How much should I roast at a time.
Under-loading your roaster may result in inconsistant cooking of the bean, (undercooked on the inside) and overloading can result in a woody, smoky flavour due to a slower roast time.
Our recomendation is to roast between 1.5 kg's and 0.75 kg's at a time but this is a guide and will require experimentation. Its all part of the fun discovering what works best for you and what sort of coffee profile you looking for.
So what is degassing?
When coffee is roasted, gases form inside the bean. After roasting, gases (mostly carbon dioxide) start seeping out. When coffee is a few days old and very fresh, a bulk of the carbon dioxide formed leaves your beans. During this time, CO2 escapes so quickly it negatively affects the flavor of your coffee by creating an uneven extraction.
How long does it take for beans to degas?
Degassing varies depending on the type of coffee and roast. It, therefore, can take anywhere from 2 to 12 days until the coffee is ready to brew. Some rules of thumb:
• The first 24 hours is when the bulk (approximately 40%) of CO2 leaves the bean.
• Darker roasts usually degas faster than lighter roasts.
• Longer roasts usually degas faster than faster roasts.
In our experiance, with the Machinist Coffee roaster degasing takes between 2 - 4 days, but this is up to you to experiment with.
Why you shouldn’t pre-grind your beans to speed up degassing!
If you grind your coffee well before brewing, degassing significantly speeds up (but not in a good way). The finer the grind, the larger the gas volume is released – making your coffee stale in a matter of hours. This is because the more you grind, the more cells that store these gases are broken up and released. You’re also speeding up the oxidation process by exposing your coffee to oxygen.
What happens once beans have degassed?
Much like a fine wine, freshly roasted coffee gets better with time…well, to an extent. After the first few days of degassing, oxygen starts to make its way into your beans. This is called oxidation and is the main cause of staleness. A way to prolong the flavor of your coffee is to store it in a container with a one-way valve. This way, CO2 is able to escape, and oxygen won’t as easily find its way in.
To sum up, “fresh” isn’t best if you’re dealing with freshly roasted coffee (mind you, if we’re talking fresh as in roasted recently and degassed, versus months old grocery store coffee – that type of fresh is always best!)