The way in which green – or raw – coffee beans are roasted will ultimately determine the taste. This makes the roasting process one of the most crucial influences in how your coffee tastes – in addition to country of origin and environment as well as the grind and pour.
Green coffee is reminiscent of earth and grassiness and is softer to the touch than a roasted bean. The temperature and length of the roast will determine final characteristics such as aroma, body (how the drink feels in your mouth), and flavour, all of which intensify as the process goes on.
HOW GREEN COFFEE IS ROASTED
At around 100°C, the beans begin to produce a vapour; as they reach 160 °C they begin to brown. Known as the Maillard reaction, this chemical reaction between an amino acid and a reducing sugar is responsible for many of the emerging flavours. This same Maillard reaction occurs in other food processes – such as the browning of toast or steak, or during caramelisation – and influences flavour and taste.
The build-up of water pressure and gases cause what’s known in the business as the ‘first crack’ – this occurs at around 205 °C. If you continue roasting to 240 °C, the beans become darker and a second crack will occur. What’s a crack? It’s literally the bean cracking slightly, a bit like a kernel popping but not as dramatic; the beans look like they’re dancing, rather than exploding.
It’s during these cracks that roast grades are determined. Lighter roasts come just after that first crack, whereas a medium roast sits somewhere between the first and the second, at around 220°C. Medium-dark sits between 225 and 230 °C, with a dark roast finally achieved at 240 °C.
THE DIFFERENCE BETWEEN COFFEE ROASTS
The flavour of a light roast can be described as tasting like toasted grains, with distinct character. The lower roasting temperatures lend a more acidic flavour – bright and lively – and pronounced characteristics of where the beans were grown, known as its terroir. Beans from Ethiopia, for example, are likely to have citrus notes, whereas beans from Central America might taste more like chocolate; it’s these characteristics that you will be able to taste the most. You might say that a light roast is charismatic in flavour.
A medium roast coffee is a more balanced affair, revealing flavours equally between origin and those that emerge through the roasting process, which brings out the sweetness, gives body, and results in more pronounced aromas. Think toasted bread, nuts, and fruit.
The profile of a medium-dark roast will notably have spices, notes of caramel and smokiness, and there will be some oil on the bean that has emerged due to the higher temperatures. This gives a longer ‘mouthfeel’ or persistence in the mouth.
Dark roast is the most intense of them all, with a pleasant charred flavour that is bittersweet and rich with oils that have fully emerged from the bean. Think notes of charcoal, smoke, and dark chocolate.
HOW TO CHOOSE WHICH ROAST IS RIGHT FOR YOU
Without simply trying them all, it can be hard to know which coffee is best for you. We roast to medium, erring on the side of dark. You could describe it as rich, sweet, and persistent. Our blend has remained the same since the day we started and is a recipe that only our Master Roasters know.
A simple way to think about roasts is this:
- A light roast is charismatic in flavour.
- A medium roast is balanced in flavour.
- A dark roast is intense in flavour.