Coffee knowledge | what exactly does "clean" mean in coffee roasting?

How to understand "cleanliness" in baking

In the coffee roasting class, I kept talking about how to find "clean" roasting, which is actually the most direct description of the preparation of different drinks and the criteria for judging the coffee beans used for production, so students always ask me, what does "clean" baking mean? Today I would like to explain it in a more specific and visual way through this article, because when it comes to coffee, we must be able to understand the importance of "cleanliness" in different areas of the coffee industry.

The so-called "clean" roasting means that the coffee flavor and aroma that should be reflected based on the origin, variety and processing characteristics of coffee beans are relatively completely preserved through roasting. As we all know, different degrees of roasting will produce different chemicals, thus making the same batch of coffee beans show different flavors. Chemical elements at different stages are produced in different temperature ranges, which means that the more we understand the internal structure and chemical composition of raw beans, the more we can control the formation of flavor.

Generally speaking, if the temperature is not enough, the organic chemicals used to transform flavor and aroma cannot be fully decomposed, then chlorogenic acid will be maintained at a high level, that is, the astringency of coffee, the taste of grass or grain, and the sour taste; at the same time, if the roaster is overheated, the risk of forming a dry distillation chemical flavor will be increased, that is, rubber, smoky, bitter, spicy and charcoal burning taste will be more prominent. Sometimes, rapid baking at high temperature will result in the result that the outer surface of the bean is scorched but the central part is underbaked, in which case the two problems will occur at the same time.

If you can ensure strict compliance with raw bean sample baking standards, and have mastered mature cup testing techniques to make adequate preparations for "clean" baking, then the next thing you need to do is, try to balance or control the variables of all baking tools: speed, firepower, wind speed, weight, and use the right temperature at the right time according to different raw bean varieties and handling methods.

I hope the above explanation can make the concept of "clean" baking clearer.

James Craig / tr. by Phil Newell)

(two Australian baking champions)