Keeping it Fresh! How long does coffee stay 'fresh' for?

Friday, 23 September, 2022

One of the most asked about topics in the coffee world centres around ‘freshness’.

How quickly should I use my coffee after I buy it? When does coffee stop being ‘fresh’? What can I do to keep my coffee fresh?

The accepted wisdom on what constitutes fresh coffee has been updated in recent years. As the the people behind coffee delve deeper and deeper into the science, they have been experimenting with this idea. Delicious experimenting. Brewing coffees at different days post roast to see what flavour notes come out at different stages of de-gassing.

Ok, so let’s unpack that term a bit. De-gassing.

When coffee comes out the roaster (can’t get fresher than that!), gases form inside the bean. Hanna McPhee of Fellow Products, a company that has designed their coffee products using as much science as possible, explains.

“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. This degassing process is the reason roasters start selling their coffee a few days to a week after the roast date.”

“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.”

So then the experimenting comes in! Companies like Toby’s Estate, based in Australia, work really hard to provide both their wholesale customers and consumers with the best possible possible chance of getting the peak flavour from a coffee by offering brewing cards that include different brewing ratios the further from roast date you get.

Roasters understand that time is a big factor especially when it comes to the retail space. One of the ways in which roasters combat this is by nitrogen flushing bags filled with coffee before they are sealed.

Nitrogen is a gas that makes up about 78% of the air that we breathe, and the remaining 21% of air is oxygen. Oxygen is the enemy of freshness. Oxidation breaks down any food product, staling it rapidly, but nitrogen has the opposite effect. It helps preserve freshness. Coffee bags are sealed so that no air can seep into the coffee, but there is a one-way oxygen release valve on the bag which allows oxygen to escape. That’s the valve you may have used to smell coffee on a shelf by squeezing it! Nitrogen is heavier than oxygen, so when filling a bag with nitrogen, it will naturally push the oxygen up and out, where the bag is then quickly sealed, removing all the oxygen within the bag.  The equipment necessary for nitrogen flushing is quite pricy, but a worthy investment especially for coffees sold on supermarket shelves.

Sealed nitrogen-flushed coffee can stay ‘fresh’ for up to six months after the “roasted on” date printed on the bag. However, once the bag is opened, it’s recommended that the coffee is used immediately over the next 7-10 days.

Most coffee professionals can agree that storing your coffee after it has been opened should be in an airtight container of some kind to prevent further degradation.

Donovan McLagan, SCA Roasting Trainer, 4-time SA Cup Tasters Champion and owner of Cabal Coffee, generally recommends that people use their coffee 1 month from roast date or latest 60 days after.

“I like to ideally be brewing with coffee in the 10-15 day post-roast region. I have begun to learn that there is a bit of flexibility on that and it can change depending on the coffee and its density.”

“Density is determined by the bean itself as well as how the coffee is roasted.  it affects how the fibres of the coffee are fractured in the roast process and that can speed up or slow down the degassing period. Darker roasts usually degas faster than lighter roasts. Longer roasts usually degas faster than faster roasts. The first 24 hours is when a bulk (approximately 40%) of CO2 leaves the bean and after de-gassing oxidisation starts.”

A huge part of a roasters job is to cup coffee. Generally in this practice the coffees are very close to roast date. McLagan explains why it is important to taste coffee at different stages after the roast

“Understanding on how coffee changes over time helps to mitigate missing flavour notes and when you’re evaluating for quality. I always suggest cupping your coffee for up to 10 days post roast to get a good understanding of how it changes over time.”

McLagan has started doing some research into the results of the A Shot in the Dark 2021 roasting competition around how long each coffee was rested for and collating that with the colour/roast level. The competitors are given the date of cupping ahead so they can submit their coffee to be tasted on the day they think it tasted best.

“There was some very interesting info that came out of the cuppings this year that I think is worth having a look at and warrants some further research. What has become evident from this data we have collected is that end colour and roast date make a difference even if it’s a small one. I would like to have seen if the Top 5 would have changed if I we had cupped a day or two later or two days earlier.” 

It obviously gets very technical. There is also the question of freshness of the green beans before they are roasted. Most roasters are aiming to have the most recent crop of coffee from the producers that haven’t been stored for too long. There are always going to be exceptions that challenge the rule. This year in the World Barista Championships, the representative from Ireland, Wojciech Tysler, presented an ‘old crop’ coffee, harvested in 2019 and made it all the way to the Finals. 

The next idea in freshness is the concept of freezing roasted coffee. Long demonised as unacceptable, mostly because of moisture contamination and freezer burn. But, stored correctly, it has now become quite the trend to preserve coffee. 

“I recently enjoyed a coffee from my travels to Brazil for the Cup Tasters Championship, which at the time of tasting would’ve been about 2 years old!”

What does correct storage mean? Vacuum sealed bags, as you bought it from your roaster if it is vacuum sealed. Pop the whole bag in the freezer and thaw it out when you want to use. Some cafes have whole freezers dedicated to airtight test tube containers of beans measured in grams ready to use for service. You can grind beans straight from the freezer, but the effects of that on flavour is a whole other article!

So next time you buy a bag of beans and check out that roast date, you have few options and maybe a few questions to ask of your roaster. Ask your roaster on how many days you should wait until brewing. Hot out the roaster “fresh” may not be best for brewing immediately. There’s a spectrum and it is so much fun to find out where the sweet spot is post-roast. 

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