The Sound of First Crack

A Sound that Every Roaster is Finding – The Sound of First Crack

Do you guys like cooking? When the food is cooking on the pan, it usually releases smell, heat energy and even sound. If we fried some food in a right way, we could say it has “Wok Hei” in Chinese. In the previous articles, we discussed that coffee roasting shares the similar ideas or principles with cooking. When we perform a coffee roasting, it will create smell, heat energy and sound as well. When the biggest sound comes out, we will call it the “first crack”.

The Sound of First Crack

What is ”First crack”?

Roasting Coffee“First crack” means the coffee beans are having an obvious sound when it is being roasted in the machine. This sound is like when you’re making the popcorn, or burning the fire woods in a camp fire. In cooking, this is a performance with “Wok Hei”. We know that coffee roasting is actually talking about the physical and chemical change of the coffee beans. When the green beans are loaded into the drum, it will first go through a process called dehydration. In this process, the beans are in the endothermic stage, the growing temperature makes the water in the coffee beans become steam, which means the content of water in the beans are decreasing. When the beans absorb the heat energy more often, the pressure inside the bean is greater than the strength of the bean. the cell wall of the coffee beans will burst because of the expansion in the core of beans. At this moment, the beans crack open a little bit. It will release the heat and the sound energy. This is what we called “First crack”.


Does “First crack” important in coffee roasting?

I would say that the sound of “first crack” is the sound that every roaster will look for. “First crack” represents the physical change of the bean. It also shows the chemical change of the coffee.

Checking Roast

If we talk about this with some scientific or special terms, I’m afraid it makes people a lot more difficult to understand the principle. Let’s talk about tasting coffee as an example. Folks who love drinking coffee may like the fruity flavour in it, while some of them may like the caramel and bitter sweet taste, and some of them may like the floral or tea-like coffee. Why is there such a lot of flavour in a cup of coffee? Isn’t It only taste sour or bitter? Actually, the flavour I’m talking about is the tasting notes of coffee. The creation of tasting notes are mainly because of different weather climate, different growing conditions and different processing method the farmers are using. However, does it mean that a coffee roaster has none of the responsibility for the creation of the tasting note? Obviously, the answer is NO. A good coffee roaster should realise that they have an important rule: to control the roasting process. It is to make sure the beans can show the tasting note with a suitable roasting level and can have the biggest play in a cup of coffee. It’s like cooking, if we give the incredible ingredient to a poor chef, it’s only a total waste.

First CrackDuring “first crack”, the particle of the beans will react with heat energy, release different kind of flavour components (that’s why we taste or smell floral, fruity, etc.), and go through a browning process (that’s why roasted coffee beans are brown in colour). During this stage, the beans are developing its own potential flavour. The smell and aroma are the strongest in this stage. The flavour could have a big difference even there is just a second earlier or later when we drop the beans out of the drum. Therefore, the sensory of roaster should be SUPER sensitive in this stage. And that’s why the sound of “first crack” is a sound that every roaster will look for: it is a reminder and also a necessary element for the beans to develop its own flavour while roasting.

If you have a chance to try a coffee roasting, bear in mind to pay attention the sound of “first crack”!