What Is A Roast Curve And How Does It Make My Coffee Taste Better?

The roast curve is an element at the heart of our quality control program. It allows us to stay consistent and ensure that every batch is roasted to the same relative specifications every time. To put it another way: we're not relying on our 'intuition' or 'gut feelings' to make sure your coffee tastes as good as it can possibly taste.

Mastering the roast curve is a life-long pursuit for many roasters. With the prevalence and affordability of software, it's amazing that more roasters don't use it. The main insight that is gained from using computer software to visualize your roast is seeing how evenly heat is being applied to the coffee beans. The more even the heat is applied the better the flavor is developed and roast defects diminished. 

Using the example of baking bread you can imagine, if heat is applied too quickly the bread could easily be cooked on the outside but raw in the middle. Or if it is cooked too slowly the crust could never fully develop and the bread could end up dense and unpalatable. The same is true for coffee. It is all too possible to roast coffee unevenly imparting negative flavor characteristics. 

Using computer software and multiple digital probes placed throughout the roaster we are able to visualize in detail what is happening within the roaster in realtime. This allows us to consistently roast our coffees taking into account variables like outdoor temperatures, humidity, bean density, moisture content and batch size, all of which can drastically effect how heat is applied throughout the roast. For you drinking coffee at home, this means sweeter coffee and better cup clarity from coffee to coffee and batch to batch. 

Talk like pros:

If you'd like to dive deeper, here are some important terms related to roast curves that will help you find your answers: 

ROR (Rate of Rise): the rate at which the coffee bean is changing temperature within the roaster over time. Expressed as (current temperature minus previous temperature)

BT (Bean Temperature): the temperature of the bean mass inside the roaster

ET (Environment Temperature): the temperature of the air as it exits the roaster

Development: usually refers to the time between first crack and roast end when the majority of the maillard reaction (think: flavor development) takes place. Sometimes expressed as a percentage relative to the total roast time. 

Charge Temperature: The temperature at which the batch begins, green coffee enters the heated roaster. 

First Crack: The point at which heat and moisture have built up with in the bean to the extent that they begin to audibly 'pop' and 'crack' inside the roaster.