Abstract:
A mixing and kneading arrangement has a kneading vat and at least one kneading tool. A spray device in the arrangement has at least one spray nozzle in order to produce a spray mist in the kneading vat. Furthermore, the spray device has a feeding device for feeding liquid or liquefied dough components into the spray nozzle. The spray device furthermore has a source for gas which contains oxygen and a pressure unit, which sets the gas which contains oxygen under pressure. In a spray head in the spray nozzle, the liquid or liquefied dough components are combined with the gas which contains oxygen and which is under pressure to produce the spray mist.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention relates to a mixing and kneading arrangement with a kneading vat, at least one kneading tool, and a spray device comprising at least one spray nozzle for the production of spray mist in the kneading vat and comprising a feeding device for feeding liquid or liquefied dough components into the spray nozzle.  
       BACKGROUND OF THE INVENTION  
       [0002]     An arrangement of this nature is already known from DE 200 05 553 U1. With regard to the formation and the development of dough, the arrangement described therein still requires improvement.  
       SUMMARY OF THE INVENTION  
       [0003]     The object of the present invention is therefore to further develop a mixing and kneading arrangement of the type mentioned in the introduction in such a manner that the formation and the development of the dough in the mixing and kneading arrangement is improved.  
         [0004]     This object is attained according to the invention by means of a mixing and kneading arrangement having a spray device comprising a source for a gas which contains oxygen and a pressure unit which sets the gas containing oxygen under pressure, wherein the spray nozzle comprises a spray head, in which the liquid or liquefied dough components are combined with the gas which contains oxygen and which is under pressure in order to produce the spray mist.  
         [0005]     According to the invention, it has first been recognised that for the form ation and development of the dough in the mixing and kneading arrangement, it is of key importance to provide a controlled oxidation ratio during the mixing and kneading procedure. In the known mixing and kneading arrangements, this is essentially left to chance. The spray facility according to the invention makes it possible to produce a spray mist with a controllable oxygen content. Here, the oxygen content can be adjusted by selecting the gas which contains oxygen or the pressure with which the gas is fed to the spray head. A mixing and kneading arrangement results in which sufficient moisture is created in the dough components contained in the kneading vat. The oxidative process during the feeding of the liquid or liquefied dough components, which can be well controlled via the oxygen content, ensures improved dough formation. The mechanised energy which is applied via at least one kneading tool results in an improvement in the development of the dough.  
         [0006]     A spray device comprising several gas sources with assigned pressure units and at least one mixing unit for mixing the gases in a controlled manner increases flexibility when presetting a spray mist which is adapted to the individual mixing and kneading conditions. With the help of gas sources, gases with different oxygen quantities and, if necessary, with different quantities of other reactive components, can be provided.  
         [0007]     A spray device comprising at least one dosing unit for the dosed addition of at least one of the group of the liquid and liquefied dough components and at least one gas also makes it possible to control the composition of the spray mist by dosing individual components which are fed into the spray nozzle.  
         [0008]     A spray device comprising a dosing unit assigned to each gas source is further improved with regard to the setting options. The oxygen content can also be preset by dosing the individual gases which are fed in.  
         [0009]     A gas which contains oxygen, the gas being at least one of the group of the following gases: oxygen, air, nitrogen/oxygen mixture, has been shown to be particularly advantageous in tests in terms of achieving good baking results.  
         [0010]     A tempering unit for presetting the temperature of at least one of the group of the liquid and liquefied dough components and at least one gas before leaving the spray head creates a further setting option for the spray mist which is produced. Via the specified temperature of the components which are fed in via the spray nozzles, the temperature of the dough can also be influenced, which also enables an improvement to be made to the mixing and kneading result.  
         [0011]     An oxygen measuring sensor for presetting the oxygen content of at least one gas containing oxygen before leaving the spray head optimises the opportunities for setting the oxygen content of the spray mist.  
         [0012]     The invention will now be described in greater detail below by way of an exemplary embodiment which is explained with reference to the drawing.  
