What is Development Time in Roasting?

Why use “first crack” to judge the beginning of development time?

The “first crack” itself points to a simple physical phenomenon – the bound water hidden deep in the cells of the green beans, after being heated to a high enough temperature, evaporates violently and flushes out the coffee beans, which is similar to “peeling melon seeds” “the sound of. It is almost not directly related to any chemical reaction. There is neither “a certain reaction happened because a certain reaction happened”, nor “a certain reaction happened because a certain reaction happened”, it is just a bursting sound. But interestingly, there is a lot of evidence that the point at which coffee beans transition from an “endothermic state” to an “exothermic state” during roasting happens to be near the first crack point.

Therefore, although the first detonation itself has little to do with chemical reactions, it coincidentally becomes a “very suitable signal”. Using the first crack as a starting point for development time, while not objective, is still reasonable, using the period from the first crack to the end of the roast to represent “development time”.

Development Time = In coffee roasting, what is the use of development time after the first crack to the end of the roast?

The development time is very general. In the traditional and customary concept, the development time is regarded as an important means of “flavor formation” and is adjusted and controlled by people. When encountering insufficient development, there are still many techniques and theories that tend to “reduce the development time.” The temperature rise rate (RoR), extends the development time” to solve the problem.

The role of development time should be understood from two aspects, namely the chemical level and the physical level; since the development time is widely understood as a means of “flavor formation”, we should first look at the changes in the chemical level from the chemical level. In the final analysis, it is the decomposition and synthesis of substances under specific conditions. In coffee roasting, it represents the final color and flavor of coffee beans.

With the update of modern coffee knowledge, it is certain that the chemical reaction of coffee beans has already started during the roasting process, rather than starting after the first crack. The saying “development time = flavor formation” is no longer rigorous. Or to be precise, “development time is not the only way to form flavor”. When discussing “chemical change” and “flavor development”, we should look at the roasting process with an overall vision instead of just discussing “development time”.