Cocoa processing step by step
Cleaning Cocoa pressing starts with removing contaminations in the delivered raw cocoa like stones, sand, dust, wooden parts, strings, iron parts and other foreign bodies. Bean pre-treatment Next step is a heat treatment to create a ballooning effect in the shells of the cocoa beans before separation of shells and nibsin the winnower. Winnowing (separation of nibs from shells) The pre-treated cocoa beans with their expanded shells, are fed by dosing chute to a pre-sieving unit. From here, only whole cocoa beans pass into the crushing chamber where they are mechanically thrown against an impact surface. The brittle shells break into coarse pieces, and the nibs break apart along their natural separating linesinto large fractions. The broken product is conveyed directly to the sieving and aspiration section. The separation of the shell from the nib, plus the grading of the nib into different size ranges, is achieved by means of an aspiration/sieve combination. The material retained on the top sieve deck, mainly consists of cocoa beans that are hard to break. These are returned to the crusher. AlkalizingWhen required, the nib may be alkalised and de-bacterised in the roaster. Alternatively, the nib can be treated in separate reactor, wherein the nib is penetrated by an alkaline solution, steam and air. With the addition of partially up to 30% per weight of a hydrous alkaline solution, pH values from 7 to 8.0 can be achieved, together with respective changes in colour. - a separate reactor plantis quoted as an option only, since this unit will only be necessary for speciality cocoa powders. Roasting, sterilising and cooling The broken cocoa nibs are dried to optimal moisture content in a roaster. The totally enclosed roasting cylinder, which is externally heated by conduction, allows indirect heating with the exclusion of any combustion residues from combustible gases. Shortly before theend of the roasting phase, the hot nibs are sprayed with water that immediately evaporates under a slight excess pressure, producing a moist, hot atmosphere. This results in a very effective reduction of bacterial count to values of normally < 100 -1000 germs/gram. It is also possible with this roasting method to add alkaline solutions during the roasting process to achieve dark brown to reddishpowder colours. This extends the roasting process. grinding of nibs to cocoa liquor The roasted nibs are grinded in several stages to a final fineness of about 99.5% < 75 µm. First the nibs are pre ground in a beater blade mill. The pre-ground liquor will be further processed for final size reduction by pumping it through several ball mills. After the last ball mill the liquor will be sieved toremove the too large particles which have been slipped through. The cocoa liquor is pumped to the liquor storage tanks from where the liquor can be further processed.
liquor tempering and blocking The cocoa liquor is tempered and packed in 25 kg carton boxes with plastic inner liner. The cocoa liquor is fed to a dosing valve via a pre cooler and a tempering machine. Filling of the boxes is fullyautomatic and supply and discharge of the carton boxes is realised by a conveying system with integrated load cells for exact weighing and filling of the boxes. Cocoa butter pressing In the Duyvis cocoa butter presses the butter is separated from the cocoa cake. This press achieves a high pressing result in combination with good liquor preparation, liquor filling pump and the hydraulic unit. Thetotal pressing cycle can deviated into 3 main steps: • Filling • Pressing • Opening During pressing the butter is separated through filter screens in the counterpots. Butter runs down butter dripping trays into a central butter channel and the butter is collected in the butter discharge vessel. Cakes are dropped in a cake conveyor. As soon as the cakes drop into the trough, the disc pushed them...