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0013]      FIG. 1  shows a diagram of a partial cross-section through a mixing and kneading arrangement with a spray facility, and  
         [0014]      FIG. 2  shows a top view of the mixing and kneading arrangement, wherein the components of the spray facility have been left out, with the exception of a spray mist which is produced from spray openings. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]     A mixing and kneading arrangement for dough, labelled overall as  1  in  FIG. 1 , has a kneading vat  2 , in which a kneading and guide rod  3  and a kneading spiral  4  are arranged as kneading tools. The kneading tools  3 ,  4  are connected with a head piece  5  of a control and drive unit  6  of the mixing and kneading arrangement  1 . The control and drive unit  6  can be used to move the head piece  5  upwards until the kneading tools  3  and  4  which are connected with the head piece  5  have moved out of the kneading vat  2 .  
         [0016]     The temperature of the dough or dough components  7  can be measured by a temperature sensor  8  of type PT100, which is arranged in a bare section of the kneading and guide rod  3 . Using a tempering facility which is not shown in greater detail and using the measured values of the temperature sensor  8 , and regulated on the basis of this data by a central computing unit in the control and drive unit  6 , the temperature of the dough  7  in the kneading vat  2  can be automatically adapted to a prespecified value.  
         [0017]     The kneading vat  2  is pivoted around its vertical symmetry axis. In order to rotate the kneading vat  2  during the kneading procedure, the mixing and kneading arrangement  1  comprises a drive motor  9 .  
         [0018]     In order to produce a spray mist in the kneading vat  2 , a plurality of spray nozzles  10  are used, of which a spray nozzle  10  with a spray head represented by a broken line is shown in  FIG. 1 . The position of the spray openings  11  on the vat side of the total of three spray nozzles  10  in the embodiment shown is shown in  FIG. 2 . In the area of the spray openings  11 , the spray nozzles  10  are mounted onto a cover  12  of the kneading vat  2 . The cover  12 , which does not rotate when the kneading vat  2  is rotated, seals the upper part of the kneading vat  2 , so that neither dough  7  nor dough components can escape. The spray openings  11  therefore all lie above the volume which is restricted by the kneading vat  2 . One of the spray openings  11  lies approximately on the rotating axis of the kneading vat  2 . The two other spray openings  11  lie mirror inverted in  FIG. 2  above and below the central spray opening  11  which lies on the rotating axis. This distance between these two additional spray openings  11  to a casing wall  13  of the kneading vat  2  is approximately the same as the distance between these two spray openings  11  and the central spray opening  11 .  
         [0019]     One of the total of three spray devices  14  which belong in each case to the spray nozzles  10 , is described below with reference to the spray device  14  shown in  FIG. 1 . The spray opening  11  represents the end of a mixing line  15  which runs in the spray nozzle  10 . On the end section of the spray nozzle  10  which lies opposite the spray opening  11 , an intersection  16  is arranged, in which a component feeding line  17  is connected with a gas mixing line  18 .  
         [0020]     The component feeding line  17  is used to feed in liquid or liquefied dough components to the spray nozzle  10 . Upstream of the intersection  16  in the component feeding line  17 , a tempering unit  19  is arranged in order to prespecify the temperature of the liquid or liquefied dough components. Upstream of the tempering unit  19 , a reservoir  20  for the liquid or liquefied dough components is arranged. The liquid or liquefied dough components can be water, salt, yeast and, if necessary, oxidation components, for example.  
         [0021]     Upstream of the intersection  16 , in the gas mixing line  18 , a tempering unit  21  is arranged in order to prespecify the temperature of the gas conveyed in the gas mixing line  18  before leaving the spray nozzle  10 . Upstream of the tempering unit  21 , in the gas mixing line  18 , a mixing unit  22  is arranged. Here, a first gas feeding line  23  and a second gas feeding line  24  join to form the gas mixing line  18 .  
         [0022]     Upstream of the mixing unit  22 , in the first gas feeding line  23 , a first dosing unit  25  is arranged. Upstream of the first dosing unit  25 , a first gas source  26  with an assigned first pressure unit  27  is arranged. Upstream of the mixing unit  22 , in the second gas feeding line  24 , a second dosing unit  28  is arranged. Upstream of the second dosing unit  28 , a second gas source  29  with an assigned second pressure unit  30  is arranged.  
         [0023]     The gases supplied from the gas sources  26 ,  29  contain oxygen. These gases can be pure oxygen, air, or a mixture of nitrogen and oxygen.  
