Coffee freshness plays a huge part in brew quality. The taste of your espresso shot, French press, or pour over coffee will change noticeably as the beans age. For this reason, the more you can do to preserve coffee freshness, the better your cup will taste.
USE WITHIN 15 DAYS
A study in the Journal of Agriculture and Food Chemistry Sensory on the aroma compounds of roasted Arabica coffee found over 20% of all aromatic compounds in existence were contained in the aroma of freshly roasted coffee. The make-up of coffee aroma is very complex, consisting of several hundred or more compounds. Of course, we already know that coffee aroma is a very fragile and delicate thing which deteriorates quickly and needs all the storage help that we can give it!
Most would agree that coffee should be consumed as quickly as possible after it is roasted, especially once the original packaging seal has been broken. But this raises the age-old question:
HOW LONG DOES COFFEE STAY FRESH?
Consider coffee the same as any perishable food, because that's exactly what it is! This concept is simple, and yet so often ignored. Just like a loaf of bread or a piece of fruit, coffee's freshness enemies are moisture, heat, and oxygen.
ROASTING CHEMISTRY
During the roasting process, green coffee beans undergo many transformations and chemical changes, and importantly, produce organic gases (mostly CO2) which are trapped within the bean.
After roasting, the beans immediately start to de-gas by giving off carbon dioxide; this acts as a protective barrier against oxidization. As the trapped carbon dioxide gas is released from the bean, damaging oxygen (from the surrounding air) is absorbed in its place. Basically, the oxygen slowly turns the coffee oils rancid. Thus, the staling process begins. De-gassing is most rapid right after roasting and diminishes over time. Roughly 60% of the gas is released after about 7 days.
CAN COFFEE BE TOO FRESH?
The best time to brew coffee after roasting depends on how you plan to brew it.
Logically, one would think the sooner the better. And from a strictly aroma and freshness point of view this is true. In the first few days after roasting, the CO2 released by the beans protects the volatile organic compounds from oxygen in the surrounding atmosphere, so the aroma and freshness will remain close to 100%. But all that de-gassing affects “brew-ability”, if you will. For pour-over, press, and basically any “non-pressurized” hot brewing method, the fresher the better. Nevertheless, it helps to wait a day or two after roasting, as freshly ground coffee will release a lot of gas during the brew process and the resultant frothy bloom can cause problems.
For espresso, one week is the preferred wait time. Again, the issue is the gas stored within the bean. The coffee is so dynamic, with properties changing so quickly, that dialling in the espresso is very challenging for any barista. This is a case of the negatives outweighing the positives. For this reason, most experienced commercial roasters will time their shipments so that customers will receive it after a week, once the beans have stabilized to a degree. Paradoxically, while many of the pleasing-to-the-palate volatile organic compounds will start to degrade within days, some of the objectionable flavours will actually diminish and mellow out as they oxidize over time!
THE BAG MATTERS
It is because of these trapped and escaping gases that the modern (1985) one-way valve oxygen-protecting foil bag was developed. The valve allows the buildup of gas inside to escape without allowing oxygen (air) to enter the bag from outside. Using a one-way valve bag allows the roaster to hot-pack the beans almost immediately after roasting, thus flushing a large portion of oxygenated air out of the bag while the beans de-gas.
Additionally, some roasters flush the bag with inert nitrogen while the bag is filling. If done correctly, this can result in an oxygen volume of less than 2% in the bag. Nitrogen flushing is especially important for the larger roasters who supply coffee nationally or where the bag may sit on a store shelf for several months. Some roasters put a best-before date a whole year forward on their bags which, while rather optimistic (especially for a real coffee connoisseur), makes it easy to figure out when the coffee was packaged and make an informed purchasing choice.
We've found that beans in a valve-locked bag degrade approximately 5-10% in freshness each month.
Beans that are sold in paper, poly-lined burlap, glassine-lined paper, or a high-barrier foil bag without a one-way valve will not stay fresh. Treat them the same as an open bag of beans.
OPENING THE BAG
For all intents and purposes, this is the single most important date for the consumer. The real and rapid staling of coffee begins now. The changes are detectable within a few days and very noticeable within about 10 days, at which point 50–70% of the volatile compounds will be lost or stale. At the 2 week mark most people will no longer relish their morning brew.
For the purists, we recommend storing beans in an airtight canister like the Vacuvin or the Airscape, which reduces exposure to oxygen.
One more important tip: cooler is better. Lower temperature does slow down aging, regardless of whether the bag is sealed or open. Professor Chahan Yeretzian, a PhD chemist whose specialty is coffee said in a recent interview with Sprudge , “If you cool coffee just 10 degrees below room temperature, this “aging” process will be slowed down by a factor of 50%”.
So, if you can keep your coffee (sealed or opened) at say, 10°C instead of 20°C, your coffee will stay fresher longer. However, don't put opened coffee bags in the fridge — humidity and food smells will do more damage than good.
TO FREEZE OR NOT TO FREEZE?
