There has been a lot of discussion about winnowers here on The Chocolate Life recently. As anyone who has tried to make chocolate at home and then wanted to move up to larger-scale production (e.g., more than about 5 pounds per batch) one of the most difficult machines to try to locate is a winnower to separate the nibs from the shells. Like many aspects of chocolate making, it's not too difficult to find equipment for 5lb batches or 250kg batches or 1000kg/hour, but finding something in between 5 lbs and 250kg is tough.
Elsewhere, someone referenced a $70,000 winnower. Here is a link
to the company that makes it, Bottom Line Technologies. As you can see from the photo it doesn't look all that complicated and it's not really. The real technical challenges come from understanding the mechanics of vibration and airflow necessary to make it work. From what I have heard, Bob and Pam Cooper of The Original Hawaiian Chocolate Factory have purchased one of these to replace their own home-built winnower.
But most of us don't have $70,000 to spend on the all of the equipment needed let alone for a single part of the process.
I spent a lot of time online looking for small winnowers and I ran across a design for a small fan-based winnower
that served as the inspiration for one I built. I spent about $100 in parts (the most expensive components were the fan and the variable speed control) and it was tricky to regulate the airflow to get it to work. In order to work it was necessary to run the cracked beans through a couple of times - the first to get the smaller bits out (low fan setting), then again to get mid-sized bits outs (medium fan setting), and then once more with a high fan setting to get the largest bits out. To make the whole process faster and more efficient I ended up making a set of nested sieves using progressively smaller screens of wire mesh. The big bits stayed in the top compartment and the small bits (the fines) fell all the way through to the bottom. The stuff in the middle was pretty evenly sized and I could get a very clean product in a single pass. A setup like this one can easily handle 10kg per hour or more, especially if you add a shop vac to collect the output (you'll need a way to vary the suction power) and find a way to automatically feed the unshelled nibs into the input.
If you are at all handy and don't mind spending the $100 or so then the one above works a whole lot better than a blow-dryer (which also has the side-effect of leaving enough shell that when you run it through a grinder such as a Champion Juicer you run the risk of contaminating the liquor with salmonella, e-coli, and worse).
A simple way to sterilize small quantities of beans (roasting temperatures are not high enough or long enough to be completely effective) without harming the beans is to use UVC light. Home units look like small wands
and there are larger commercial units specifically designed for sterilizing food products (such as cocoa beans) without harming them in any way.
Sam Madell of TAVA (Australia) posted a photo of one they made
that looks like it is easy to make and adjust as well as being inexpensive to build. I don't know what the throughput of this is, but if you could find a way to funnel, at a controlled volume, the unshelled nibs entering the winnower my guess is that you could get 50kg or more an hour throughput this way. (Any notes on this, Sam?)
Another option is to look for equipment that is designed to clean/sort other types of agricultural products such as seeds and beans. One such is the Clipper Prelude 324
. I have not tested this unit on cacao but it's fundamentally the same design as the $70,000 machine without the dust-collector fan. It would be necessary to play with the sizes of the screens, but at about US$6000, the 324 can process many hundreds of kg per hour. (There is a larger version at about twice the price with more than double the throughput.)
If your throughput needs are much more modest, you might want to take a look at products from CPS Limited
in the UK (click on the cocoa breaker link). One of their winnowers is specifically designed to handle cacao in smallish-quantities - about 25kg/hour - and is priced at about US$800 when I checked a couple of months ago.
What other approaches have people seen or used?