"Kraft paper bags are terrible at retaining the quality of coffee. If you do purchase coffee in a kraft bag, transfer the beans to a high barrier container and keep in a cool, dark spot. Warm or moist environments will accelerate the loss of volatile compounds and dramatically shorten the shelf life. Freeze your coffee only in high-barrier containers, and never refrigerate."
Should you freeze your coffee? How long will it stay fresh?
Luckily, lots of research has been done on this topic, and we have a few opinions of our own based on experience working with coffee daily. All coffee, no matter how it is stored, will go stale in taste eventually. While this coffee would not be unsafe to consume, it will have lost its aromatic qualities and have an oxidized taste and smell with a thin, lifeless cup character. How long it takes for coffee to become stale depends on its environment.
There are 3 primary factors that cause coffee to go stale:
Oxygen. This is the biggest one. And modern coffee packaging has largely dealt with removing this inside the packaging. Most specialty coffee sold these days comes in packaging with a one way valve installed. Coffee emits carbon dioxide for around a week after roasting and the valve is there to allow the gas out without allowing oxygen in. Sometimes this type of packaging is flushed with nitrogen gas to remove residual oxygen.
Moisture. In an unprotected environment, such as an opened bag or a bin, this could be a concern. Again, modern packaging effectively minimizes this as a source of staling.
Heat. Generally the cooler the temperature the slower the staling process will occur. Freezing temperatures likely results in the slowest staling possible. More on freezing later.
Most coffees packaged in an unopened, high-barrier bag with a one way valve will retain much of their quality for at least 3-4 weeks. Those that have been flushed with nitrogen, a little longer. The caveat here is we’re referring to the quality of the coffee the first time the bag is opened. Once we break the seal on the bag, we expose the coffee to oxygen and perhaps moisture.
So a better question to ask than, “How long will my coffee stay fresh?” would be, How long will my coffee stay fresh after I open the bag?
With coffees that were roasted within the past week, a few days to a week may pass before noticeable degradation of quality occurs. For coffees that are several weeks or months old, they may taste fresh immediately after opening but will become stale tasting rapidly afterwards. Storing coffees in an airtight container after they have been opened helps. Canisters that can push or vacuum the air out upon closing work even better.
Should I freeze my coffee?
If you will not be consuming a coffee you have purchased within a short amount of time, freezing can be a great way to help preserve its quality, provided it is done carefully. Paper or thin plastic packaging will still allow oxygen to stale the coffee, even when frozen. A coffee in its original unopened one-way valve packaging, however, will fare far better. If you’re planning to freeze coffee, it would be wise to consume it quickly once removing from the freezer, and thaw only what you expect to consume within a week.
PRO TIP: Kraft paper bags are terrible at retaining the quality of coffee. If you do purchase coffee in a kraft bag, transfer the beans to a high barrier container and keep in a cool, dark spot. Warm or moist environments will accelerate the loss of volatile compounds and dramatically shorten the shelf life. Freeze your coffee only in high-barrier containers, and never refrigerate.
Interested to learn more about coffee staling? The Specialty Coffee Association of America has an excellent summary of work on this topic here: What is the Shelf Life of Roasted Coffee