The First Crack When Roasting Coffee

Vietnamese Coffee Exporter

The initial bang during the roasting of coffee is frequently referred to as the “first crack.” However, labelling it a “boom” makes it simple to get distracted and believe it is simply the sound of a roasting oven. Contrary to popular belief, coffee beans come in a wide variety of colours, flavours, and structural configurations. You can gain insight into the final flavour and flavour development in the roaster by understanding this stage of the roasting process

The first crack is a heat-radiating reaction – and can be briefly described: Coffee beans release heat (energy) in the form of steam and carbon dioxide. Seeds will double in size and remove most of their silver crust, but there is still no oil on the surface (according to perfectdailygrind).

As well as checking for colour changes, roasters should pay attention to other signs – such as puffing or the “explosion” of the grain.

What is “First Crack”?

The first crack is what people call the first explosion during coffee roasting. But the way to contact ‘explosion’ is easy to distract, so you think it’s just a sound in a roaster. Although, in fact, there are many changes in the colour, taste, and structure of coffee beans. It’s not just the sound (see also the coffee roasting process)

The first crack(cracks” when roasting), which often sounds like a popcorn explosion, is when the coffee beans begin to reach the stage of being packed for use. So the first crack is when the coffee beans start to approach the ability to brew. In theory, coffee experiences two “cracks” when roasted and throughout the roasting process from light to medium, and roasted coffee will end up somewhere between these two “cracks”.

First crack
First crack

The microstructure of coffee beans is relatively organized and dense. When roasting coffee beans, the creation of steam and carbon dioxide (CO2) increases the pressure inside the seeds, forcing the cell wall – the structure from their cellulose to expand. A few minutes before the first crack appears, the coffee beans will hatch enough to start releasing the silver crust (or husk, which is trapped in the folds of the crack between the seeds). When cellulose can’t stretch further, cracks form inside the particles on their surface, pushing steam and gas out roughly, making the noises we call “First Crack” coffee cracks.

One point to note is that if the first crack represents the release of pent-up steam in the coffee beans, then the second crack is the release of the pressure generated by CO2 – this problem is more specifically presented in the physical variations of the roasting process.

How do you recognize the first crack and the second crack?

It’s entirely based on your hearing and observation of the structure of the roast coffee beans. This variation is like popcorn only when the coffee beans are hot enough and the water in the seeds begins to evaporate. Moisture accumulates and then increases the pressure inside the grain, making the coffee beans crack and burs.

The period from the start of the first crack to the end of the roasting process will account for 20-25% of the total roasting time. In other words, when the coffee goes through two-thirds of the roasting journey, it explodes for the first time, which will vary slightly depending on the desired level of roasting –(Scott Rao, The Coffee Roaster’s Companion,2014)

Always observe the sea changes in colour, incense, and structure and listen to the sound from the home coffee roasting.

However, standing in front of the toaster oven, you need to be more refined if you want to improve your skills. Because of roasting coffee, technical soup is also an art. With machines, anyone can theoretically hear the explosion, but to burn ‘Right’ and ‘Delicious’ are two different things. It would help if you felt more about the expansion of the seeds, the smell, the smoke escaping, and the roasting temperature. To guess the first crack.

Taste development to first ‘Crack’ when roasts

The coffee flavor is the true goal of the roasting process, even if the first crack and second crack are always given the greatest attention. We also need to describe how the Maillard Reaction and the Caramel Reaction were developed for this reason.

Because the carbohydrates, amino acids, organic acids, etc. present in coffee react with one another, both of the aforementioned events take place before the first crack emerges. When the brown color starts to form, the Maillard reaction takes place, producing a variety of flavors in the coffee. The maillard reaction, which is the drying of sugar by heat and the production of CO2 and H2O that results in the initial crack, is followed by the caramel reaction, which produces the taste. Caramel, however if roasting is left on too long, it can also result in a bitter taste.

first-crack
Configure the coffee bean temperature curve and the typical ROR curve around the first crack

Because events don’t always unfold in the same order, it can be challenging to anticipate with precision when these reactions will take place. There are thousands of other reactions occurring concurrently that also depend on temperature and grain shape. However, by doing so, you can comprehend what is happening in the roasting oven and effectively record the initial Crack stage appear.

Why is it important?

If you spend days at sea, what do you want to see? A lighthouse! Yes, the first lighthouse is more important; it tells you where you are, decides the next destination, and how much more it will appear!

First crack test in the roaster

Coffee, too, when in the roaster, coffee beans have to undergo a multitude of chemical transformations, constantly from the green to the charcoal chemistry; the internal reactions of this grain are the basis for physical changes such as discrimination, and loss of mass, Size expansion… And most importantly, the first explosion. This sign – a naïng way tells you that the coffee beans are ripe, and have developed a full taste, so focus on choosing a stop to end the roasting green coffee process.
The next time you stand in front of the roaster, pay attention to the development of fragrance and colour, focusing on the change in size and shape. And always remember that it takes a lot of practice and research to become a good roaster.

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