The new approach to chocolate processing!

Friday, 01 May 2009

The following article offers a comparison between the conventional chocolate processing method and the alternative process offered by Duyvis Wiener Traditionally chocolate manufacturers have produced their chocolate recipes using kneaders, roller refiners and conches. Changes in this concept were simply inconceivable because the manufacturers were afraid of experiencing losses in quality and taste. Traditionally chocolate manufacturers have produced their chocolate recipes using kneaders, roller refiners and conches. Changes in this concept were simply inconceivable because the manufacturers were afraid of experiencing losses in quality and taste. The well known processing concept guarantees a fine range of quality chocolates, so why should you consider changing? The answer to this is that the economic situation has changed and so reducing production costs is vital to make the business profitable. Cost reducing changes in the production process, without making concessions to the product quality and taste, are now very welcome! Duyvis Wiener has a very long history in the development of compound and chocolate processing lines. Their W-85 choc line with ball mills and Taste Changer can offer a real alternative for the industry! When using such a system, the initial costs, as well as the operational costs, are reduced to a minimum without effect to quality and taste of the product. Chocolate processing – Advantages of a completely automated ball mill system compared to the conventional conching systems Conventional chocolate processing... In a conventional system for chocolate production the following devices are needed: • A kneader for the production of dough • A three or five roll refiner (or combination of these) for the production of rolled dough • A conche for the end production of chocolate. The capacity of this line is determined by the workable contents of the conche. This content, in combination with the chosen conching time, gives the resulting capacity. The kneader – For the manufacture of chocolate it is, of course, necessary to have a recipe. When manufacturing chocolate with a conventional system, we need, besides the specific recipe, also a ‘partial’ recipe for the production of the rolled dough. For the composition of the ‘partial’ recipe know-how and experiences are necessary and these are only possible by practical working experience. The composing of a ‘partial’ recipe is critical. The consistency of the rolled dough has to be just perfect to ensure a resulting correct fineness after leaving the roll. If the rolled dough, for instance, is too ‘wet’, it will stick to rolls and create under-fine, because the spreading of the rolled dough is not granted, caused by sticking to the rolls. A number of particles will stick together and slip through the rolls. If the dough is too ‘dry’, however, it will not easily be handed over on the rolls and the capacity will decrease because the rolls can hardly take the dough along. The kneader arms are driven by a powerful motor which is capable of making a good dough out of the different ingredients. Also, the temperature adjustment of the double walled trough is important. If the temperature is too low, the cocoa butter will crystallize during the kneading of the dough. Then, although the composition of the “partial” recipe is correct, the right consistency of the dough will not be achieved. If the temperature is too high, however, a certain aberration of the taste will occur by processes which will be started fully or partially (Milliard-reaction, caramellisation). A key issue for the kneader is the filling sequence of the ingredients. Too little or too much of each ingredient, or the wrong sequence, will destroy the partial recipe. Since this process is dependant on the skills of the operator, this is a very sensitive phase in the process. In the Wiener W-85 choc line the filling sequence is fully automatic which guarantees a consistent high quality product, completely independent of operating skills. Another advantage is that the filling and mixing uses very little energy. The roller refiner – The most important adjustment of the roll is the adjustment of the spalt-distances. These are important for the reduction of the particles. Also, these distances grant the correct transportation of the dough from one roll to the other. The temperature of the rolls has an influence on the reduction and the transport of the dough from one roll to another. The rolls, however, are not heated but cooled. The temperature of the rolls grants that the dough – at the end of its way through the roll – will merge into roll powder. This powder must be ‘dry’ when it leaves the roll and the cocoa butter part will have to be totally crystallized. This also gives the possibility, if the conditions are chosen correctly, to store the powder for a certain time. Some critical points which need to be taken into account, although the roll gives a tough and strong impression, it really is quite vulnerable. These vulnerable points could attach an undesirable effect to the end product. This result will only show after the product is