How coffee is roasted
How coffee is roasted. Firstly, we need to look at where coffee comes from. The beans that we love to grind and put in our favourite drink are actually the seed of a fruit. The coffee fruit. A coffee plant when growing produces fantastic fruits, that when peeled back leave behind a green seed. This is the coffee bean.
So, when we look at how coffee is roasted. We take the green beans from the plant and put them through a rather specific roasting process. Dependent on what the bean is intended for, for example, a bean that is well suited to espressos, depends on how long it is roasted for.
In a commercial setting, the coffee beans are put into a roaster which has been pre-heated to around 240 degrees. The roasting process takes around 12-15 minutes to complete and they have moved around during the roasting process. Whilst the coffee beans are being cooked they actually generate their own heat, this causes them to expand. Once they reach a point where they cannot take on any more energy the reaction becomes exothermic. As the coffee gets to this stage we start to see the browning of the beans that we recognise as the roasted bean. This is actually created due to the natural sugars inside the bean caramelising, not actually a burning of the bean as you would expect.
When roasting the ‘first crack’ takes place, this is a crucial stage as a bit like when you are heating popcorn in a microwave this is a sign the bean is ready. This is now time to reduce the heat and start the cooling process.
The cooling process is a slow one where the beans are rotated and allowed to cool of their own accord.
One thing that is worth mentioning is a coffee bean can be too fresh, once it has come through the cooling process it can still contain a large amount of gas within the bean from the roasting process. Whilst it is fine to use like this you may notice a slightly acidic taste. It may be worth leaving around a week after the roasting date to get the optimum taste from your cup of coffee.
Are coffee beans edible? Check out another of our FAQ’s to find out!