Freezing coffee to preserve freshness is an approach that continues to divide opinion among specialty roasters.
Those who discourage its use claim that freezing affects a range of qualities, from flavour to moisture content, while advocates say that it’s a highly effective method for long-term storage, helping to slow down the release of CO2, and prevent oxidation.
Read on to find out about the reasons behind freezing coffee, and how it can preserve the freshness of your coffee beans.
Why Should We Freeze Roasted Coffee?
Heat, light, oxygen, and humidity are coffee’s worst enemies. They break up the organic cell structures of the beans, alter moisture levels, and encourage bacterial growth. This causes coffee to lose its flavour and freshness, and dramatically decreases its shelf life.
However, keeping coffee away from the elements can be difficult and expensive, particularly if you plan to store it for a long period of time.
George Howell is the founder of Boston-based George Howell Coffee. He first started freezing coffee nearly twenty years ago, and remains an ardent supporter of the method for preserving coffee’s best qualities.
“I’ve found that just one day after I open a bag of coffee, thereby exposing it to oxygen, it has lost much of its dimensionality,” he explains. “You cannot simply put it in a container and remove the oxygen as if it were a wine; carbon dioxide pours out of fresh coffee, eliminating any sealed vacuum you may have started with.
“Freezing coffee, on the other hand, stops all the transactions cold.”
One of the reasons freezing is so effective at preserving coffee is that it prevents oxygen from permeating the cell structure by slowing down the rate of degassing.
When coffee is roasted, the beans absorb high levels of carbon dioxide (CO2), which is released in the days and weeks that follow. However, if CO2 content falls below the “optimal” level, it can cause the coffee to lose its flavour and become flat.
A group of researchers analysing the impact of freezing coffee found that storing beans at sub-zero temperatures actively prolongs shelf life, and extends freshness from three months to a year.
They studied freshly roasted coffee samples stored at 35°C and -25°C, and concluded that the rates of degassing had significantly slowed down for the coffee stored at -25°C.
“[Freezing coffee] can actually preserve its flavour, extend its expiration date, improve sustainability, and make a huge difference to the industry as a whole,” says Hugh Kelly, a member of the R&D team for ONA Coffee in Melbourne.
“It allows us to stop the cellular activity in coffee particles completely. This means that we can capture or lock in the peak flavour window of the coffee, freeze it at that point, and stop the age-old problem of coffee going stale,” he adds.
But not all share the belief that freezing coffee is a good way of storing coffee.
The National Coffee Association (NCA) says that because beans are hygroscopic – they absorb moisture from the air – consumers need to consider how moisture from the freezer might affect their coffee. By repeatedly taking your coffee in and out of the freezer, it can lead to condensation which will leave your coffee flavourless.
If you do still decide to freeze your coffee, the NCA recommends quickly removing as much as you need for no more than a week at a time, and returning the rest to the freezer before any condensation forms.
Grinding From Frozen Or Room Temperature?
A common point of contention concerning frozen coffee is when to grind it.
Some suggest that the colder the beans are when ground, the better the flavour of the cup. This is because when grinding burrs become hot, the number of fines is reduced and uniformity is lost.
A lower total surface area often results in coffee with a sour, uneven, and relatively unextracted taste when brewed. Therefore, it’s believed that because grinding cold coffee beans keeps the temperature of the burrs cool, uniformity will be increased, extraction will be more even, and the final cup will have a better flavour as a result.
According to an article by Daily Coffee News, Proud Mary Coffee Roasters in Oregon freeze all their green and roasted coffee after experiencing positive results from grinding cold coffee beans.
“With one of our high-end Brazilian lights, we actually got much more clarity, character, and flavour from the frozen sample than we did at room temperature,” says Nolan Hirte, the company’s founder.
However, others refrain from grinding frozen coffee, and insist it is better to wait until it has thawed to room temperature before being ground.
Research by Compound Coffee Company found that their washed Ethiopian Kochere coffee had the highest extraction rates when the frozen beans were allowed to reach room temperature before grinding.
Extraction rate is how much – either by weight or percentage – of dry coffee has been dissolved in the water with which you are brewing your coffee. The extraction rate calculated for the coffee ground at room temperature was 22.56% compared to 22.45% for frozen.
They observed that although both coffees were floral, sweet and well-rounded, the coffee left to warm to room temperature before grinding produced no bitterness, while the ground frozen coffee was slightly bitter in the finish.
Best Practices For Freezing Coffee
If you decide to freeze your coffee, there are a few different factors to consider beforehand.
To keep coffee at its freshest, beans should be frozen before they reach their peak flavour. This varies depending on a range of factors, from the roast profile to the density of the beans.
However, it’s usually between nine and ten days after its roast date. Roasters may do this to make sure that when they remove the beans from the freezer and package them up to distribute, they will arrive at the café or homebrewer at peak freshness.
Dividing large quantities of coffee into smaller portions before freezing is also recommended. This is to avoid exposing the beans to oxygen, which will cause the beans to go stale. Coffee roasting expert Scott Rao suggests putting as little as a single serving into an airtight bag and freezing it, rather than great quantities at a time.
At MTPak Coffee, we supply airtight coffee pouches in a range of different sizes and materials. You can customise your pouches to allow customers to freeze their coffee without having to transfer it into a different container.
Freezing coffee is considered by many to be a highly effective way of preserving freshness, maintaining flavour, and preventing it from going stale. It allows specialty coffee roasters to capture their coffee at its peak flavour, and ensure that when it arrives at the consumer they will have a consistently enjoyable experience.
At MTPak Coffee, we’re focused on preserving the fresh qualities of coffee right up until its consumption. We offer a range of sustainable packaging solutions that will protect your coffee, maximise freshness, and ensure the best flavour possible. With our packaging solutions, consumers can freeze their coffee in small batches to ensure it is always enjoyed at its best.
You can also choose to add a range of innovative features to allow homebrewers to keep their coffee fresh once they bring it home, from degassing valves to resealable zippers.