ready and it could lead to rejection. These vulnerable points include damaged rolls which result in an undesirable fluctuation of the particle size. Also damage of the blade, which removes the crystallized dough from the last roll, could result in agglomerates in the powder. These agglomerates could consist during conching and thus get into the end product. The cost of repair of damaged rolls in order to bring them back into acceptable condition, are very high. The know-how and experience for adjusting the spalt-distance of the rolls will have to be prominently present, because the roll passage is once-only, determining the end fineness of the product, and the further routing of the product is irreversible. For correct functioning of the roll sufficient power is needed, whereas the turning of the rolls alone will require major power. But also for correct cooling of the rolls sufficient cooling water must be available. In the Wiener systems the refining is done by a ball mill which makes it far easier to monitor the process to get a consistent product. The conche –  There is a choice concerning the type of conche. This choice is made by the customer. The basic principle of the conche system, however, does not differ.  The basic principle is to surround all particles as much as possible with a fine film of butter (fat) and to separate eventual small agglomerates. Also, by adjusting the temperature of the conche, the processing of the product in the conche will decrease the eventually present humidity, incorporated by the ingredients, to a minimum. The fat acids with short chains – which are present in the cocoa liquor, giving it an unpleasant sour taste – will also disappear under the influence of temperature and surface increase in the air. The processing in the conche is as follows...The conche has a temperature of 45°C and is turning. A certain amount of powder is added. After a certain time, under influence of the temperature and the turning of the conche the cocoa liquor out of the powder will become fluid. By means of the power which is exerted by the conche onto the product, the product will change from powder to dry mass to a viscous liquid mass. When this consistency is reached, another amount of powder is added. This pre-treatment is repeated until all the powder of the recipe has been added to the conche. When the final recipe is ready, the processing intensity of the conche will be increased. In general this will mean that the speed will be accelerated. This acceleration will increase the product surface in contact with the air. This offers the opportunity that the fat acids with short chains and the humidity incorporated by the ingredients can be discharged more easily. The power which is put onto the viscous liquid by the speed acceleration will result in a plastification of the product and a composition of the different aromas of the individual ingredients. The choice of processing time in the conche is made by the customer, but based on experience in order to achieve the right product. This time is normally between 8 and 48 hours. When the processing time is achieved, this is also to be seen from the gloss of the product in the conche. Also, it is to be seen that the viscous liquid state of the product has decreased. Now the temperature of the conche is brought back to 45°C and the speed of the conche to ‘filling’ speed. After the product temperature has decreased to 45°C the amount of cocoa butter held back from the basic recipe and added to the conche, is being checked. When all the butter is added to the product, the emulsifier lecithin is mixed in. Also after this step we wait until all of the emulsifier is absorbed by the product. Last but not least, the eventual aromas are added, shortly before the discharge of the conche, in order to fully preserve the aromas which are often based on volatile elements. It may be clear that a powerful drive is needed to let the conche deal with a viscous liquid and a lot of energy is used for heating up and cooling down of the product. In the Wiener concept this energy and time consuming process is replaced by the Taste Changer. In the Taste Changer the same result is reached using a fraction of the money, energy and time! The Taste Changer is a combination of a shear stress device and a very efficient film evaporator. Hot, dry air and chocolate are intensively mixed, causing the moisture, volatile amino acids and off-flavours to be extracted from the mixture. The shear stress device temporarily reduces the viscosity of the mixture, thereby increasing the efficiency of the film vaporizer. The first developed alternative for conventional chocolate processing – the refiner conche After developing the conventional system people started looking for a system that was less labour intensive. Eventually, the refiner-conche derived from this. This machine consists of a horizontal cylinder of which the inner wall is covered with ribbed stroke plates. A shaft executed with paddles with scraper blades, runs through the centre of this cylinder. Grinding is achieved by letting the blades run against the ribbed wall with certain force. The refiner-conche is an all in one machine