I had never frozen roasted beans, but recently watched James Hoffmann video posted March 2020 about freezing, and bought a vacuum sealing machine. I vacuum sealed and froze some beans for pour-overs, and the taste difference, if any after freezing, was nominal. But today we pulled some shots on Decent Londinium profile with beans that had been frozen after one week of roasting, and only one week in freezer before thawing overnight, and the taste was really off.

We had pulled some shots with this coffee before freezing, and it was flavorful, but we pulled three shots today and although the shot profiles looked good, the taste was noticeably different, to the point of bitterness and unacceptable aftertaste.

My son ran out of the house to the local roaster and bought a new bag of beans. Does freezing beans not work for espresso, or are we looking at some other currently unknown cause for today's awful tasting shots, everything else seemingly being equal with Decent.

I've been freezing/vacuum sealing roasted coffee for espresso & brew for over 10 years. Some of mine stay in the freezer for 4-6 months without any drastic changes. Lots & lots of threads on this you can read through after an H-B search on the subject. Are you freezing them in your fridge freezer where the temp may fluctuate quite a bit? What were the beans?

When I do freeze, I grind the frozen beans straight out of the freezer. You may need to adjust the grind since frozen beans will grind differently. Like John I have been happy with my experience.

+1

I think thawing changes the bean, and possibly ages it faster (similar to veggies). Also, definitely never freeze, thaw, and refreeze.

Separately, my opinion, take it for what it's worth, I think that vacuum sealing coffee that comes from an opened bag of coffee is a mistake. Freezing coffee in the original bag completely limits the exposure to air. Opening a bag of fresh coffee and then vacuum sealing forces the coffee to be exposed to air multiple times, thereby causing it to stale faster. If you want to freeze beans from an opened bag, just put the beans in an airtight jar and call it a day - don't vacuum seal them.

Auctor wrote:I think thawing changes the bean, and possibly ages it faster (similar to veggies). Also, definitely never freeze, thaw, and refreeze.

Separately, my opinion, take it for what it's worth, I think that vacuum sealing coffee that comes from an opened bag of coffee is a mistake. Freezing coffee in the original bag completely limits the exposure to air. Opening a bag of fresh coffee and then vacuum sealing forces the coffee to be exposed to air multiple times, thereby causing it to stale faster. If you want to freeze beans from an opened bag, just put the beans in an airtight jar and call it a day - don't vacuum seal them.

Do you have any data to back up your opinions? Just wondering... because I have also been freezing coffee beans for many years, first in ziplocks and more recently in vacuum-sealed bags. I have never observed the negative outcomes that you warn against, even when I open vac-sealed bags several times and then reseal/refreeze them. In my kitchen, coffee invariably stales faster at room temperature than when frozen.

This makes sense from a scientific standpoint: cooling slows down all chemical reactions, including coffee bean staling.

I'll admit that my veggie analogy is a bit of a stretch, since veggies have way more water content than a coffee bean. But my data comes from opening a bag of coffee and testing some single dose scenarios (keeping it in the freezer the whole time, thawing it over a day, keeping them out the whole time, using the same airtight jars). Until a few weeks ago, I only drank coffee from one bag at a time, so I could easily taste if there were differences over the course of days.

Much as I would love to get more scientific about this, I don't know how we can convert taste of the coffee (and staleness) into numbers or a scientific test (and EY and TDS while interesting are not yet to my knowledge settled sciences). And there's also how peoples palates can be different. For example, I took a tasting course yesterday and while I could easily appreciate that the coffee was smooth, light, a bit bright, and clean, I couldn't for the life of me taste the fruitiness (which apparently was very explosive). But, you give me a stale cup of coffee, and I'll immediately tease it out and stop drinking (more so than others at the same table).

I'm not sure this conversation is much different than people who claim that the Monolith Max is so much better than the Flat at teasing out light roasts. Have these comparisons been put in front of an SCA tasting panel? Have the top 100 coffee tasters in the world come together and 90/100 believe the Max is better? Is there scientific bedrock to claim that the larger burrs can somehow do a better job of teasing out the fruit and floral notes? Not really - it's just a bunch of coffee enthusiasts working within the limits of their palates and experience using different grinders to make some (hopefully) informed conclusions.

Auctor wrote:Much as I would love to get more scientific about this, I don't know how we can convert taste of the coffee (and staleness) into numbers or a scientific test (and EY and TDS while interesting are not yet to my knowledge settled sciences). And there's also how peoples palates can be different.

It's not always easy but it is possible to compare coffees in blind tastings. In the case of moving coffee from the freezer and then back again after it warms up it would be simple to arrange a side by side, blind cupping of that coffee with one that stayed in the freezer. You could do it without any help, repeating it multiple times with the same coffee and with multiple coffees in order to achieve some level of confidence that you are actually perceiving an effect -- even if it's just your perception.

Fair point. I'll commit my next bag to run some sort of test and report back. I'll stick with a drip method (cupping or v60) with some different scenarios. Just writing out loud here:

Everything will be sealed in airtight(ish) jars. Tasting cant be blind - my wife already thinks I'm nuts.

Day 1: freshly opened (base case)
Day 2: 1 day frozen and immediately opened, vs 1 day left at room temp
Day 3: 2 days frozen and immediately opened, vs 2 days left at room temp, vs 1 day frozen, 1 day thawed at room temp
Day 4: same as Day 3

And so on...

One flaw I can already note is the design doesn't take into account air exposure due to the scenario where someone: "1) freezes, 2)thaws and expose to air, 3) refreezes, 4)thaws and brew". I'll need to noodle on that. If you see any other flaws here, let me know, I'll look to start this on Monday or Tuesday.

Jim Schulman and Ken Fox did some blind taste testing over a decade ago:
Better Espresso thru Freezing
Freezing Espresso Coffee, Part Two

TL;DR: Comparing coffee that was frozen 1-4 months with fresh,
"There is absolutely nothing in the results that would suggest that the fresh coffee made better espresso."