We have been utilising freezer storage for a little while now in both our cafes and roastery. In the cafes, it means individually dosing roasted coffee ready to be picked out of the freezer and ground and brewed to order. For the roastery, it means freezing green coffee to prolong its quality and then removing the green coffee to roast it when the time comes.
Freezing coffee has become a more and more utilised tool in specialty coffee. Obviously freezing food and drink is a long established approach, however it was not overly present in specialty coffee until the mid 2010s. George Howell based in Boston, US has long been a pioneer in coffee and started freezing green coffee as a way to preserve quality over time. Famously, this was powerfully displayed in a barista competition when one of George’s Kenyan coffees was used with the older harvest displaying better cup quality than the new harvest. This was powerful, as we generally work with coffee as a seasonal fresh crop, expecting quality to drop off relatively quickly.
More and more roasting companies have started utilising frozen green storage, especially for really expensive smaller lots. It means you can run a “cellar” of frozen green coffee that can be utilised as a menu to be selected from over time. We have introduced a freezer menu on our wholesale website that allows our partners to select from frozen green coffee stock to be roasted to order.
The trend of freezing roasted coffee and then grinding it frozen is a little newer. In 2016, we were involved in some research that became an academic paper called “The effect of bean origin and temperature on grinding roasted coffee”. You can read the paper here https://www.nature.com/articles/srep24483. For this paper we created different temperature environments for a wide range of coffees to see if the temperature changes to the beans altered grind distribution. The paper was based on particle distribution, and showed a shift in particle distribution as coffee got colder. Essentially showing that the coffee became more brittle as it got colder. It has become increasingly apparent that there is a lot more going on in grinding coffee than just particle size distribution.
The freezing of coffee started to show up in barista competitions and high end shops as well as in peoples homes around the world. I often prefer coffee that is ground frozen. I believe this is because most grinders damage coffee and that the freezing helps mitigate this. It has thus become common for freezing roasted coffee to be used in two ways. 1) To improve the grinding of the coffee and 2) To prolong the life of the coffee. If you head into our Bath and London stores you will find a freezer menu. The freezing of coffee affords a lot of flexibility which in turn affords the exploration of more expensive coffee without the concern of wasting coffee that is quickly passing through its quality window. This doesn’t just allow for cafes to make high scoring interesting coffee available at all times, it naturally also increases the range available. Many home brewers have been utilising the approach in the same way. It is also really nice to be able to put aside the coffees you love the most to brew and enjoy at a future date. Of course, most of us only have so much room in our freezer!!
There are still unknowns around frozen coffee. I am still slightly confused by the results of some of the green coffee storage. There is a limit on how long freezing will likely hold quality, not one we know for sure. However, what is more curious is how the coffee can change in the freezer. Sometimes I prefer the coffee after it's been in a freezer as green coffee for a year in comparison to the fresh coffee. Others have started suggesting simple maths for how the roasted coffee may still age even if at a greatly reduced rate. I.e. that freezing roasted coffee one week from roast will not be fully “stopped in time” but rather will continue to age at a greatly reduced rate. As with all coffees, it's complex and there is still much that we are all discovering, but we also adopt processes and techniques that repeatedly display value. Freezing is proving to be one of those techniques.
Best,
Maxwell