From altitude and soil to roast profile and brewing method, there are a number of factors that influence the flavour and aroma of coffee.
One of the most important factors to consider for specialty roasters is degassing. Degassing is the process in which the buildup of carbon dioxide in roasted coffee is released over a period of time.
However, while this may seem like a simple process, degassing can have a profound effect on the flavour of coffee by the time it reaches the consumer. To learn more about degassing, and how roasters can use it to their advantage, I spoke with MTPak Coffee ambassador Daniel Horbat.
What Is Degassing?
When coffee is roasted, thermally-driven chemical reactions lead to the formation of gases inside the beans, the majority of which is carbon dioxide (CO2). While the beans lose some CO2 during roasting, a large percentage of them are gradually released over the days and weeks that follow.
This is what’s known as “degassing”. For specialty coffee roasters, degassing is vital: it ensures that the coffee will be fresh, aromatic, and balanced as intended by the time it reaches the consumer.
This is because the release of CO2 during various stages from roasting to consumption is inextricably linked to the characteristics and properties of coffee. According to a study published in Journal of Agricultural and Food Chemistry, CO2 is a major indicator of freshness, plays an important role in shelf life and in packaging, affects extraction when brewed, and may even affect the sensory profile of a coffee.
For example, if freshly roasted coffee is consumed the moment it finishes roasting, the CO2 can cause extraction to be uneven when brewed. This is the result of CO2 bubbles that disrupt the contact between the coffee grounds and the water. On the other hand, if you allow beans to release too much CO2, the coffee’s flavour becomes flat and stale.
Daniel Horbat is the founder of Sumo Coffee Roasters in Dublin. He won the title of World Cup Taster Champion in 2019, before going on to open his own roastery. He tells me that before you brew a coffee, it’s vital to consider how long it has spent degassing.
“I realised something that’s common among homebrewers, especially during Covid-19 lockdowns,” he says. “When they buy fresh coffee, they get excited and want to brew their coffees right away, without even looking at the roast date.”
Daniel says that this is a big mistake because it doesn’t give the coffee time to degas to its “optimal” level of CO2, which brings out its best characteristics and gives it a more balanced flavour profile in the cup.
How Long Does It Take For Coffee To Degas?
In the first 24 hours after roasting, coffee releases around 40% of all absorbed CO2 because of the pressure in the beans. After that, the process slows down, although the time it takes largely depends on whether the coffee is whole bean or ground.
For whole bean coffee, the relatively small surface area of the beans prevents CO2 from being released too quickly, resulting in a slow degassing process. Conversely, when coffee is ground, its surface area increases exponentially, causing CO2 to escape faster.
However, this is by no means the only factor that influences the amount of time coffee takes to degas. The roast profile, variety, and processing all have a bearing on how long it takes to reach the right CO2 levels.
“For a washed coffee, it’s best to wait for around seven or eight days [after roasting],” Daniel says. “In contrast, for natural coffee, because the seed has stayed in the cherry for a longer time, you need to wait longer. I would say approximately two weeks.”
Roast profile is another key factor. With dark roasts, the beans are heated for longer and at higher temperatures, resulting in a more expansive and “open” cell structure. This means the beans lose CO2 and become stale more quickly than they would for a light roast.
To tackle this discrepancy, Daniel tells me that he puts a big label on his coffee stating both the roast date and the recommended number of days to wait before brewing.
“It’s important for consumers to understand what they’re buying and how to get the most from it,” he says.
While there is no universally accepted time to wait for all coffees to degas, specialty coffee roasters should provide customers with a rough estimate of how long they should wait before consuming the coffee. This way, you will ensure your coffee is consumed at its best, consequently increasing your chances of repeat sales.
Roasters can easily include this information on custom labels next to the roast date or alongside brewing instructions on the packaging itself. Our team at MTPak Coffee’s can also include separate tasting cards with additional information on.
Keeping Your Roasted Coffee Fresh
In his book, The Coffee Roaster’s Companion, Scott Rao explains that during the first 12 hours or so after roasting, the internal pressure of coffee beans is high enough to prevent significant amounts of oxygen from entering its structure.
However, after this period, oxidation is more of a risk, meaning that oxygen causes coffee to become stale and lose its volatile and delicate flavour notes.
If a coffee container contains less than 1% oxygen, the freshness and shelf life of coffee can be extended significantly.
However, the problem with an airtight container is that the coffee continues to release CO2 that subsequently cannot escape. This can cause the coffee packaging to rupture, particularly if the coffee is travelling long distances between the roastery and the café or consumer.
Fortunately, there are several options available for specialty coffee roasters which enable the coffee to degas without coming into contact with oxygen.
The most popular option is the inclusion of a degassing valve on coffee bags. A degassing valve is a one-way vent that releases CO2 while preventing oxygen from entering. This maintains freshness and stops the loss of flavour for up to two weeks, making it ideal for roasters offering coffee in small batches.
Typically, degassing valves consist of five pieces, including a cap, an elastic disc, an adhesive layer, a polyethylene plate, and a paper filter. They can be either visible from the outside or hidden within the layers of packaging.
At MTPak Coffee, we offer BPA-free recyclable degassing valves, which can be added to compostable or recyclable packaging, providing consumers with a fully sustainable coffee bag. This can be done during manufacture or further down the line.
For an extended storage time, Daniel says he freezes his coffee beans.
“Let your coffee degas until it reaches its optimal CO2 level,” he says, “then put it in vacuum pack bags, seal it, and freeze it. It’s important to do this just when the coffee is at it’s best.
“When I came to defrost it, I noticed that even after six months the coffee tasted the same.”
The National Coffee Association suggests that if you do choose to freeze your beans, be sure to use a truly airtight container, and remove as much as you need for no more than a week at a time. This is to avoid the build up of condensation on the frozen coffee.
When coffee is consumed too quickly after roasting, the aroma is powerful, yet the flavour is not well-rounded and, more often than not, produces an astringent cup. On the other hand, when coffee passes its “optimal” level of CO2, the flavours become flat and lose their intensity.
For specialty coffee roasters, it’s helpful to provide clear roast and consume-by dates for customers, as well as features which maintain freshness and preserve flavour – such as a degassing valve.
At MTPak Coffee, we provide fully customisable packaging solutions for roasters, in everything from labels to pouch types. To make sure your customers are always brewing a fresh, balanced cup, we provide packaging solutions that maximise freshness and aroma for the consumer.