Coffee is not just an ordinary beverage and it has also a lot of science behind it especially the brewed coffee. Every step has a great impact on the taste notes of the beans, it’s not just the cherry after all. The storage of the beans, the roasting, and even degassing. The good thing is Philippine coffee is currently on the rise with a variety of single origins. You can also check out Philippine coffee near me on the net for more information.
While the coffee beans are being roasted, certain heat chemical reactions lead to the formation of gasses on which the large fraction is carbon dioxide (CO2). Part of CO2 is released during roasting while part is retained inside the porous structure of the roasted beans and is steadily released during storage or more on during grinding and extraction. This release of CO2 while the coffee undergoes different phases from roasting to drinking is linked to many important properties and characteristics of coffee. This is also the reason why some coffee containers get ballooned up especially when it has no one-way air valve.
CO2 is an indication of the freshness of the beans and impacts the extraction process which involves the formation of crema and affected the sensory profile in the cup. It is a much undiscussed and little examined molecule in coffee and for this topic, we will talk about CO2 and degassing.
In the past, the total amount of gas or CO2 and degassing rates from roasted whole beans and ground coffee have been measured using 3 different analytical approaches:
The pressure increase was measured in a closed container during the storage of roasted beans and related to the number of released gases.
Monitoring the increasing CO2 concentration in a closed container with a large headspace volume using spectroscopy.
An analysis of degassing of whole roasted Arabica coffee was performed for 3 roasting degrees complete with three different roasting speeds each. They were grouped either for fixed roasting speed or for the fixed roast degree. The profile shows that the roast degree has a stronger impact than roast speed on the total amount and dynamics of degassing of whole roasted beans.
Research shows that for a medium and dark roast with a faster roast speed the degassing is faster while slower than a slow roast. As for the light roast, there was no such increase. The increase of the degassing rate from light to dark roast degree is consistent throughout the data. But well, the porosity of the beans has an impact on the degassing behavior - the darker roasted the beans are, the more porous they are, and the faster the roast, the more porous the roasted beans too. During longer and darker roasts, a higher total amount of gas is produced. This makes sense as to why we recommend that our Mt. Banahaw, Lipa, and other medium dark beans should be degassed for more than a week. We even tested our Arabica up to 4 months of degassing and the result was terrific - the crema is there, the sweetness is there too. Though the aroma was lessened, the taste notes are there. Some of the beans also hit their sweet spots 1 or 2 months after degassing.
On the other hand, the duration of degassing for the roast and ground coffee was shorter than the whole beans and the released amount was smaller. Up to 75% of the trapped gas was released during and immediately after grinding compared to the amount of degassing from whole beans which are freshly roasted. Here’s what makes it interesting, the strong difference is degassing kinetics is believed to be related to the destruction of the pore structure of the beans during grinding when larger macropores are destroyed during grinding and trapped CO2 is released at a high rate.
There is no fixed number of days that pertain to degassing your coffee beans but knowing its roast profile and the other details help you decide when to brew it. Furthermore, it is very helpful to purchase beans as whole beans rather than ground beans.