Roasting is a pivotal stage in a coffee's creation. Transforming raw green 'berries' into dark brown beans, through the careful application of heat.
By roasting the coffee, a chemical reaction takes place that draws out its flavour and aroma. Roasting level varies from light to dark, depending on how long the beans were roasted for and at what temperature.
Light Roast Coffee
Beans that are lightly roasted will have a light brown colour and appear dry (due to a lack of oil). They will have been heated for a short amount of time, at a lower temperature - typically around 195 to 210°C. This is an important range to remember, as coffee begin to 'pop' at 195°C (similar to popcorn kernels) - this is known as the 'first crack' and is caused by built-up steam and CO2 being released from the bean.
How does light roast coffee taste?
As light roast coffee has been exposed to less heat, more of its original characteristics will remain. This includes higher levels of acidity and less bitterness, which results in more bright, tangy flavours - such as citrus (lemon, orange, lime) or fruity (berries, grapes, etc) notes. You may also be able to taste floral or tea-like notes.
Light roast coffee has a lighter body, resulting in a smooth mouth-feel with less of a lingering taste (due to fewer oils).
How to brew light roast coffee?
Light roast coffee lends itself to Pour Over or filter coffee brewing, as they help highlight the often complex and nuance flavours. We recommend trying lighter roasts without milk, as it can make it harder to taste the subtler notes.
Medium Roast Coffee
Medium roast coffee will appear mid-brown in coffee and feel dry to the touch. The beans will be heated to around 210 to 220°C - which lies after the 'first crack' but before the 'second crack'. This higher temperature combined with longer roasting time, breaks down more of the acidity in the beans so they are not as 'bright' tasting as lighter roast coffee.
How does medium roast coffee taste?
Overall, medium roast coffee is more balanced and smoother in flavour. It has a moderate level of acidity and bitterness, with more sweetness developing from a longer roast period. This is often characterised as chocolate or caramel notes, with a toasted or nutty taste that is enjoyed by many. It has more body than lighter roast coffee, with a slightly thicker or heavier mouthfeel.
How to brew medium roast coffee?
Medium roast coffee is highly versatile and can be used in a variety of brewing methods. We recommend AeroPress or Pour Over brewing for coffees with more fruity notes, and Cafetière or Moka Pot brewing for coffee with more depth.
Dark Roast Coffee
Beans that are darkly roasted will have a deep brown colour and appear slightly shiny, due to higher levels of oil. To be considered dark roast, the beans must be heated to above 226°C (typically around 230 to 235°C) - where the 'second crack' takes place. Similarly to the 'first crack', the beans will 'pop' which creates a quick, cracking noise and signifies the breakdown of cellulose in the coffee.
As dark roast coffee has undergone the most chemical change, it will lose many of the intrinsic characteristics of the beans (such as acidity) and gain more qualities from the roasting process itself (such as bitterness and body).
How does dark roast coffee taste?
Dark roast coffee has a bold taste and strong aroma. It has low levels of acidity, with a higher level of bitterness. Dark roasts are often described as nutty, earthy, spiced or smoky, with dark cacao or treacle notes. They create a full-bodied coffee, with a heavy, almost syrupy mouth-feel that lingers.
Dark roast coffee is popular in southern Europe, including Italy, Spain and Greece, where espresso style coffee is a cultural cornerstone. It is typically used in a Moka Pot, to brew rich, strong coffee that can be enjoyed as an single shot or with milk in a macchiato or cappuccino.
How to brew dark roast coffee?
Dark roast coffee can be used in a variety of brewing methods, including Cafetière, Cold Brew and Moka Pot. They are probably most widely associated with espresso coffee, where their strong, bold flavours shines in a small, shot serve. If you have a Bean-to-Cup Coffee Machine, dark roast beans are a great option.
If served with milk, the sweetness of the dairy can create a pleasing balance and mellow some of the harsher, bitter notes.