The Lehmann cocoa bean multi-step cleaning system from the Royal Duyvis Wiener group is suitable for cocoa beans, hazelnuts, peanuts, almonds, coffee and various other products. The system is complete with a double vibrating screen to separate over- and under-sized product. It also includes an aspirator to remove dust and other light material such as strings and leaves.

The cocoa beans are then moved through a destoner to remove stones that are similar in size to the beans or nuts. Other foreign materials such as wood, paper, strings and sand will also be removed. The Lehmann CR Cocoa Bean Destoner can be fitted with an optional magnetic separator or metal detector for the removal of metal parts that might have found their way into the product.

Our continuous roasters are adjustable to process any kind of bean type and origin.  The systems are also designed for 24/7 production and require very little maintenance.

Continuous Bean Roasting

The Lehmann “shell-pop” pre-roaster from the Royal Duyvis Wiener group is uniquely suited to pre-treat whole cocoa beans so that optimum yields are achieved during the winnowing process.

In our gentle, yet efficient continuous cocoa bean roasting system, the shell protects the nib from being over-roasted, ensuring that all flavor components are retained in the nib. The beans pass through the roaster by gravity and are captured in layers.  In each cycle, one small batch gently tumbles to the next level below.  The roasting air passes through each layer from the bottom of the system to the top. Every bean receives the same amount of hot air, allowing every bean to be roasted equally and very gently.

Due to the unique ‘counter flow’ principle the beans are very gently and evenly heated, preventing fat migration and ‘sweating’ of the bean. This unique gentle process causes moisture to evaporate from the inside of the bean resulting in a ‘popped’ shell that is loose from the nib inside. This allows the breakers on the winnower to run at slow speeds because the loose shell is very easy to remove from the still ‘rubbery’ nib. In turn this leads to excellent nib-in-shell and shell-in-nib figures.

KOCOTEK offers the Lehmann ‘DBF’ Winnower with unique cocoa bean breaking and winnowing technology from the Royal Duyvis Wiener group. Lehmann’s sophisticated winnowing systems use multiple breaking and sieving stages to gently crack the cocoa beans and leave the nib pieces as large as possible.  Capacities range from 1 up to 8 metric tons an hour.  The systems are designed to process cold, roasted or pre-treated beans.

The frequency controlled rotation speed of the breakers increases from one stage to the next, with broken beans sorted between each breaking stage. Because of the multi stage breaking and sieving technology each cocoa bean receives just enough energy necessary to break the shell resulting in excellent shell-in-nib and nib-in-shell figures.

All sizes of nib and shell run through vertical winnowing ducts where the PLC controlled airflow rates take the lightweight shell up, and the heavier nibs fall onto the transport system below.

Nib Alkalization (or “Dutching”) takes place before roasting.  The Lehmann BNA alkalization reactor from the Royal Duyvis Wiener group treats nibs with a moisture content as high as 35%.  PH values of more than 8 can be achieved and high pressure and absolute vacuum can be applied during the alkalization process. This, combined with the superior internal mixing technology, ensures perfect and controlled color and flavor development.  After the alkalization step, the nibs need to be roasted.  Depending on the recipe the alkalized nibs need to be processed in our continuous roaster type ‘KR’ or batch drum roaster type ‘BR’.

The Lehman BNR Batch nib roaster consists of a gently rotating vertical drum. The product inside the drum is gently heated through radiant and convection heating. The entire process is PLC controlled so that specially designed roasting curves can be consistently repeated. Additives can be injected into the drum during the roast, even some mild alkalization steps can be executed at the beginning of the roasting process. A nib sterilization step is part of the roasting process. The integrated cooler has a ‘live’ bottom so that the entire batch is cooled efficiently to keep control over the roast.

Continuous Nib Roasting

The advantages of the Lehmann continuous nib roasting principle have proven its value to the cocoa and chocolate industries for many years.  It is an excellent roasting method due to low energy consumption, flexible flavor development and excellent color development of the end-product.

In the continuous nib roasting system, the pre-dried (and sometimes also alkalized) nibs are fed to the roaster.  Small batches of nibs are all treated equally due to the gentle turning of the layers.  The result: a very uniform flavor development.

Even high acid and non-fermented beans can be upgraded to a less acidic and more cocoa flavored product.  Due to a low roasting temperature the exhaust air has a low concentration of odor.  The nib roaster has a cooling section to bring the nibs down to the ideal temperature for liquor grinding.

The Lehmann Sterilizer type KS generates superior germ reduction, providing consistent total plate counts below 500 cfu per gram.  The prevention of moisture absorption ensures that all flavor components remain within the beans.

The hot cocoa beans are transferred from the roaster directly to the cocoa bean sterilizer; making the sterilization process more energy efficient, and significantly reduces the risk of cross contamination.

During the sterilization process the cocoa beans also ‘puff up’.  This means that the shells are also easy to remove from the nib, aiding the process of breaking and winnowing and generally improving yield numbers.  Compared to other systems, sterilizing hot beans saves a significant amount of energy and retains the original flavor profile of the bean.