EP0838529B1 - Process for conditioning finely milled substances by humidifying the milling space - Google Patents

Abstract

Conversion of a coarse-grained or crystalline bulk solid into a fine conditioned powder, especially powdered sugar, comprises milling or grounding the grains and conditioning. The conditioning takes place simultaneously with the milling or grinding process. In the case of sugar the conditioning takes place in conditions of absolute air humidity of ≥ 17 (preferably ≥ 20) g/kg dry air. Milling or grinding is undertaken at ≥ 25 (preferably 40-45) degrees C.

Description

The invention relates to an improved method for the preparation of conditioned powder from coarse-grained or crystalline substances, in particular for the preparation of conditioned powdered sugar.

Powdered sugar is a by crushing crystalline Sugar-made product, the Grain size is generally less than 0.1 mm. The large surface of the ground sugar is affected in connection with the good water solubility of the Sucrose the shelf life of powdered sugar strong. So shows in a dry atmosphere ground Icing sugar through the grinding process and that connecting melting of the sugar on the fracture surface and the rapid cooling in the airflow glassy Structures on its surface. In the Inclusion of adsorption isotherms shows that this powdered sugar to adsorb high amounts of water can. By absorbing the water a recrystallization process on the surface of the Powdered sugar grains initiated. The recorded Water is quickly released again. If this Process of water absorption respectively -Delivery occurs in the icing sugar bag, the icing sugar moist and glued to the surface. The powdered sugar becomes hard (Roth, dissertation 1976, University of Karlsruhe, "Amorphization during shredding and recrystallization as causes of Agglomeration in powdered sugar ").

It is known through the powdered sugar mill downstream installation of conditioning systems, that is, from systems that have shelf life the powdered sugar by setting certain Temperature and humidity has been increased achieved that the process of water absorption and -Delivery in the area of the conditioning system has been moved and storable powdered sugar is produced could be.

It proves disadvantageous that following the Powdered sugar mill conditioning equipment installed need to be costly and space consuming are. In addition, the one following the grinding Conditioning time consuming.

The basis of the present invention So the technical problem is a process for the preparation of conditioned powder from coarse-grained or crystalline substances, in particular from granulated sugar, which is available in as short a time as possible and without major construction Effort to generate well storable, that is conditioned powder allows.

The technical problem underlying the invention is solved by a manufacturing process of conditioned powder, especially conditioned powder Powdered sugar is provided, whereby the coarse-grained or fine-crystalline used Substances, especially the one used Sugar, ground and conditioned and being the conditioning of the substances during grinding he follows. The invention therefore provides that the Conditioning, that is, the treatment of Fabrics in such a way that during the Storage no longer become hard, not in a separate, conditioning step following the grinding process is performed, but at the same time with the grinding. The invention accordingly the advantage that conditioned substances, especially conditioned sugar, already after the grinding, so that a time-consuming Post-treatment is no longer necessary. In addition, it is not necessary separate conditioning systems after the powder mill to be provided as the conditioning takes place in the grinding room itself.

The invention relates in a particularly preferred manner Way of making conditioned powdered sugar from sugar, for example galactose or preferably sucrose, for example as Refined sugar (EG quality I) or granulated sugar (EG quality II) can be present. Of course However, the invention can also be used for substances of others Composition, but the same or similar physical Properties to be used. such, a coarse-grained or crystalline structure containing substances can also be pectins. According to the invention can also mix different substances Composition in a single step ground together and conditioned become.

In a preferred embodiment, the invention relates to the aforementioned method, which is used at elevated Water content, especially with increased water content the air, particularly preferred with an absolute Air humidity (in g water per kg drier Air) of at least 17 g / kg, preferably of 17 g / kg to 30 g / kg and particularly preferably 25 to 26 g / kg. The one during grinding Conditioning is therefore preferred Execution solely by the fact that the humidity in the grinding chamber is increased. The Use of grinding aids such as organic Solvents, is not necessary, but will excluded according to the invention in a preferred embodiment.

The invention also relates to an aforementioned method, taking the conditioning at temperatures from at least 25 ° C, preferably from 25 ° C to 70 ° C, particularly preferably at 40 ° C to 48 ° C, in particular 45 ° C, is carried out.

