How to correctly freeze espresso coffee beans
I often get questions about freezing coffee beans, and thought I should write my advice down so we can refer to it in the future.
Never, ever use normal “freezer bags” that you buy from the supermarket. Never. Here are the problems with them:
- they're usually made from one kind of plastic, and moisture and gases can get through, and you'll have freezer burn flavor in your coffee beans.
- if the plastic is flexible, it's likely a kind of plastic where the plasticizers will exchange with the oils on the coffee beans. Journal article reference.
- the closure is not airtight, so your beans will taste freezer burned.
- Never freeze a coffee bag from a roaster that has a one way valve on it. The one way valve can easily fail due to ice crystal formation and you will get freezer burn flavors in your coffee.
You want to use sous vide bags that were made for both cooking freezing. These are not the same sous vide bags that are used for packaging.
The key attributes of these kinds of bags are:
- they are a sandwich of several kinds of plastics
- the inside (food touching) layer has no plasticizers that can exchange with food oils
- each plastic layer has different properties: by using a sandwich of plastics, the bag can be designed to not let anything through.
- the bag can be melted shut, so that a real seal is achieved.
Here is a typical example of the kind of sous vide bags you want for coffee bean freezing.
To seal the bag, ideally, you'll use a bar sealer like the one from Anova
If you have the space in your house, consider Anova chamber sealer. You can set the vacuum time, to remove most of the air from your bag, but not at lower-than-atmosphere .
You really want something to seal that does *not* remove all the air. Most will. I can't tell from the Anova specs if they allow that (seal without suction). Creating a low pressure environment inside the bag will over-rapidly dry and age the beans.
Storage: you'll want a freezer that is at least -21ºC cool, ideally -28ºC. At those temperatures, the food inside ceases to age.
Bean resting: we've discovered this the hard way, so be warned that beans frozen using this process are not “resting”. They are in suspended animation. Thus, if your beans taste best after 4 or 6 weeks of resting at room temperature, that still needs to happen. If you freeze freshly roasted beans and then make espresso straight from the freezer, your beans will not have ever rested, and will not taste their best.
Much lower budget than a sealer, but it works well, are the IKEA bag clips. I like using them during the day, to reseal my bag without needing to use the sealing unit.
Updated 2025/02/16