How To Roast Coffee.

Posted at 3:08 PM, Friday 18 July 2008 in Roasting - methods

For the uninitiated, the following is an explanation of the roasting process. As I said before, roasting is NOT difficult or technical. As such, I'll give the explanation by using a couple of "layers" - let's call it the Onion Method (with thanks to Shrek) - first the basics, then the guts, then the details. If the details don't interest you, skip them!

How to Roast (layer 1):
> Heat the green beans, while stirring, until they are dark brown. [Seriously, you could follow these instructions and probably end up with drinkable coffee!]

How to Roast (layer 2):
> Heat the green beans quickly, while stirring to ensure that they roast evenly, so that they are dark brown after 15-20 minutes.
> During the roast, the beans will change from green to yellow to orange to light brown and then to dark brown (and, eventually, to black... and then back to orange as they catch fire... but don't go there). The beans will also swell up considerably during the roast.
> When the beans are about almond-coloured, they will emit a cracking noise - the "first crack" (FC). This will stop, and soon a second round of cracking noises will begin - the "seconds crack" (SC). This is approximately when you stop roasting.
> Cool them down to room temperature as quickly as possible.

How to Roast (layer 3):
> Roasting too slow will make the coffee taste flat; roasting too fast will make it too acidic and not sweet enough.
> By increasing/decreasing the heat, you should aim for FC to occur at around 10-12 minutes, and for SC to occur 5-6 minutes later.
> Much of the flavour development happens between FC and SC, so you will need to lower the heat after FC in order to extend the time between the cracks.
> On the other hand, you don't NEED to wait for SC. Once first crack (FC) has finished, the beans can be pulled at any time. Lighter roasts tend to give the coffee more acidity as well as emphasising the bean variety's inherent characteristics. Darker roasts enhance the body, sweetness, and a range of darker, deeper flavours.

How to Roast (layer 4):
> FC will occur as the measured temperature gets to 200-205ºC (internal bean temperature will be lower). SC will occur as the temp reaches around 230ºC.
> Both FC and SC create some heat of their own, so it is important to back off the heat when the cracks occur. Aim for the temp to rise by 4-5ºC per minute between FC and SC.
> Applying too much heat at any time can cause "tipping", where the narrower ends of the beans can get slightly burnt.
> The beans lose around 18% of their weight (in water vapour) during the roast.
> Roasting faster or slower can be done intentionally in order to achieve a different taste. For example, some acidic beans' inherent fruity characteristics can be enhanced by a slightly faster "ramp" to FC.

How to Roast (layer 5):
> CLASSIFIED. ie. I'm not this knowledgeable about roasting, but I'm sure some people could give further advice!


We're planning on making a short video tutorial to roasting sometime soon. We'll keep you posted.