Roasting coffee beans – it’s a kind of magic!

We’ve invited Matt, our friend and an expert barista, to pour his coffee knowledge into our blog. Coffee making has no secrets to him and he’s not afraid to share them!

Coffee roasting is the process by which a coffee buyer will, with the help of science and a bit of black magic, turn raw (or ‘green’) coffee cherry seeds into a browner, tastier and sexier version of themselves.

After the roasting process, these coffee seeds (or ‘beans’ as we know them) will be ready for sale and drinking where they will fulfil their destiny of helping the human population hold their eyelids open.

How does this transformation take place?

With the addition of quite a bit of heat to the green coffee, these seeds will undergo a multitude of radical changes. The high temperatures of the roaster machine (like a big rotating oven) will start to decompose the natural plant colors of these seeds leading to a yellowing/browning effect. The natural proteins are damaged and sugars are formed within the beans.

The core of our now less-green beans will begin to rise in temperature and its water-dense insides will begin to evaporate into a gas. As time continues, temperatures are on the rise! This internal gas will need to escape somewhere, but it can only do so by ‘hulking out’ through the broken-down cell walls of the bean!

This is a moment where in the business it’s call the “first crack”. It is a critical point. The beans appear to have increased in size and are just a few steps away from calling it a day. All activity within the bean after the first crack is now essential to the development of the roast and will have the final say on the tastes and aromas achieved as the coffee is brewed.

The sugars formed during the initial stages of roasting go through caramelization. Acidity levels and origin(al) flavours die out at the cost of added sweetness, but this won’t go on for long. The “second crack” of breaking skin is just around the bend and once you’ve achieved that you can kiss goodbye to anything that was once beautiful about that seed.

Once the mad scientist (also known as “The Roastmaster”) in charge of this process decides that they’ve found the perfect balance of flavour, it is time to stop EVERYTHING. Get those bad boys out of the drum ASAP and cooled off rapidly.

Once the moment of roasting has come and gone, the beans will continue to release gas for a while and their deliciousness days are numbered. Generally speaking, most coffees require time after roasting before they can be made into a drink that maximises their most mind-bending capabilities. But don’t wait too long, fresh is best!