Why are cocoa beans winnowed? Cocoa beans have an outer shell, but it is the inside of the bean, or nib, that is used in the chocolate-making process. The process of removing the shell from cocoa beans to obtain the nib is called winnowing.
There are several options for separating shell from cocoa beans, but the primary consideration must be the nature of the beans themselves. Cocoa beans are high fat and fracture readily, especially when cool. It is best when breaking beans to keep the shell pieces as large as possible for easy removal, and to minimize nib fines. The fines will adhere to the winnower surfaces causing build up. This can be a problem during prolonged processing if the machine surfaces are not easily cleanable.
Cacao Cucina® winnowers include a bean breaker designed specifically for cocoa beans. The breaker speed and breaking pressure are adjustable to allow for optimizing the size of the broken shell and nib pieces. The breakers are rugged, all stainless construction and can be easily accessed for inspection or cleaning.
After breaking the beans, the separation of the shell from nib is first accomplished by a vibrating/conveying action and then by vacuum removal of the shell. This has been the method settled on by major manufacturers for generations. The amplitude of the vibrating action, as well as the placement of the vacuum pick-ups, are critical. Both are adjustable on our winnowers.
The first screen in any of our winnowers is always an oversize screen that allows the operator one final inspection point for sticks, rocks, and debris. Oversize material can easily be fed back into the breaker.
With experience, an operator can also get a good feel for how well the beans are breaking, and whether or not they are too warm or too cool. Cocoa beans typically break the best when they are slightly warm after roasting, and before the cocoa butter sets up. Breaking the beans warm can help to minimize fines. However, if the beans are too warm, they can be too soft and “gummy” to break efficiently.
The final winnower product screens facilitate the “layering” of the beans and shell as they pass under the vacuum pick-ups. A single layer of mixed nib and shell material is best. If the shell is trapped under the nib, it cannot be vacuumed away.
Due to the fracturing nature of the nib, the screens require periodic raking to prevent blinding. The Winn-15 and Winn-45 winnower models are raked manually. The Winn-150 includes pneumatically driven screen rakes.
For the Winn-45 and Winn-150 models, the fines material is collected separately from the larger nib and shells. This material can either be discarded or used, depending on its condition. The Winn-15 has a separate vacuum pick-up that vacuums the fines with the shell. This pick-up is removable if the operator wants to collect the nib fines separately. The Winn-45 has a separate discharge chute for fines.
Cacao Cucina® winnowers typically yield 75%-80% good nib from the roasted beans fed into the breaker, with less than 1.75% shell and less than 1% fines. Bean origin, bean size, bean shape, breaking temperature and operator efficiency will have an effect of final yield.