How to roast coffee beans
To roast coffee, you will need green coffee beans. Without roasting, these beans are undrinkable as they are bitter and acidic. Roasting adds flavours and aromas while also drying and expanding the bean.
You can roast coffee with a pan or grill, in an oven, or with a home coffee roaster. You can also use a stovetop popcorn maker. Although all these methods work well, a purpose-built coffee roaster ensures the best results because it is easier to manage temperatures.
The ideal temperature for roasting coffee beans is between 177 and 260 Celsius. When roasting, constantly stir the beans to distribute the heat evenly.
After 3 to 5 minutes, beans start to crack. This is a sign that your coffee beans are considered a light roast. A light roast is generally achieved with temperatures between 180 and 205 Celsius. With these beans, you get a brew with a light body but higher acidity.
For a medium roast, you should aim for a temperature of between 210 and 220 Celsius. Typically, a medium roast is achieved before the coffee beans crack again. These beans deliver a middle level acidity and fuller body.
A medium-dark roast is achieved with temperatures between 225 and 230 Celsius. Look for patches of oil while the beans are about to hit the second crack. Light and medium roast beans are generally dry. Medium-roast beans have a heavier body with hints of spice.
Dark roast coffee beans need to be roasted at around 240 Celsius. Avoid temperatures higher than 250, which will burn the bean. These beans have an oily surface. When the beans crack a second time, you know they are ready to take out.
Remove beans with a slotted spoon and place them in a colander as soon as they are finished roasting. Move the beans between two colanders a few times to remove the outer skins, which shed during the roasting process. You can store the roasted beans in an air-tight container.