Roasting coffee

Roasting coffee is an art, and the people responsible for it need considerable knowledge. We taste every coffee after roasting to discover which approach suits it best. Experiments sometimes produce underdeveloped or over-roasted beans, but testing and tasting are essential to learning.

Professional coffee tasters assess flavour and aroma. Information about the green beans, suggested roast approaches and expected flavour notes helps us make an initial assessment and select a starting profile.

Our first roaster

Our first coffee roaster, an AMBEX YM-2, came from the United States. We waited a long time because it was held at the border. We had planned to serve our own roasted coffee as soon as Cafe Borówka opened, but the machine arrived a month later.

We had ordered green beans well in advance, so trials began as soon as it was connected. We cannot claim those first attempts were successful! After a week and many kilograms of under-roasted or over-roasted coffee, we finally established our first roasting profiles.

What is a roasting profile?

Put simply, it records how time and temperature should develop for a particular coffee. Once we establish a profile, we save it under the coffee’s name—for example, an ETHIOPIA profile for Ethiopian beans.

Following a recorded, computer-monitored process helps us reproduce the intended flavour and aroma. Small changes in time or temperature can alter the result, so consistency matters.

Three broad roast levels

• Light: cinnamon to light brown, usually with more noticeable acidity and origin character. The original article used about 205°C as an example endpoint and highlighted the lively, wine-like and citrus notes of coffees such as Kenya AA.
• Medium: a popular, more developed roast with a balance of acidity, sweetness and roast bitterness. An example endpoint given was around 215°C.
• Dark: dark brown, sometimes with visible surface oils, with lower perceived acidity and stronger roast bitterness. Example endpoints were around 225–235°C.

These temperatures depend on the machine and measurement point; they are not universal instructions. Roast level also does not provide a simple, reliable ranking of caffeine per cup, which depends on dose and preparation.

A more detailed roast vocabulary

• Cinnamon roast: very light, cinnamon-coloured beans, delicate aroma and pronounced acidity.
• American roast: darker than cinnamon but still relatively light, often retaining lively acidity.
• City roast: a full brown colour, generally a dry-looking surface and a balanced cup.
• Full City roast: darker than City, sometimes showing the first surface oils.
• Vienna roast: dark brown with more visible oils.
• French roast: very dark, with pronounced roast bitterness.

Any coffee can be taken through different roast levels, but one approach may reveal its qualities more successfully than another.

Roasting and cooling

Once we choose a suitable level and profile, roasting begins. In the setup described here, it took around 12–25 minutes depending on the roaster, batch size and profile. Beans expanded considerably while losing roughly a fifth of their weight, mainly through moisture loss.

Our AMBEX took a 1.6 kg batch of green coffee, yielding approximately 1.2–1.4 kg of roasted beans. At the end, its loud and rather insistent signal—sometimes startling café guests—told us it was time to discharge the coffee.

Cool air then brought the beans’ temperature down quickly. Prompt cooling matters because hot beans continue developing, and slow cooling can push the roast further than intended.

That is all for today. Next time, we will explain what happens after roasting.