While most know that coffee loses some of its taste over time due to degradation and oxidation of volatile compounds, the opposite is often true as well: using freshly roasted coffee beans may also compromise the taste of a cup of coffee.

Roasted coffee beans contain a large amount of carbon dioxide – according to Clarke and Macrae (1985), 87% of gases released from roasted coffee is carbon dioxide! In the brewing process, carbon dioxide released during extraction can create bubbles in the brew bed, which might result in an uneven extraction of coffee. To ensure that our coffees are well extracted, brewing coffee beans after allowing it to rest for the right amount of time is paramount.

In fact, here at Homeground Coffee Roasters, we find that cups of coffee that are brewed with freshly roasted coffee beans often have a slightly veiled finish and dull sweetness, possibly as a result of the uneven extraction in the brew bed. Degassing, or the resting of coffee beans, is an important step to ensure greater clarity and development of coffee flavors.

From our experience, many of our coffees seem to really come into their own about 2-3 weeks after they have been roasted. Hence, we often recommend resting our retail coffee beans for 14 days from the roast date before brewing.

In the process of coming up with the recommended number of days, we conducted a simple experiment where we cupped the Caballero Tanairi and Caballero JR #2 from our October Green Series coffee, roasted over the course of a few dates in the past month.

These coffees were roasted using virtually the same roast profile, and packed and stored in our retail coffee bags to fully emulate a customer’s experience with our coffee beans. Additionally, these coffees were chosen as they represent the two general groups of coffee processes, with the natural processed Caballero Tanairi and washed processed Caballero JR #2.

We cupped five samples of each coffee, roasted a week apart from the previous, noting the changes in taste and mouthfeel each time:

Our notes from the cupping show that the flavour profile and clarity of the coffee improves significantly 15 days after the roast date, and continues to improve towards the third and fourth weeks after roasting.

Home brewers who regularly brew coffee often take an estimate of between 1 to 3 weeks to finish a bag of beans. Working backwards from this estimation, opening the bag 14 days after roasting is an ideal starting point to be able to enjoy the progression of the coffee beans as they develop with time.

With resting coffees in mind, there becomes a need to plan for the coffees in our stash – we have to start looking for a new bag of coffee before what we have runs out. Sometimes, this planning breaks down, and we find ourselves low on well-rested beans at home. What do we do then?

Drinking only rested coffee is by no means an absolute rule. Every coffee is roasted differently, and the practice of resting coffee may not apply to every single bag of coffee beans out there. Our coffees can still be brewed even if they are fresh off the shelf – it would in fact be interesting to replicate our cupping experiment at home for yourself, and experience the development in flavour profile as your coffee beans degas over a period of time!

Alternatively, for those who still prefer brewing coffees that are slightly more well rested, there are also certain ways to try to speed up the degassing of a bag of coffee, such as grinding a dose of coffee in advance and leaving it on the countertop, as well as vigorously shaking the coffee grounds. Brew parameters such as agitation, and time and volume used for blooming, can also be adjusted to account for a fresher batch of coffee beans.

It is a constant battle to be able to brew coffee in that golden spot between coffee beans that are too fresh and still in the midst of degassing, and coffee beans that are getting old and losing flavors to oxidation and degradation.

Unlike with older coffee beans, where the process of losing its flavors is a gradual decline, the leap in improvement of the taste of a fresh bag of coffee beans upon its initial degassing in about 2 weeks is a rather predictable outcome. In most cases, it is safer to err on the side of caution, and opening a bag of coffee beans when it is fresh, and to take our time to slowly get through the lot.

However, there have also been many times that we have seen the flavours continue developing even after 3-4 weeks, giving us a fantastic brew that peaks well after one month past the roast date!

Each lot of coffee beans is different, and each brew that we take with the same coffee beans is also going to be slightly different. From the experience of cupping our coffees, a bag of coffee beans should be rested for at least 14 days from its roast date. While it is ideal, it is not a hard and fast rule – the best principle of thought is to enjoy the coffee as the taste profile develops and changes as time elapses.