Posted by Rose Park Roasters' Blogging Crew on 5/25/2013
Now the longer, more complex, answer: You can also drink coffee too soon after being roasted. Coffee requires at least one day, and up to three days, for a degassing process to occur. Roasted coffee is full of volatile carbon dioxide gas. Most of it leaves the beans during that first 72 hour period. But that carbon dioxide is not a generally good addition to the coffee's flavor or mouth feel. Espresso, in particular, requires an extended degassing process. For Espresso, the flavors will typically improve over the course of the first week after roasting, and sometimes the improvement will continue for two full weeks after roasting. This occurs for the same reasons that affect brewed coffee, but additionally, if there is too much CO2 in the Espresso then it creates an excess of those coffee oils that foam at the surface of a pulled shot. Basically the volatile CO2 attaches to some of the oils in the Espresso and thereby leave those oils and CO2 bubbles suspended at the surface of the pulled shot. Having an excess of CO2 conglomerated oils can be a detriment to tasting because the oil will embed in the taste buds and repel the more soluble elements of that espresso. Oils are tasty and good, but they are only one part of what makes espresso delicious. Additionally, as coffee ages after being roasted, its different chemical components develop or recess at differing rates. Therefore, letting a coffee age some can be a method of striking a better balance in any particular coffee's flavor profile between aspects such as acidity, sweetness, bitterness, and possibly even mouth feel.
Shelf Life of Green Coffee
Lastly, I want to touch on the shelf life of not-yet-roasted green coffee. Again, the final word is determined by experience. However, typically, if stored correctly, green coffee can be kept 9 months to a year from the time it was harvested without much, if any, deterioration. Green coffee is much more stable than it's roasted counter part. At Rose Park Roasters we typically try to sell through a particularly coffee within 6 to 9 months. Once it hits that 6 month mark after harvesting we keep a close watch on it. The moment deterioration begins to show up- and it starts as a subtle dullness amongst the flavor notes where there used to be poignancy- we shut it down. We sell the best coffees that can be found anywhere and we don't compromise on coffees that have lost their edge.
And Finally, A Question
We're curious what people's experiences have been with the shelf life of coffee. Any stories out there? Opinions on unsealed coffee bags vs. sealing and nitrogen flushing?