However, the invention is expressly not limited to the minimum values for air humidity and temperature mentioned. Critical to the invention success is particularly the simultaneity of grinding and conditioning, wherein the discontinuing the conditioning parameters in a simple and known manner can be determined by the conditioning means of determination of a _W -value (water activity), the lump number or invert sugar moiety is assessed and the parameters are adjusted accordingly.

According to the invention, the temperature is preferred and the humidity during conditioning and grinding constantly, for example by means of electronic control devices.

Finally, the invention also relates to the aforementioned Procedure, following the simultaneously grinding and conditioning an intermediate storage is connected, the Duration essentially depends on the process engineering Parameters of the environment is determined.

The conditioning provided according to the invention downstream optional intermediate storage can be done by a simple stirred tank as a buffer container between Mill and packaging system is installed, the one defined interim storage time of the powdered sugar guaranteed. This buffer container enables one constant movement of the powdered sugar.

Further advantageous embodiments of the invention can be found in the subclaims.

The invention is based on the exemplary embodiments and the associated figures explained.

Figur 1

eine schematische Darstellung einer Anlage zur Durchführung des erfindungsgemäßen Verfahrens,

Figur 2

eine grafische Darstellung des zeitlichen Verlaufs des a_W-Wertes von bei unterschiedlichen Luftfeuchtigkeiten vermahlenen Puderzuckerproben,

Figur 3

eine grafische Darstellung des zeitlichen Verlaufes des a_W-Wertes in Abhängigkeit von der Dauer einer nachgeschalteten Zwischenlagerung und

Figur 4

eine grafische Darstellung des zeitlichen Verlaufes des a_W-Wertes in Abhängigkeit von der Dauer einer nachgeschalteten Zwischenlagerung ohne Zufuhr von Konditio nierungszuluft.

Show it:

Figure 1

2 shows a schematic representation of a plant for carrying out the method according to the invention,

Figure 2

a graphical representation of the time course of the a _W value of powdered sugar samples ground at different atmospheric humidity,

Figure 3

a graphic representation of the time course of the a _W value depending on the duration of a subsequent intermediate storage and

Figure 4

a graphical representation of the time course of the a _W value depending on the duration of a subsequent intermediate storage without the supply of conditioning air.

Example 1: Preparation of conditioned icing sugar from sucrose.

Figure 1 shows schematically the structure of an invention grinding room system 100 to be used This includes a grinding room 1, a discharge shaft 2, a rotary valve 3 and a screw conveyor 5. The grinding chamber 1 has a mill 7 with a sugar feed shaft 9 and a suction opening 8 on. The grinding chamber 1 also has a filter 11 and a fan 13. Finally there is a humidification system 19 in the grinding chamber 1, the two arranged parallel to each other Has nozzles 21. These will fall below a setpoint value of the humidity of one electronic controller 15 activated, which is a target-actual digital display to display the absolute humidity in the grinding room 1. Figure 1 also represents a heater 23.

The function of the system 100 is as follows represents.

By means of the heating device 23, a temperature of 40 ° C. with a fluctuation range of ± 1 ° C. is constantly set in the grinding chamber 1. The humidification system 19 is designed so that a water loading of the grinding chamber air of 18 g water per kg dry air is possible. The nozzles 21, which generate water particles with a diameter of 5 μm during spraying, serve this purpose. As soon as the desired climate has been set in the grinding chamber 1, crystalline sugar Z is introduced into the mill 7 via the feed shaft 9 and ground. The grinding process therefore takes place in a tempered and humidified grinding chamber 1 (volume of the grinding chamber 1: 193 m ² ). The air intake of the mill 7 through the intake opening 8 is 2,300 m ³ / h. The purge air quantity SL is used to clean the filter 11. The throughput of the fan 13, which is connected downstream of the filter 11, is 2,520 m ³ / h. The fan 13 removes both the purge air SL and the intake air AL of the mill 7. The intake air AL for the mill 7 comes directly from the grinding chamber 1, while the purge air SL is dry control air which enters the grinding chamber 1 from the outside.

The system 100 shown in FIG. 1 was used about different settings of the moisture loading the grinding chamber air of 12 to 26 g / kg dry Examine air, taking the grinding chamber temperature was at 40 ° C. The through the heater 23 achieved temperature must be by means of a in this Integrated control device constant being held.

