Come over to the dark side, Luke. A good line in Science fiction, not so hot (pardon the awful pun) when you are trying to roast artisan coffee. Asking for a dark roasted coffee is probably not answering the need or the idea that dark coffee roasting is supposed to address. Asking for a dark roasted coffee is tantamount to asking for an over-cooked loaf of bread. Here is the Truth about roasting coffee.

Let me explain…

First ask yourself a question – is strong coffee necessarily bitter?

Different coffees have different terroir. Our goal as roasters is to highlight these intricacies while maximising the flavour potential. Ending up with something that tastes good.

As a particular coffee goes through the various stages of roasting, so the flavours, features and nuances build, develop, and eventually burn off. How far each coffee should go is a factor of incredible complexity. Essentially under-roasted coffees are astringent tasting and over-roasted coffees become bitter.

The coffee actually pops a bit like popcorn. It gets complex, as there are two pops, or as we call them cracks. At first crack, the coffee, if stopped there, would now just be tasting like coffee, as the green coffee beans (pre-roasting we call them green beans) taste of uncooked pasta. Through the Maillard reaction, starches in the bean caramelise and flavours develop. Taking things too far causes those sugars to decompose in a pyrolytic process and all is ruined. This can be a major cause of bitterness.

This, however, is only a small part of the puzzle. There are component elements to a coffee that are affected in parallel. The body, or mouthfeel of the coffee, follows a similar path, as does each flavour nuance. So, a coffee renowned for an elegant, blueberry aftertaste, may lose that essence if roasted 1°C too dark and of course, it may not have developed 2 °C earlier!

As a rule, our job as roasters is to follow the flavour. In my opinion, and that of most artisanal roasters, the goal is to allow the coffee to tell you. Each coffee is an agricultural product that is a potential expression of its terroir. When roasting coffee the roaster has to find the ‘sweet spot’ and nail that flavour potential. Bitterness is a byproduct, not a goal. Roast too dark and it is merely burned, loses body and any subtlety that may have been there.

Generally, the zone for correctly roasting coffee is seldom dark and oily – it is just as seldom, a cinnamon colour. If you see visible oil on the roasted coffee bean, it has either been roasted months ago and is stale or it was over-roasted. Note this does not apply to decaf!

In summary, too light and the coffee will be dry and astringent, even unpleasantly winey – too dark and it will be bitter, light and burned. It is also worth noting that the difference between the one extreme and the other is often very subtle and not obvious to the eye.

One more factor for mother time, just as important as how dark the coffee was roasted, the speed it was roasted at can have a dramatic effect. In order to get the best of some of the world’s most incredible beans, one has to slow down parts of the roasting process…

I love roasting on vintage Probat Roasters. They had good old cast iron drums in the old days. Take one decrepit vintage Probat, rebuild it from scratch and add some modern electronics and gauges, and voila, artisan roasting.

Let the force be with you. Use this helpful list to find our Best Coffee Shops in Cape Town

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