What exactly is coffee roasting?
Coffee roasting is the process of heating coffee cherry seeds in order to enhance aroma and flavor and, ultimately, solubility. The rate of solubility of compounds in a specific roast is critical to achieving the desired extraction via temperature, time, and grind size. It’s the coffee geeks’ “unifying theory.”
To achieve solubility, this coffee is roasted, typically in a commercial roaster that is “a cross between a pizza oven and clothes dryer.”
What is a coffee tasting wheel?
In a coffee tasting wheel, it can be seen that the right side shows the progression of flavour compounds that develop as the roast progresses from lighter to darker – with lighter roasts exhibiting more acidic qualities (citrus, malic acid, and apple flavours), medium roasts exhibiting nut and chocolate qualities, and darker roasts eventually turning to carbon. A chart of coffees ranging from light roast to very dark roast is provided below. There are numerous potential technologies that will enable roasters to understand these “colours,” but Agtron is the 800-pound gorilla. It’s a spectrophotometer that measures the relative light absorption of the roasted bean’s surface. Most commercial roasters not only have automation to repeat a specific roast profile, but almost all have a “light” that allows these artisans to precisely measure roast development.
What happens to coffee after it is roasted?
These roast profile areas occur along a temperature spectrum that is unique to each bean based on varietal, region, and altitude. All coffee, however, will eventually go through five distinct stages:
- Yellowing or drying
This is a critical stage because the initial moisture content of the beans determines the overall batch time; this is the phase that will determine the overall batch time. It basically lays the groundwork for the rest of the stages because it determines how hard or soft, fast or slow your roast is driven into first crack and beyond.
- Reaction of Maillard
It is the coffee’s first “browning.” This reaction serves as a catalyst for the formation of many of the 1,000 volatile chemical compounds (compounds that easily evaporate in air and thus contribute to the aroma of coffee) produced during the roasting process. This process is also closely related to the aroma of baking bread. Both are equally delectable.
- The First Crack
While the early roasting phase is all about heat acting from the outside in on the coffee bean (endothermic), “first crack” is the first part of the exothermic reactions, where pressure from moisture evaporation and heat builds up inside the bean and begins to break it down from the inside out. It makes an audible sound, similar to popcorn popping. However, unlike its buttery cousins, it rarely causes cracks or explosions.
- The second Crack
While it’s no longer “cool” for mustachioed millennials, darker roasted coffee is sometimes roasted through a second crack, which is nearing the end of the breakdown process.
It refers to the complete breakdown. Hoxton coffee roasters provide us with best roasted coffee.