Freezing coffee to preserve freshness is a method that continues to divide opinion among specialty coffee roasters.
Those who advise against its use claim that freezing the beans affects a whole series of qualities, from flavor to moisture content, while its proponents say it is a very effective method of long-term storage, as it helps to slow the release of CO₂ and to avoid oxidation.
Read on to learn the reasons for freezing coffee and how this can preserve the freshness of the beans.
Why should roasted coffee be frozen?
Heat, light, oxygen, and humidity are the worst enemies of coffee. They break the organic cellular structures of the grains, alter humidity levels and promote bacterial growth. This causes the coffee to lose its flavor and freshness and drastically decreases its shelf life.
However, keeping your coffee out of the elements can be difficult and expensive, especially if you plan to store it for a long period of time.
George Howell is the founder of George Howell Coffee, based in Boston. He began freezing coffee almost twenty years ago and remains a fervent advocate of this method of preserving the best qualities of coffee.
“I have found that just one day after opening a bag of coffee, exposing it to oxygen, it loses much of its dimensionality,” he explains. “You can’t just put it in a container and take the oxygen out of it like wine; the carbon dioxide comes out of the fresh coffee, eliminating any vacuum seals with which you started ”.
“Freezing the coffee, on the other hand, stops all interactions immediately.”
One of the reasons why freezing coffee is so effective in preserving it is that it prevents oxygen from penetrating the cell structure by slowing the rate of degassing.
When coffee beans are roasted, they absorb a large amount of carbon dioxide (CO2), which is then released in the days and weeks that follow. However, if the CO2 content falls below the “optimal” level, the coffee will lose flavor and become flat.
A group of researchers who analyzed the impact of freezing coffee found that storing beans in sub-zero temperatures actively prolong shelf life, extending freshness from three months to a year.
They studied freshly roasted coffee samples stored at 35 ° C and -25 ° C and concluded that degassing rates had decreased significantly for coffee stored at -25 ° C.
“[Freezing coffee] can actually preserve its flavor, extend its expiration date, improve sustainability, and make a huge difference to the industry as a whole,” says Hugh Kelly, member of the R&D team at ONA Coffee. Melbourne.
“It allows us to completely stop the cellular activity of the coffee particles. This means that we can capture or block the window when the coffee has the maximum flavor, freeze it at that point and stop the old problem of the coffee going stale, ”he adds.
But not everyone shares the belief that freezing coffee is a good way to preserve it.
The National Coffee Association of the United States (NCA) states that since beans are hygroscopic (they absorb moisture from the air), consumers should consider how humidity from the freezer can affect their coffee. If coffee is repeatedly stored and removed from the freezer, condensation may form, rendering the coffee tasteless.
If you still decide to freeze your coffee, the NCA recommends scooping out the amount you need quickly for no more than a week at a time and returning the rest to the freezer before condensation forms.
Grind the beans frozen or at room temperature?
A common point of contention regarding frozen coffee is when to grind it.
Some suggest that the colder the beans are when ground, the better the cup will taste. This is because when the mill strawberries are heated, the number of fines is reduced and uniformity is lost.
A smaller total surface area usually results in a coffee that tastes sour, uneven, and relatively little extracted when brewed. Therefore, it is believed that since the coffee beans will be cold at the time of grinding, the temperature of the strawberries will be kept low, therefore, the extraction will be more uniform and as a result, the final cup will taste better.
According to a Daily Coffee News article, Oregon-based Proud Mary Coffee Roasters freezes all of its green and roasted coffee after experiencing positive results from cold-grinding coffee beans.
“With one of our high-end featured Brazilian coffees, we really got a lot more clarity, character, and flavor from the frozen sample than [from that] at room temperature,” says Nolan Hirte, founder of the company.
However, others refrain from grinding frozen coffee and insist that it is best to wait for it to thaw at room temperature before grinding it.
An investigation by Compound Coffee Company found that its washed Ethiopian Kochere coffee exhibited the highest extraction rates when frozen beans were allowed to come to room temperature before grinding.
The extraction rate is the amount, by weight or percentage, of dry coffee dissolved in the water with which the coffee is prepared. The extraction rate calculated for ground coffee at room temperature was 22.56%, compared to 22.45% for frozen coffee.
It was observed that, although both coffees were floral, sweet, and well rounded, the coffee that was allowed to warm to room temperature before grinding did not produce bitterness, while the frozen ground coffee had a slightly bitter finish.
Best Practices for Freezing Coffee
If you decide to freeze your coffee, there are a few factors to consider before doing so.
To keep coffee at its freshest, the beans must be frozen before they reach their maximum flavor. This varies based on several factors, from roast profile to bean density.
However, it is usually between nine and ten days after your roast date. Roasters can do this to ensure that when beans are removed from the freezer and packaged for distribution, they arrive at the coffee shop or home brewer in maximum freshness.
Also, it is recommended to divide large amounts of coffee into smaller portions before freezing. This avoids exposing the beans to oxygen, which will cause them to go rancid. Coffee roasting expert Scott Rao suggests putting a single serving in an airtight bag and freezing it, rather than large amounts at once.
Freezing coffee is considered by many to be a very effective way of preserving freshness, maintaining flavor, and preventing it from going rancid. It enables specialty coffee roasters to keep their coffee at its peak of flavor and ensure that when it reaches the consumer, it will always have a pleasant experience.
You can also choose to add a host of innovative features that allow homebrewers to keep their coffee fresh once they bring it home, from degassing valves to resealable closures.