Few factors have more of an impact on the freshness of coffee than degassing. Defined as the release of built-up carbon dioxide from roasted beans, degassing is a vital phase that must take place to ensure the coffee is at its “peak” when consumed.
However, unlike the transformations that occur during a roast, degassing is not something that can be readily observed. Therefore, for specialty roasters, it can be difficult to determine at what point their roasted coffee should be packaged for storage or distribution.
While some propose packaging the coffee soon after roasting, others suggest it is better to give the beans time to “breathe”, where they can continue developing their flavours and aromas.
To find out more about the best time to package roasted coffee, I spoke with 2018 German Barista Champion and Head Roaster at Röststätte, Nicole Battefeld.
Read next: Preserving coffee freshness: Degassing valves & resealable zippers
What is degassing?
When coffee is roasted, it undergoes a number of thermally driven chemical reactions as it transforms from raw green beans to a consumable good. During a roast, complex carbohydrates break down into smaller molecules, the beans turn brown, and water vapour escapes.
One of the most notable of these reactions is the buildup of volatile gases inside the beans, which causes their volume to increase by up to 80%. While some of these gases are released during roasting, the rest remain inside the porous structure of the roasted beans and gradually release in the days that follow. This process is known as degassing.
Of all the gases, carbon dioxide (CO2) invariably accounts for the largest percentage, and is linked to a number of coffee’s characteristics. According to the Journal of Agriculture and Food Chemistry, CO2 is an indicator for freshness, plays an important role in shelf life, affects the extraction process, is involved in crema formation, and may affect the sensory profile in the cup.
The rate at which CO2 is released depends on a number of factors, including roast profile and bean density. Generally, in the first 24 hours after a roast, the level of CO2 drops by around 40%, before releasing more slowly. However, this will accelerate upon grinding and extraction.
How do specialty roasters approach degassing?
Due to variation between coffees, there’s no official rulebook when it comes to how roasters should approach degassing. However, it’s generally agreed that the coffee should be allowed a certain amount of time to “breathe” at the roastery before being packaged and distributed.
Nicole Battefeld is Head Roaster at Röststätte in Berlin. In 2018 she was crowned German Barista Champion and the following year she was a finalist in the World Coffee in Good Spirits 2019. She tells me that brewing coffee too soon after roasting tends to skew its characteristics.
“Directly after roasting, coffee doesn’t smell like coffee,” she says. “It smells grainy and a bit like popcorn. This is also reflected in the taste. Fresh out of the roasting tray, coffee tastes grainy, unbalanced, and a little bit weird.”
She explains that roasters must become accustomed to these strange tastes and aromas as they’re required to test the coffee’s potential before it’s sent out. Monitoring how flavours and aromas change over time helps them finesse roast profiles to ensure they produce the best coffee possible.
However, for consumers this isn’t the case. They want to know that when they buy the coffee, it’s ready to be brewed and consumed. If it tastes grainy or unbalanced, it’s likely to put them off choosing that coffee brand again.
“I’d advise everyone to research and monitor their coffee,” Nicole says. “If you think your coffee tastes better when you pack it fresh off the roaster or after three days will depend on your research. Dialling in sheets can help you keep track.
“For customers, always print the roasting date and suggestions for when the coffee is at its peak. At Röststätte, we provide customers with detailed flavour developments for each coffee, including their optimum tasting dates.”
The pros and cons of packaging before degassing
Although it might be tempting to put roasted coffee straight into pouches ready for distribution or storage, specialty roasters need to consider the pros and cons of doing so.
Nicole explains that because the rate of degassing tends to be at its highest immediately after a roast, it can cause a swift buildup of CO2 that has the potential to rupture airtight bags and containers.
She recounts one instance in which she stored freshly roasted coffee in buckets that came with an airtight seal. When she came into the roastery the next day, the buckets had exploded, spilling coffee all over the floor and damaging the ceiling.
As a result, she suggests allowing the coffee 48 hours to degas in open buckets before putting it into bags. This gives it enough time to release a lot of its built-up CO2 and prevent coffee bags from looking bloated when on the shelf.
That being said, Nicole warns that when coffee degases in open containers, degassing isn’t consistent. This can lead to inaccurate aging dates and makes it harder to be precise with a coffee’s flavour notes.
Instead, packaging it immediately after roasting in bags fitted with degassing valves (one-way vents that allow CO2 to escape without letting oxygen enter) ensures it degases in a controlled environment. This helps it age slower and protects its flavour.
The only downside to this is that consumers often get confused about how to recycle their coffee bags when they’re fitted with degassing valves. Most will need to be removed and disposed of separately to ensure the bag is recycled, which is an added inconvenience for consumers.
While the decision to package coffee before or after degassing largely comes down to the roaster’s preference, you can make your life easier by opting for coffee pouches fitted with degassing valves. At MTPak Coffee, we offer a range of sustainable multilayer packaging options, including kraft paper, rice paper, PLA, and LDPE.
Each one can be fitted with a BPA-free recyclable degassing valve either before or after manufacture. Not only does this allow the coffee to release CO2 without letting oxygen in, it also ensures consumers have a fully recyclable coffee bag that can be disposed of without the need to remove the degassing valve.
For information on our sustainable coffee packaging and recyclable degassing valves, contact our team.
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