which means that all ingredients – except the lecithin and the aroma’s – are added at once in the beginning of the process. First the cocoa butter and the liquor are added, followed by the dry ingredients. When all above mentioned ingredients are mixed by the paddles, pressure will be set onto the blades and the refining (grinding) starts. However, due to the fact that the amount of product is high and a relatively low amount of the product will get in touch with the grinding system, there is very little control over the grinding process. As a result an unrepresentative particle size distribution is achieved. Besides this, the processing time in the refiner-conche is relatively long in order to achieve at least a reasonable grinding of the product. By inserting a ball mill together with a taste-changer to the system, the total output of the refiner-conche is significantly enlarged. The Wiener ball mill and the Taste-changer are set in series with the refiner-conche. With the refiner-conche the pre-grinding as a stand-alone machine is achieved. As soon as the product is able to be pumped, circulation over the ball mill and taste changer will start. The ball mill will achieve quick grinding of the particles. The complete content of the conche will be pumped through the ball mill assuring that the product will be ground properly. Because of the ball mill, the particle size distribution will be much smaller and the production time will be shortened significantly. Circulating over through the taste-changer replaces the conching part of the conventional process. The real alternative for conventional chocolate processing, the Wiener ball mill system After development of the refiner conche the developments went further and this resulted in a fully automated ball mill system called the Wiener W-85-Choc line. This system consists of: • ingredient storage and dosing system • computer controlled weighing unit • grinding unit consisting of in-line ball mills • Taste-Changer • storage tank Since the line is fully automated, operation is simple and human factors do not influence the consistency of the product. In fact the only important issue of this line is to keep the ingredient bunkers and tanks filled. The relevant recipes are saved in the control computer and the operator can choose the required recipe. All parameters for the process, as per recipe, are stored in the computer and can be up-dated and adjusted if necessary. After choosing the pre-set recipe, the process sequence starts. All ingredients are automatically dosed one by one in the weighing and mixing vessel and when the mixture is ready it will be discharged to the buffer vessel. The weighing and mixing is a batch process, however starting from the buffer vessel, which will never be empty unless the process is stopped, the downstream processing is continuous. From the buffer vessel the product is pumped through the ball mills where the required fineness is achieved. Leaving the ball mills the product is discharged to a holding tank. The next step in the process is the circulation of product over the Taste Changer to improve the viscosity and remove off-flavours. The Taste-Changer, a Duyvis Wiener invention, has one of the most important functions in the chocolate production process and creates the unique chocolate taste. In conventional systems this process is done with the conche but with the Taste Changer the same results are achieved within a very short time because of the high efficiency and maximum insensitivity of the device. The eventual difference is surely not recognisable by experts and, more important, not at all by the consumer. Visit www.duyviswiener.nl for more information about cocoa pressing, grinding, butter tempering, powder pulverisation, chocolate and compound processing. Duyvis Wiener is specialised in engineering, producing and installing processing machines for the cocoa and chocolate industry. With its excellent engineering and mechanical team Duyvis Wiener holds an impressive record in providing innovative solutions to the industry in general and the cocoa and chocolate industry in particular. From turn-key plants, integrated processing lines, stand-alone machinery up to the delivery of spare parts and maintenance services. The Duyvis Wiener team is able to provide a technological solution to every problem, paying attention to preventative maintenance and striving to find the best technical solutions and operating practices. Since 2004, Wiener is part of the Duyvis group. Wiener and Duyvis engineers, start-up technicians and process development experts joined forces and are working side by side to guarantee process and product innovations. The integrated laboratory in Koog aan de Zaan, The Netherlands, is available for testing food products in general and cocoa, chocolate, cream and compounds in particular. A database of 25 years of data is available. The combined know-how of Duyvis and Wiener will ensure the continuation of the high quality standard as well as excellent service as you may expect when combining two companies, which have together more than 230 years of experience.

 

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