Sorting it All Out: Counter Culture’s Use of an Optical Sorter for Roasted Coffee

By Timothy Hill

Thinking about the consistency of anything is daunting, whether you are staring at a bag of rice, pondering how it is possible that every single individual grain is almost exactly the same, or thinking about a barista behind the counter pulling espresso after espresso. The topic of consistency is one of those rabbit holes where dipping your toe in could end up dragging you under. It is likely good then that specialty coffee is not just the lack of defects or the presence of consistency.

It is a “specialty coffee” because it exhibits distinct character. It is something, well, special. This is the side of the equation that keeps us—as an industry—sane and focused. But, throwing some sanity (and some grammar) out the window, it is not not about consistency either. Consistency is something we prize. It is something we strive for, something we train for. It is something the company I work for believes in so passionately—we not only stuck our toes in, we jumped in.

The Optical Sorter

What does “jumping in” mean? For us, one aspect has been the implementation of optical sorters for our roasted coffee. Optical sorters are the same technology that rice, beans, corn, grains, and dozens, if not hundreds, of products go through for removal of inconsistencies. These machines use imaging software to calibrate
what the user wants in a product, and also what the user wants out. In our setup, coffee passes through a channel and is inspected by a camera, which will then determine what the air jets will eject out. The jets have the capacity to eject out thousands and thousands of beans per minute.

It is important to note that using this machine for coffee is not actually a new idea at all. For decades, modern dry mills in producing countries have utilized these optical sorters for removing inconsistencies in green un-roasted coffee. However, it is also important to make a quick note on how coffee is a little bit different than most of the other products that get sorted. The difference is that coffee really transforms in the roaster. While inconsistencies might have been taken out in the green un-roasted form, a whole different set of inconsistencies may become noticeable in the roasted product. Export milling can certainly impact the roasted consistency of a coffee greatly, but the size of the beans, the elevation, the variety, and even the moisture level of the coffee can all impact how efficiently the milling can be done. Thus, no matter how good the milling, we have yet to see a coffee that has had a perfect consistency after roasting.

What Are We Sorting?

Optical sorters can sort for a few different features, but most sorters—including ours—are sorting by color and shape. This means that the optical sorters can sort for rocks and other foreign materials, but in our setup the primary purpose is for the removal of quakers. (Quakers are the light amber underdeveloped beans that can show up in a roast.)

In technical grading terms a specialty coffee should not have a single quaker in a 100-gram sample of roasted coffee. This standard is for good reason. Quakers can be flat, harsh, and astringent. Not to mention the flavors themselves are generally a cloying combination of nuttiness and stale un-sweetened grain. On a cupping form, it would not be uncommon for a cup perceived to have a quaker to receive a 2-point deduction on consistency alone. If the quaker was strong enough, it is possible the taster would subtract more. Quakers can be the reason a coffee’s flavors are muddled, and why the coffee’s body feels dry and hollow instead of juicy or syrupy. While all of these characteristics are reason enough to want to take out quakers, it was another realization about quakers that started the idea to sort them out.

The Realization and The Idea

We got the idea to start using an optical sorter on roasted coffee due to Coffee Leaf Rust, a major issue for coffee producers around the world. Since 2009, we have noticed producers—particularly in Latin America—have had more inconsistency in their coffee. In some cases, we have been to farms where we had never seen a single under-ripe cherry go through their production. Yet, when we roasted their coffee, we found quakers. This rearranged our thinking on quakers. If quakers, which we had always believed were just under-ripe cherry, were actually possible even if it was picked 100% ripe and consistently, we were dealing with a different problem. The problem is something that could be much harder to control and something that even the best of farms could suffer greatly from. With this realization, we knew that if we prided ourselves on long term partnerships and the highest quality coffee possible, then we had to find a solution for producers doing amazing work and still struggling with this quality issue.

Implementation and Possibilities

The implementation of the technology was not exactly easy. From the mechanics of operation to the costs, there are hundreds of questions to consider. Questions like: Does roast level impact the sorting ability? Does the type of processing affect the sorting? Does density affect the sorting? With all of those answers being yes, and with all of the quirks and challenges of setup, it begs the question—is it all worth it? For us, the relentless pursuit of quality, and the dream of perfect consistency made the answer easy. The possibilities beyond that, though, answer this question even more resoundingly—and the possibilities may be more interesting than initially perceived.

We believe the possibilities really lie in the coffees that the specialty coffee industry passes over. In some of these lower grade coffees, you can often find super dense high-grown coffee, mixed with under-ripes and less desirable beans. Through this triaging of screen size and grades, great coffees can be lost because of the inconsistency that is found. So, what if you could separate out the quakers and inconsistencies? What if you could find the diamond in the rough? This is the exciting part. This is a new reality where it is possible to pay farmers more for a product that would have otherwise gone to a commercial market, sort it, and have it taste as good—or even better—than beans being sold as specialty, and still deliver that product for less cost to the customer. The possibility of culling these coffees out and discovering something new, while creating value, hopefully challenges our assumptions and the standards of how certain coffees are bought and sold.

Tim BioStarting as a barista in 2002, Timothy Hill has worked his way backward through the stateside supply chain; delivering coffee, bagging it on the production line, and then as a roaster. Today he is the head of quality and sourcing for Counter Culture Coffee based in Durham North Carolina. Much of his focus at Counter Culture is on building supply chains, particularly in Central and East Africa.