For a number of years there has been a war among coffee gurus over the best way to store roasted coffee. There are pro-freezer proponents, pro- refrigerator proponents and dark cabinet proponents. The proponents are all dogmatic and have no respect for each other’s opinion. Periodically, a new opinion appears and the war erupts again.
Humans use two methods of decision making, intuition and logic. It turns out that humans make most of their daily decisions based on intuition. Intuitive decision making is quick and almost automatic. . Intuition usually works just fine but sometimes it fails us. Logical decision making takes time and effort.
Psychologists that study decision making have shown that when we make intuitive decisions we engage in confirmation bias. If we have intuited a decision, we look for sources of confirmation excluding sources which contradict our decision. An example in the political arena would be watching either CNN or Fox News, but not both. “If we think that we have reasons for what we believe, that is often a mistake. Our beliefs and our wishes and our hopes are not always anchored in reasons”. Daniel Kahneman, Princeton University (Nobel Prize in behavioral psychology)
Which gets us back to storing roasted coffee. The amazing thing about storing coffee opinions is that they are almost all based on intuition. For example, if a person thinks that freezing cracks roasted coffee beans they are opposed to freezing. They don’t know for a fact that freezing cracks coffee beans but believe it will, even though they can’t tell for sure because roasting has already cracked the beans.
In another example, a coffee guru, Dr. Chahan Yeretzian states that the coffee aging process is considerably slowed as you cool down the temperature. However, he states that the small benefits you get from impeding the aging process are more than offset by the risk of structural damage to the coffee as well as the possibility of odor contamination and staling by condensation (warm air condenses on cold coffee beans creating moisture, the sworn enemy of coffee freshness). 5 Incredible Myths of Coffee Freshness, Revealed
. Sprudge 23 September 2015 Notice he states a fact, (aging is slowed down) but then states two intuitive suppositions – risk and possibility.
Fortunately logical decision making may have ended the war. Dr. Christopher H. Hendon, the author of Water for Coffee
shared his research at a Specialty Coffee Association symposium in 2017. Based on his research he concluded that:
“Everything happens a lot slower at low temperatures… for every 10 ºC you cool something down, most of the processes occurring in the bean occur at half the rate. So cooling of coffee should prevent chemical reactions that occur over time (like staling or aging), by making them proceed extremely slowly. The other key here is that some processes require some input of energy to even get going. Often that happens at room temperature, but something like the staling process may never occur in a freezer if the coffee is stored appropriately.”
He also cautioned that:
“Most ‘normal’ folks who freeze things are terrible with their protocol. Lots of water exposure. Lots of poorly sealed bags. If that is the case, the coffee will uptake the smells produced by frozen fish sticks and other things…. not good. Simply being mindful is enough to not have these problems.”
He suggests that consumers should use home vacuum sealing machines to prevent water exposure.
In addition to Hendon’s research other researchers have concluded that
:,,,grinding cold results in a narrower particle size distribution, and reduced mean particle size.”Erol Uman
et al.The effect of bean origin and temperature on grinding roasted coffee Scientific Reports/ April 2016
The benefit of more uniform coffee grounds is that flavors from larger particles (under extraction) and smaller particles (over extraction) are minimized.
Putting all of this logic together it appears intuitively that you should freeze your coffee beans in an airtight container, grind them frozen and brew them immediately after grinding.