- Trailblazing roaster George Howell has been freezing both green and roasted coffee since 2001, but the practice became much more widespread in the mid-2010s.
- Many assert that it can prolong the freshness of roasted coffee for up to a year, spurring its popularity among industry professionals and coffee enthusiasts.
- Research from the SCA found that the rate of degassing significantly slows down when freshly roasted coffee samples are stored at -25°C (-13°F).
- The practice, however, is often not as simple as storing a bag of roasted coffee in the freezer. Internet forums are full of questions about how to freeze coffee, giving baristas an opportunity to share best practices.
The practice of freezing both green and roasted coffee took the specialty coffee industry by storm in the mid-to-late 2010s.
First pioneered by George Howell in the early 2000s, the technique gained popularity after the 2017 Re:co Symposium, where George showcased several coffees that had been harvested four years prior. The coffees tasted as fresh as the day they were frozen, transforming our preconceptions about quality and flavour.
Since then, many high-end roasters and cafés have adopted the practice, enabling them to serve what was once impossible: coffees roasted months or years before.
Specialty coffee enthusiasts have also taken up the practice, asking for tips and guidance on internet forums. Techniques can vary; some vacuum seal coffee in bags, while others store samples in test tubes.
There are a few points of contention concerning frozen coffee, including proper storage conditions and when to grind it. As interest in this practice continues to grow, baristas have an opportunity to guide consumers in the right direction.
I spoke to George Howell of George Howell Coffee, Tom Finch of Manchester Coffee Archive, and Ella Turnbull at ST. ALi to learn more.
You may also like our article on whether grinding frozen coffee damages your grinder.
Why freezing revolutionised roasted coffee freshness
Freshness is always a concern for coffee, especially when it’s roasted. Roasted coffee beans are porous, so over time, exposure to heat, light, oxygen, and humidity will degrade quality and flavour.
In the pursuit of coffee excellence, industry professionals look for solutions to preserve freshness and flavour as much as possible. Freezing roasted coffee, a relatively new concept, has emerged as one of the most effective.
“It’s the idea of essentially ‘stopping the clock’ on a coffee’s ageing process, and how this can be utilised to achieve a specific set of benefits,” says Tom, the co-founder of Manchester Coffee Archive, a crowd-sourced collection of frozen, high-quality, and vacuum-sealed coffees.
The science behind it is relatively simple: storing beans at sub-zero temperatures actively prolongs shelf life and extends freshness by decelerating the rate of degassing. Research from the SCA found that this process significantly slows down when freshly roasted coffee samples are stored at -25°C (-13°F).
Although it’s now an increasingly common practice among specialty coffee businesses and enthusiasts, freezing both green and roasted coffee was once a novelty.
George Howell, a pioneering industry figure and founder of George Howell Coffee, spearheaded the trend. He first started to freeze green and roasted coffee over twenty years ago and remains an ardent supporter of the method for preserving coffee’s best qualities.
But the practice garnered more widespread attention at the 2017 Re:co Symposium, when George served coffees which had been harvested years prior.
“We had three different green coffees that were each over three years old,” he tells me. “Before roasting, we had to hold them for a few days so that the temperature was correct.
“People were lining up for these coffees, which were from Kenya, Ethiopia, and Guatemala.”
Freezing is becoming standard practice in specialty coffee
Less than ten years ago, the idea of freezing roasted and green coffee was largely unheard of – or even frowned upon in some cases.
“We used to hear just a few years ago that you shouldn’t freeze roasted coffee, then Kyle Ramage, the 2017 US Barista Champion, proved them wrong,” says George.
During his routine, Kyle used dry ice to freeze his coffee before grinding, asserting that it resulted in a more even and consistent grind size, as well as sweeter flavours.
Scientific research backed this decision. A 2016 study led by Christopher Hendon found that ground coffee particles became smaller and more uniform in size at lower temperatures, with the most significant change occurring between room temperature and -19°C (-2.2°F). Smaller, consistently-sized particles allow for more even, higher levels of extraction, thereby releasing more flavours.
“Freezing coffee was one of those game-changing but, in hindsight, obvious breakthroughs,” says Ella, the head of quality control at Australia’s ST. ALi. “It’s effective, simple, and highly repeatable. I still find it surprising that we weren’t all doing it earlier. A few people experimented, shared their results online, and the practice spread rapidly.”
Today, a growing number of high-end specialty cafés – including ST. ALi, Proud Mary, ONA, Rosslyn, and George Howell – are showcasing the benefits of freezing coffee.
