Gavin Gam of Aroma Coffee offers a 'how to' on achieving an accurate sample roast.
Sample roasting is the penultimate phase in green coffee grading.
Just short of cupping, it’s the most important part of overall coffee evaluation.
In the last column I went through a measurable checklist when buying direct trade coffee.
Sample roasting was one of the key items mentioned, but it deserves a lengthened explanation to fully appreciate its significance.
Sample roasting is a process I’ve come to enjoy, but it’s also about understanding the shipment of green coffee you’re about to receive, and whether the roasted process will continue to accentuate the bean’s unique flavour profile.
At this point – before roasting – we know what the moisture content of the beans is, the bulk density, and we have an understanding of how the coffee was processed.
Now it’s time to apply all of this knowledge in a sample roast and cupping so further evaluation can take place.
It’s important to nominate one particular person, who I like to call “the identifier”, to accompany the sample all the way through into the cupping phase.
Protocols create consistency and this is crucial when you get to the cupping phase.
All coffees will be cupped blind to rule out any preconceived strengths or weaknesses in the coffee, so at this stage an alpha/numerical system should be devised so the coffee can remain anonymous.
If you stuff your labels up the whole process can be ruined.
I recommend using a 100-gram sample for the sample roast. Keeping your batch sizes consistent means it becomes easier to roast, and you eliminate any variables.
It’s very easy to determine your percentage weight loss from roasting. Weigh your coffee after it has totally cooled, and the difference is your percentage weight loss. Usually for cupping 16 per cent is a sign of a well-roasted coffee, so if we use a 100-gram sample, we get out 84 grams and 16 per cent weight loss.
It’s time to warm your roaster before unleashing its power on the beans.
To read the full 'How to' from Gavin pick up the December issue of BeanScene Magazine - subscriber here