FIG. 2 shows the course over time of the a _W value of powdered sugar samples (sucrose), measured at 40 ° C., the samples being ground at different moisture loads in the grinding chamber air.

The a _W value (water activity) defines the relative humidity that must prevail in the atmosphere surrounding a sample in order to avoid any water exchange between the sample and the air. It is given in units of 0 to 1 and therefore indicates the relative humidity that arises in a closed room above a substance sample at a defined temperature.

In cases where powdered sugar is not conditioned, it is observed that from a certain point in time after the sample has been taken from the grinding chamber, the moisture stored in the powdered sugar is rapidly desorbed. The time course of the a _W value shows an S-shaped characteristic. If the powdered sugar is conditioned, this S-shaped curve does not appear. It is recognized that there is a direct correlation between the behavior of the a _W value over a certain period after sampling and the storage behavior of the powdered sugar.

FIG. 2 shows samples of the freshly ground powdered sugar, each with different settings the grinding chamber humidification were generated. One finds an S-shaped course of the curves the powdered sugar samples at 12 to 15 g / kg Moisture loading were generated and a steady Course in the samples at 17 to 26 g / kg Humidity loading were generated. Freshly ground Powdered sugar with a moisture load on it Grinding chamber air of over 17 g / kg dry air is generated has therefore been conditioned. A subsequent subsequent to the grinding Conditioning is therefore unnecessary.

Finally, it can also be stated that the invention powdered sugar even after a long time Time is of excellent quality. This can be demonstrated quantitatively, for example be by using a mesh size of 0.300 mm is sieved and no residue remains.

Conditioned sugar also shows after years Storage under defined conditions no lump formation on.

Example 2: Conditioning icing sugar with subsequent interim storage

In order to achieve a standardized product quality, it can be advantageous to provide a container for the intermediate storage of the ground powdered sugar. For this purpose, the system 100 according to FIG. 1 can be modified in such a way that between the mill 7 and the packaging system (not shown), for example following the screw 5, a stirred tank, which is designed as a circulation tank, is used, which serves as a buffer or intermediate tank , FIG. 3 shows the course over time of the a _W value of ground powdered sugar during such an intermediate storage depending on the duration of the intermediate storage (measured at 40 ° C.). The moisture loading of the grinding chamber air was 25 to 26 g / kg dry air (at 40 ° C temperature in the grinding chamber), while the moisture loading of the conditioning air exchanged during the intermediate storage in the head space of the stirred tank (circulation) was 11 to 12 g / kg drier Air was fraud. The powdered sugar samples are to be classified as conditioned from the beginning to the end of the intermediate storage according to the time course of the a _W values.

FIG. 4 shows the time course of the a _W value of powdered sugar during the conditioning as a function of the duration of the intermediate storage (measured at 40 ° C.). The moisture content in the grinding chamber air was 17 g / kg dry air (40 ° C. ), while the intermediate storage took place without the supply of tempered or humidified air. In the buffer tank used for the intermediate storage, there is therefore only circulation, but no conditioning by adding tempered or humidified air. The powdered sugar samples are to be classified as conditioned from the beginning to the end of the intermediate storage according to the time course of the a _W values.

Claims (7)

1. Method for producing conditioned powder from coarse-grained or crystalline substances, wherein the substances are milled and conditioned, characterised in that the conditioning of the substances takes place during the milling process.
2. Method according to claim 1, characterised in that the coarse-grained or crystalline substances are sugars.
3. Method according to one of the preceding claims, characterised in that the sugar is saccharose.
4. Method according to one of the preceding claims, characterised in that the conditioning of the substances takes place with an elevated water content.
5. Method according to one of the preceding claims, characterised in that the conditioning of the substances takes place by milling them under conditions of an absolute air humidity of at least 17 g water/kg dry air, preferably at least 20 g water/kg dry air.
6. Method according to one of the preceding claims, characterised in that the conditioning of the substances takes place by milling them at a temperature of at least 25°C, preferably at 40°C to 45°C.
7. Method according to one of the preceding claims, characterised in that interim storage follows the conditioning which takes place during the milling process.

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