Coffee FAQ: "How long does coffee last?"
Posted by Rose Park Roasters' Blogging Crew on 5/25/2013
The final word for how long coffee can last is how that coffee tastes after you've brewed it. So, in some sense you know your coffee's bad when it starts tasting bad. Roughly speaking, we notice that high end coffee begins losing its nuanced edge about a week and a half after the roasting date. This deterioration in the complexity and the nuance of high end coffee can be delayed some by storing the coffee in a cool, but not cold, dry place, away from sunlight, and stored as air tight as possible. Oxygen is the primary culprit. Refrigeration is bad because it dries out the coffee in a bigger way than any benefits the cooler temperature adds. Freezing coffee is also almost always a bad thing. The freezing process is so harsh that in most situations it will again break down coffee to a greater degree than it preserves it.
Even in ideal conditions, you will lose the high end flavor notes in roasted coffee at about the three week mark.
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?
I have been vacuum sealing our coffee beans in mason jars. A quart size jar holds a 14 oz bag almost exactly and FoodSaver makes an attachment that fits over the lid of a standard mason jar. As we use the beans we just keep vacuum sealing it. Since the jars are glass, they are impermeable and easy to clean. I'm not sure if it extends the life because our beans don't last us more than a week anyway and I haven't done a side-by-side experiment to see if there is a noticeable difference.
I find that good freshly ground beans in a quality burr grinder makes more of a difference than age of roasted beans. When coffee goes bad, I can definitely tell because it tastes a bit off, but at that point it's been 2-3 months.