Before we get to the freezer discussion, a general point about coffee storage temperature: To say that the jury is divided on freezing coffee is an understatement. Most in the coffee industry stand firmly by the statement, “Whatever you do, don't freeze your coffee!”. Ask nearly everyone else and they'll tell you the same thing. But try finding an actual study to validate the "don't freeze" position — there are none!
Even the NCA (National Coffee Association USA) provides ambiguous advice:
“While there are different views on whether or not coffee should be frozen or refrigerated.…..If you choose to freeze your coffee, quickly remove as much as you need for no more than a week at a time, and return the rest to the freezer before any condensation forms on the frozen coffee”.
But nothing speaks louder than experience. Try keeping a bag of valve-locked coffee beans in the freezer and another in the kitchen cupboard, and compare them at the three- and six-month marks. A simple experiment, but an effective one.
Recommendations for freezing coffee to keep it fresh date back a lot further than many might suspect. The Signet Book of Coffee and Tea, originally published in 1976 at the beginning of the specialty coffee movement, recommended freezing coffee for freshness. “Since coffee beans retain their flavour up to three or four months if frozen — particularly if the temperature is below 0F — you can dispense with weekly trips (to buy coffee) by simply laying in a number of pounds of particularly fine coffee you come across”. The authors emphasize the importance of moisture-proof storage.
Then there's this from award winning author Kenneth Davids (also from 1976): “Freezing, however, is an excellent way to preserve whole-bean coffee if you do not intend to drink it within a week.” And in 1991, Nich Jurich wrote in Espresso: from Bean to Cup, “The only time you should freeze coffee is when you plan to keep it longer than two weeks”.
More recently, several well-respected coffee experts present strong empirical evidence in favour of freezing coffee that won't be consumed within a week or two. Ken Fox and Jim Shulman, two long-time respected coffee stalwarts of home-barista.com completed two tests several years ago: in the first, they found no discernable difference between fresh roasted and coffee frozen for 8 weeks; in the second (which was more detailed) they tested the coffee after 4 months and concluded, “Freezing remains a viable method for the preservation of coffee roasted for espresso, for a period of at least 4 months.…..It seems unlikely that freezing and defrosting has no effect at all on roasted coffee; but I think, given these results, it is impossible to claim that the effect of freezing is larger or more harmful than any of the other things we do with fresh roasted coffee in the first week of its life.”
Scott Rao, who is the author of four definitive coffee and espresso books (and who is widely considered to be one of the world's most influential coffee thinkers), also believes freezing is beneficial. In The Coffee Roaster's Companion, he writes:
“Although it still has its skeptics, freezing coffee has proven itself to be very effective for long-term coffee storage. Freezing decreases oxidation rates by more than 90% and slows the movement of volatiles.”
In Espresso: Ultimate Coffee Kenneth Davids, author of three coffee and espresso books and of coffeereview.com writes:
“If, however, you shop for coffee less frequently than the righteous coffee lover truly ought to, and if you keep your whole-bean coffee around for more than a week before you consume it, place it in carefully sealed freezer bags in the deepest recesses of a good freezer as soon as you get it home.”
At least two prominent commercial roasters are on record recommending that consumers freeze coffee for longer term storage. Kaladi Coffee Roasters of Anchorage, AK freeze all their coffee beans not sold or consumed within 18 hours of roasting! It says on their website:
“To preserve the superior properties our roaster creates, we freeze all coffee not used within 18 hours of roasting. This process ensures our coffee is absolutely "roaster fresh" when you purchase it. Freezing coffee in an airtight container is the only scientifically proven method for extending the life of roasted coffee beyond a few days.”
Gaviña, the producers of California's Don Francisco Coffee, asked their in-house Q-graders (highest rank of coffee taster, similar to a wine sommelier) to conduct a three-month test, after which they concluded the optimum taste comes from coffee beans that have been frozen for up to six weeks.
Finally, Karen Paterson, owner of Hula Daddy Kona Coffee has an excellent summary on the whole freezing debate:
“Brewing coffee beans between 3 and 10 days after roasting is best. If coffee cannot be consumed before 10 days after roasting then freezing the coffee is a good alternative. The enemies of coffee freshness are heat, water and oxygen. Properly frozen coffee beans defeat all three.”
SO THERE YOU HAVE IT.
For the freshest coffee, follow Reg's rules:
- Freeze coffee as soon as you can after it is roasted, if you don't plan to consume within 10-14 days.
- Preferably only freeze un-opened valve-locked laminate bags from the roaster. Tape over the valve; when frozen, the plastic one-way valve can turn into a two-way valve letting moisture in.
- If you wish to freeze smaller portions of coffee use Ziplock freezer bags (not regular style), or if you have a vacuum sealer use it.
- Let the frozen bag warm up to room temperature overnight before opening up, to avoid moisture in the form of condensation damage the beans. Anyone who wears glasses in below freezing weather who steps into a warm room knows exactly what I mean. And never re-freeze.