Perger recently came out advocating grinding from frozen to produce a more modal particle distribution.

Keep your pre-weighed doses in the freezer for higher, tastier extractions (though make sure they're sealed without too much moisture or any oxygen).

from http://www.baristahustle.com/grinder-paper-explained/

For what it's worth, I tried it with an espresso this morning and thought the flavor somewhat cleaner and brighter with less bitterness, but I suspect my results may be due to my grounds starting at a cooler temp than usual. (So the result would be lower extraction.) I suppose the ideal would be to grind from frozen and then let your grounds warm up for some length of time short enough to avoid oxidation but long enough that they are close to room temperature.

I'm curious to hear others' results and would like to keep the focus on the technique rather than any folks' personal opinions on Mr. Perger.

Lots of coverage on this on previous threads such as:

Grind frozen coffee beans

Freezer Hopper for Grinders

Wasn't there a post a couple months ago about heating up the beans (I think it was with a sou-vide setup?) for better extractions?

I've occasionally gone straight from the freezer to the grinder when I had unexpected guests and didn't have enough coffee ready in the cabinet. The downside is that anything that doesn't get used up right away will get condensation and be ruined.

It would have to be a huge difference in taste for me to individually seal up 18g doses for storage in the freezer. Maybe having a jug of liquid nitrogen on the counter would be "easier"??

yakster wrote:Lots of coverage on this on previous threads such as:

Grind frozen coffee beans

Freezer Hopper for Grinders

I think previous discussions were primarily in the context of convenience rather than an improvement in flavor, but those links are certainly worth reading.

There was a previous thread where frozen vs fresh beans were used in an a double blind comparison and I believe frozen actually was preferred or was nearly tied. This data led me to freeze and grind directly from frozen. You have to change grind size as frozen will effectively grind finer.

TrlstanC wrote:The downside is that anything that doesn't get used up right away will get condensation and be ruined.

You'd think so but this hasn't been the case in my experience.

I took the trouble of measuring how much moisture was absorbed by beans that had been repeatedly removed and returned to the freezer. It was negligable, at least in the environment where I brew. And I could detect no discernible difference in taste (blind) between those beans and others that had remained sealed in the freezer.

I've been dosing my beans direct from freezer to grinder for 10 years. Ever since Jim and Ken did their freezing study. Tastes great, makes a great grind, and the beans stay fresh to the bottom of the 1kg bag.

TrlstanC wrote:
I've occasionally gone straight from the freezer to the grinder when I had unexpected guests and didn't have enough coffee ready in the cabinet. The downside is that anything that doesn't get used up right away will get condensation and be ruined.

I freeze and then thaw a couple of days worth of beans at a time, and have never once had a condensation issue.

As beans go from colder to warmer when they are ground, they become more pliable, and seem to produce fewer fines. That is the theory, at least, that explains the following observations, that arise when grind setting is maintained and temperature is varied:

1. Frozen beans flow slowest.
2. Room temperature beans are in between.
3. Warmed beans (by a variety of methods) flow fastest.

What tastes best for a particular bean and roast will depend on your other equipment and preferences. My experiments with microwaving beans (as discussed in this thread) suggested that this practice can help extract more out of lighter roasts, allowing you to grind finer while still getting a reasonable flow rate, and seemingly adding a bit of sweetness and clarity even to immersion brewing.

Conceivably grinding frozen beans could be valuable for darker roasts, when you wish to get a slower flowing shot while keeping things coarser to get a ristretto shot that isn't overextracted. The coldness of the grinds themselves would also help achieve a similar effect. I rarely pull darker roasts any more, so when I do freeze beans (which isn't often, one of the benefits of home roasting) I usually let them warm to room temperature before grinding.

Perger's new goal seems to be to make shots with more fines in them, so for that end I suppose freezing-before-grinding makes sense. I worry that he is letting refractometry rather than taste be his guide in this effort, but I have never tasted any coffee he's made, so maybe that is an uncharitable suspicion.

[creative nickname] wrote:
Perger's new goal seems to be to make shots with more fines in them, so for that end I suppose freezing-before-grinding makes sense. I worry that he is letting refractometry rather than taste be his guide in this effort, but I have never tasted any coffee he's made, so maybe that is an uncharitable suspicion.

There's the thing. Multiple people - including me - measured increase extraction yields from heated beans. (We were grinding finer to get somewhat similar flow rates.) And the flavor effects seemed consistent with increased extraction - more flavor clarity and sweetness.

But now there's a claim that freezing results in higher extraction yields. So I suppose it would be wise to test frozen beans and see if they do extract higher. I suspect that given equivalent grind settings, they may very well extract higher, but given grind size adjustments to produce equivalent flow rates, they will not. I suppose that would make freezing useful if you can't grind fine enough on a grinder (e.g. EK43 or other bulk grinder), but you probably have bigger issues to worry about in that case.