We’ve mentioned this before, our coffee performs best when thoroughly rested. For both espresso and filter brewing they peak after 30 days. In the case of filter we are happy to brew them after 14 days but after a month is ideal. The experience will be far superior; better flavour clarity, more integrated acidity and less bitterness. They simply open up, tasting more transparent and structured. The idea of using freshly roasted coffee is more or less dead to us. For well over a year now our espresso grinders have been filled with coffee that is a minimum of one month old. Plus most feedback we hear from our clients is how they discover better results with well rested versions of a coffee.
Here’s some scientific theory. When roasting we see the formation of gases within porous structure of a coffee bean, with the largest amount being carbon dioxide. Degassing is the term used to describe the release of carbon dioxide and other gases from roasted coffee. It will happen steadily throughout storage and rapidly once the bag is open or upon grinding and brewing. CO2 amongst other things contributes to crema formation, effects the extraction process and can hinder or obscure the flavour and clarity in the final cup. The research article ‘Time-Resolved Gravimetric Method To Assess Degassing of Roasted Coffee’is a good reference. It takes an accurate, quantitative, and a time-resolved approach to measure the degassing rate of roasted coffee. This test was achieved by measuring the weight loss of a container filled with coffee. Tests were conducted with nine samples, three of each a light, medium or dark roast degree and with varying roast speeds (roast air temperatures).
In conclusion roast degree has a stronger impact than roast speed on the total amount and dynamics of degassing. That light roasted coffee beans are still degassing 1 month after roasting and are slower. Medium and dark roast degrees, the degassing is faster from faster roasts than from the slower roasts, whereas the results from the light roasts show no such increase. The cause of this degassing rate behaviour is generally down to the difference in porosity of the light, medium and dark beans. Basically the darker the roast the more frail and surface holes for carbon dioxide to escape more quickly. We are aware that our continuous suggestion to use longer rested or thoroughly degassed coffee poses an added level of complexity from a planning perceptive. However for the sake of a modern coffee experience it is essential we don't rest on our laurels but on our coffee instead.
- Brightest Regards, Dane Oliver