Roasting is actually quite a scientific chemical process. This is where the acids, aromatics and other flavour components of the coffee are developed and manipulated, bringing out the desired flavours and enhancing the origin characteristics of the bean. It is both a delicate art and a fierce science.
But we’re not going to get too technical here. There are four main ways that roasting affects the flavour of your coffee.
- Burns off acidity
- Develops aroma
- Develops body
- Brings the oils to the surface of the bean, releasing the naturally complex flavour of the coffee.
Put simply, the darker the bean is roasted, the less acid it will have, with stronger aromas, fuller body and a more complex flavour. However, this is only true to a point. Excessive roasting will result in the loss of flavour and aroma, to be replaced with bitterness and ash.
This is of course an over-simplification of the process. Coffees of different origins are suited to different roast styles, and it is the role of the roaster to balance the origin and roast flavours to make the most of the existing qualities of the bean.
There are a number of different terms used to describe roast styles, but they can be inconsistently applied. You may have heard lighter roasts being described as “City Roast;” then “City+” and “Full City” as they get darker. Vienna and French Roast levels are respectively darker still, and starting to lose the origin characteristics of the coffee.
At Black Matter, we cup obsessively to perfect the roast for each of our coffees, customising to your preferred brew. Our single origins are available in two different roast styles – filter and espresso.
Espresso coffee is generally served with milk (your flat white, cappuccino and latte), which changes the acid balance. The coffee needs to be stronger to cut through the milk, and so is darker roasted. If you drink your espresso without milk, you might prefer a lighter roasted bean.
Filter coffee is not served with milk and so can be lighter roasted to allow more of the origin flavours to shine through. This preserves the acidity in the bean, producing that sweet, sparkling, complex taste that you expect from filter coffee.
This article provides quite a high level explanation of how coffee roasting levels affect flavour. If you’re after more details please leave a comment below, or get down to the Black Matter roastery for a chat with Tristan – he lives for this stuff! Just don’t say we didn’t warn you…