There are many factors to take into consideration when roasting a new Coffee. A Coffees region, altitude, moisture content, processing, bean size and density all influence how that Coffee will go from Green to Brown. In this Post we are going to talk briefly on Processing.
There are lots of ways that a Coffee can be processed at the farm:
Natural
Washed
Honey
Carbonic Maceration
Anaerobic
Supernatural
And many more continue to emerge. Here are the main processes and how to approach them when roasting.
Natural
Natural Coffees are dried with the cherry still attached to the bean and then removed mechanically. This process is used where little water is available and often results in a greater variance in bean size. For this reason, natural coffees often need a little less heat and a little more time for sugars to be converted and uniformity to be achieved during a roast. The other tricky thing about Naturals is that they are prone to take off (raise temperature very quickly during First Crack) which leads to a ROR flick and a loss of sugars and flavours.
Washed
Washed Coffees are processed to remove the mucilage by washing with water before drying. This means that there is less chance of something going wrong during drying and that bean sizes are more likely to be uniform. Because of the washing process, flavours are more balanced and cleaner. Generally washed coffees are more forgiving as they can take higher temperatures and don’t flick hard like Naturals around FC. As a result they are a great place to start for new roasters.
Honey
The Honey process is a variant process which combines the Washed and Natural process. The Cherry is removed and the coffee is dried with the mucilage (Pulp) still left on the bean. As a result more sugars are present which makes for sweeter coffees. These coffees can take a bit more heat than naturals but still require careful management as they can take off. A slower roast will help all those extra sugars to caramelise and convert. Do this either with higher airflow or using a little less heat. Personally, I (Tim) find this processing the trickiest to nail but that might just be me!
CM/Anaerobic/Supernatural
Although these processes vary, they all entail the green coffee undergoing further fermentation with yeast to intensify fruit flavours and sugars. The extended processing and fermentation mean these coffees are prone to roast faster and develop quicker. We have found that after First Crack these coffees need to be dropped a little earlier than what you’d expect and will often appear lighter on the outside than they actually taste. In one sense, these coffees are a bit fussy to roast, but in another, they are easy to get great flavours of because of the intensity the processing brings out.
While processing isn’t the only thing to consider when roasting a new bean, it is one of the more major factors to take into consideration. Keeping these basic tips in mind will help you get the best out of roasting that great new coffee you want to try out.