Coffee roasting is actually tricky, but it’s not rocket science. At first, you’d think all you need to do is put green coffee into a roaster, crank up the heat and turn them brown. That couldn’t be farther from the truth when it comes to roasting coffee. Coffee processing methods, including washed, natural, or honey processes, along with density, will impact your roast profile. These, along with some other factors, can really affect how you can or should roast the coffee. Unfortunately, not all coffees are equal, and they each need their own unique formula to bring out those naturally delicious flavors.
Why Our Coffee Tastes Different – Our Coffee Roasting Method
At Path Coffee Roasters, coffee roasting is both an art and a science. Our evaluations and choices related to flavor development make up the art. The science is how to achieve it. Obtaining a steadily declining ROR (Rate of Rise) is integral in producing coffee that is fully developed and sweet. Scott Rao, a well known and respected coffee roasting consultant, noticed that over thousands of roasts and many tastings, the best coffees were always ones where the ROR fell on a steady decline and avoided what he termed the “crash” & “flick.”
The image above shows a roast where there are an obvious flick and crash. The crash produces a baked coffee or one devoid of profound richness and structure, and the flick can impart roast flavors that we’re looking to avoid when roasting coffee. While the bean temperature creeps upward, the ROR curve should hit a high point early on, and then steadily decline till you finish your roast. Currently, we roast 20 to 40-pounds at a time, depending on the coffee. This allows us to be more consistent as we sometimes roast the same coffee over many months.
(As you can see above, the profile demonstrates a steadily declining rate of rise.)
Our roast days begin by weighing out green coffee first thing in the morning to cover our current orders. We like to roast our darkest coffees first so that, along with our usual warm-up, we achieve a thermally stable roaster. We need to make sure that our roaster is hot enough so that any coffee we put in doesn’t affect the thermal stability. Once our roaster is warmed up, typically around 45 minutes, it cools down to 50 degrees below our charge temperature (the charge temperature is the temperature we choose to start our roast at). Once the coffee enters the roaster, the thermocouple now immediately descends hundreds of degrees to around 180 F. At that time, our coffee and thermocouple begin to equalize, and the temperature begins to rise up. Gas is applied at this time to start driving the roast, and as the roast progresses, we being to pull back on our gas to develop our roast profile.
Each coffee requires a slightly different profile to maximize its natural flavors. This might mean our charge temperature is adjusted because our batch size is 20 vs. 40-pounds. We might use more gas upfront than at other times and so on. Regardless, our goal is to produce a coffee that is full of flavor, mouth-filling, balanced, and easy to extract when brewing at home, in the office, or at your cafe or restaurant.
Sugar browning is a crucial element to our style of roasting. We aim to source and provide sweet-tasting coffees. Coffee flavor with form and structure must be coaxed out by roasting. Toward the end of each roast, we start using the tryer to evaluate the smell and shade of the coffee. Once we’re happy, we discharge the roaster, and the perfectly roasted coffee falls into the cooling cart, where it cools down over the next few minutes.