“For businesses, having a ‘freezer stash’ is a practical way to keep numerous top-tier coffees on hand at all times, without having to worry about wastage,” Tom explains. “Many businesses have realised this is an easy way to add something fun to their offerings, which will cater to people looking for more unique coffee experiences.
“This can be an off-menu selection for those in the know, or a reserve menu freely available to view: there’s a lot of scope for creativity.”
Consumers, meanwhile, have an opportunity to try something truly unique: coffees harvested or roasted years prior.
“At our cafes, we have special edition frozen coffees for pour over specifically,” George says. “Right now, we have La Calaca Gesha from El Injerto in Guatemala for a limited time, and we always offer the Kenyan Mamuto as frozen.”
Consumer interest in frozen coffee is rising
As more specialty coffee shops and roasters demonstrate the incredible potential of freezing roasted beans, consumer interest is steadily growing.
“At home, people like freezing coffee because it means you never run out of it; I always have some rested coffee in the freezer ready to brew,” Tom says. “Freezing allows people to buy in bulk and gradually use the coffee as needed, rather than worrying about it going stale on the shelf.”
Numerous online coffee enthusiast forums are full of questions about freezing coffee, particularly roasted beans. But without formalised, universally accepted industry best practices, confusion still persists.
While some posts claim that freezing roasted coffee in its original packaging is a convenient way to store it, industry professionals assert that vacuum sealing is the proven method to preserve freshness for as long as possible.
“Roasted coffee bags have one-way valves,” George highlights. Although the rate of degassing significantly slows down at lower temperatures, it’s still important to minimise any exposure to oxygen.
“Rachel Apple held some of our frozen roasted Geshas for over a year, and they were always vacuum-sealed,” George adds.
Batch size and rate of use will also influence storage conditions.
“Freeze beans in pre-weighed single doses ready for use, so you’re not opening and closing a container every time you want to dip into your stash,” Ella says. “This prevents exposure to oxygen and moisture and preserves beans for longer.”
Glass test tubes are often best suited for single doses, whereas vacuum-sealed containers or plastic bags are more suitable for preserving freshness in larger quantities of roasted coffee.
“Single doses will last a week or two, but if you want to wait a month or longer, you need to vacuum seal,” George explains.
Regardless of the timeframe between freezing and brewing, George, Tom, and Ella all agree on two basic principles: store beans in a well-kept, clean freezer maintained at stable temperatures and always grind from frozen.
“For consistency, dial in the coffee frozen, and then the parameters should stay intact when you next brew the coffee,” Ella shares. “If possible, use a freezer you don’t open regularly to minimise temperature fluctuations.”
“Frozen roasted coffee beans are more brittle than room temperature beans as the moisture and oils within solidify,” she adds. “This will give you a more consistent size and shape of grinds, and with fewer super-fine coffee particles, leading to higher cup clarity and even extraction when brewed.”
“We always grind straight from frozen,” George says. “My understanding has always been the colder the better.”
How baristas and roasters can share best practices
Like any theory or practice in specialty coffee, more formal, scientific research is necessary to better understand freezing roasted and green coffee.
“We need to encourage people to test things themselves and see the results,” Tom says. “There isn’t a huge amount of reliable data to consult when it comes to coffee freezing, and I try not to sound like I know all the answers, even though I have been freezing for a long time now.
“We have a freezing guide on our website that I wrote as a sort of literature review when I first got into the practice,” he adds.
Ultimately, it’s down to coffee shops and roasters to continue investing in the practice, developing a deeper understanding of what conditions help preserve the quality and flavour of frozen coffee for the longest possible time. In turn, baristas – often the closest point of contact with customers – can disseminate the correct information.
“Talk to your customers. The great thing about frozen coffee is that it’s useful and applicable for every customer,” Ella asserts. “Freezing coffee, if done correctly, is immediately practical and useful for most people.”
This is particularly important for home roasters, who are showing increasing interest in freezing green coffee. The quality preservation process, however, begins at farm level.
“When freezing green coffee, the processing and the drying have to be spot on; otherwise, the green coffee will only last a year or so,” George explains. “But when done right, the coffee can last three to four years.
“You need to know as close to the exact harvest date as possible, and vacuum seal the batch size that you’ll roast,” he adds. “As long as the seal lasts, the coffee will stay fresh for a long time.”
There’s still much more to learn about freezing roasted and green coffee. With the practice still popular today, especially among coffee enthusiasts and home roasters, there’s a critical need for further research and controlled experimentation.
Sharing best practices and research-backed guidance will only help this technique proliferate, allowing more people to expand their conceptions of coffee freshness.
Enjoyed this? Then read our article on how you can freeze green coffee.
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