the heat treatment preceding the hot grinding at a temperature of at least 150 ° C, for. B. between 150 ° C and 220 ° C, optionally for a period of 60 to 480 s. 7. The method according to any one of claims 1 to 6, characterized in that the hot grinding up to a grain size below 1 mm, preferably below 0.8 mm, is carried out, in particular the grain sizes are between 0.8 and 0.015 mm and, for example, a pulpy or powdery mass is obtained. 8. The method according to any one of claims 1 to 7, characterized in that the hot grinding within a period of at most 8 minutes, preferably within at most 5 minutes, in particular at most 2 minutes, e.g. in half a minute after the heat treatment is done. 9. The method according to any one of claims 1 to 8, characterized in that the hot grinding is carried out in at least two stages. 10. shell fruit treatment plant for performing the method according to one of claims 1 to 9, with a heating device for heating the unpeeled nuts, a downstream peeling machine and a grinding device for grinding the peeled fruit, characterized in that the plant with regard to the spatial arrangement of the plant parts and the Compliance with the throughput speed of the fruits and temperatures is designed such that the fruits reach the grinding device (10, 10a, 34, 35) at a temperature above 80 ° C. 11. Plant according to claim 10, characterized by a vacuum or vacuum mill (10,10a). 12. Plant according to claim 10 or 11, characterized in that the grinding device has a, preferably two-stage, narrow-gap mill (10, 10a), expediently designed as an impact or shear mill, in particular a Multi-roll mill (34; 35), e.g. a three-roll mill, is connected downstream. 13. Plant according to one of claims 10 to 12, characterized in that, following a multi-stage grinding device (10, 10a, 34 or 35), a thin-film evaporator (38) for post-treatment, preferably post-roasting, optionally a taste or Aroma treatment is provided.