         [0024]     The component feeding line  17  forms together with the tempering unit  19  and the reservoir  20  an feeding device  31  for feeding the liquid or liquefied dough components into the spray nozzle  10 . For the different spray nozzles  10 , it is not necessary in each case to provide separate gas sources  26 ,  29  or a separate feeding device  31 . Rather, it is possible that, depending on the arrangement of the flexibility when adjusting the spray mist in the individual spray nozzles  10 , a branching occurs in the feeding lines  17 ,  23 ,  24  or the mixing line  18  which runs through to the intersections  16  of the different spray nozzles  10 . Both the spray devices  14  and the feeding device  31  are connected via signals with the central computing unit of the control and drive unit  6 , so that control or regulation of the individual components in the devices  14 ,  31  is possible.  
         [0025]     The mixing and kneading arrangement  1  functions as follows: alongside the liquid or liquefied dough components, flour and, if necessary, additional non-liquid and non-liquefied components, are added to the kneading vat  2 , in order to produce the dough  7 . The addition of non-liquid and non-liquefied components is made using a feeding pipe  32  above the kneading spiral  4 . The addition of the liquid or liquefied dough components is made here via the spray nozzles  10 . In these nozzles, a mixture of the gases which contain oxygen which come from the gas sources  26 ,  29 , which is under pressure, is fed into the liquid or liquefied dough components. The spray mist which is produced as a result in the kneading vat  2  can therefore be well controlled with regard to its oxygen content. This control of the oxygen content is achieved via the mixing ratio of the gases from the gas sources  26 ,  29 , which can be set via the dosing units  25 ,  28  and the mixing unit  22 . The mixing ratio can in addition be achieved via the individual tempering of the gases from the gas sources  26 ,  29  via further tempering units arranged in the feeding lines  23 ,  24  and which are not shown. Due to the resulting controllable feeding of oxygen via the spray mist, sufficient moisturisation, in particular of the singular particles in the non-liquid dough components, in particular of the flour, is achieved. During the kneading process, an adequately aerobic situation is thus created in the dough  7 . Due to the fact that its oxidative process can be influenced as a result of the controllable oxygen content, the formation of the dough  7  is improved. For example, the redox pair oxygen and L-ascorbic acid, the most important flour treatment agent, can be made to react directly in the mixing and kneading arrangement  1 , thus improving and accelerating the dough development. These oxidative processes improve or accelerate the dough development in the kneading vat  2  within the kneading zone in which the kneading tools  3 ,  4  influence the dough, and within the remaining resting area of the kneading vat  2 . Here, the proteins contained in the dough in particular oxidise, which promotes the required agglutination of the dough.  
         [0026]     The arrangement of the spray nozzles  10  in the cover  12  guarantees an evenly distributed moisturisation of the dough or the dough components  7 . Due to the pressure units  27 ,  30  and via the corresponding adjustment options in the spray nozzles  10 , the form and degree of spraying via the spray mist can be variably adjusted. The temperature of the spray mist can also be adjusted via the tempering units  19 ,  21 . Via the tempering units  19 ,  21 , a fine adjustment of the oxygen content of the spray mist is also possible. With a variant of the mixing and kneading arrangement  1 , the oxygen content can be regulated on the basis of the measured values from an oxygen measuring sensor which is not shown, which can be arranged, for example, in the gas mixing line  18  adjacent to the tempering unit  21 . The oxygen sensor is connected via signals with the central computing unit of the control and drive unit  6 , so that an automatic adaptation of the oxygen content of the spray medium to a prespecified value is possible. The adaptation options described for the mixing and kneading arrangement  1  guarantee the production of different doughs  7 . Here in particular, an adaptation to the individual dough composition can be achieved. The dough which is thus produced and processed using the mixing and kneading arrangement  1  can then be further processed to create smaller dough pieces. In particular, prefermented and frozen smaller dough pieces can be produced from the dough produced using the mixing and kneading arrangement  1  without a reduction in quality.  
         [0027]     In addition, any formation of flour dust which may occur during the mixing phase is suppressed by the spray mist.  
         [0028]     Overall, the quality of the dough  7  produced and processed using the mixing and kneading arrangement  1  is controlled depending on the oxygen content, the rotational speed of the kneading spiral  4  and the temperature of the dough  7  which is regulated using the temperature sensor  8 .