Harry is the head roaster at Specialty Coffee Army, who are based in Mernda. You can buy their roasted coffee beans and ground coffee either online or at Eltham Farmers’ Market (2nd and 4th Sundays). Here he writes about how to select green coffee beans for roasting.
All of the coffee’s flavour potential is held within the green bean and is unleashed during the roast. So, unless these coffee beans are carefully selected and you take the opportunity to tweak the roast and flavour to your liking, you will not achieve a delicious roast.
There are several factors that contribute to the overall green coffee bean quality. It’s essential to recognise these factors from the beginning – when you’re selecting and purchasing.
When selecting the right green coffee beans you will need to consider a range of factors.
Each place has different conditions – soil, humidity, climate, etc – which will have a big impact on the flavour and aroma of the coffee. Also, being able to see which farm the coffee was grown at is usually a sign of a good quality batch.
Generally, higher altitudes means lower temperatures. As a result, there is slower growth which, in turn, allows the sugars to develop more. The coffee beans gain a more complex taste profile, sweetness, and typically more acidity compared to those grown at lower altitude and warmer temperature.
The processing method will have a substantial influence on the final taste of the coffee. The two most popular processing methods are:
- Natural – drying the entire coffee cherry with the seed still inside, usually on raised beds in the sun. This method produces heavy-bodied, sweet, smooth and complex coffees.
- Washed – the seed is removed from the fruit before drying using water. This method produces coffees that are cleaner, brighter, fruitier and more acidic.
You want to make sure that the green beans are similar in size and colour, relatively uniform.
The same colour means that they have been treated and ripened in similar ways, consequently making them reach the same level of roast simultaneously.
Beans of similar size will roast at the same speed.
Selecting uniform green beans is important to achieve repeatable and consistent roasts.
Traceability and ethically sourced
If you, like most roasters and microroasters, do not have the ability to buy directly from farmers, I (Harry) suggest selecting importers with a reputation for sourcing beans in a way that is fair to the farmers and doesn’t harm the environment. The importer should be committed to transparency and provide full traceability of the green coffee.