One note, and the way I do it...

First the note. The roasting reactions that produce CO2 have occurred by the time the roast has cooled. Therefore would not be subject to the 1/10th rule, it is just a matter of gas diffusion in a porous medium. This would be slowed by freezing but not halted. Which leads to...

The way I do it is with a food saver counter top vacuum setup. In all of the batches I have received from many roasters only one that made a darn fast trip and arrived 2 days post roast ever out gassed enough to even soften the vacuum under the seal, and this is sealing the original 1 lb bags right in the food saver. I can blow a 1 lb bag in 3-5 days so I figure unsealing that and using it thawed will be no problem. If you drink less then open the bag and make two small .5 lb pouches. BTW back to the one roast that did out gas and slightly break vacuum, I had to wait another day after thawing to really use it. It was still way to lively to brew even after a month in the freezer above my regular fridge.

So couple of thoughts and a data point of dubious quality, but I have frozen coffee for years (vacuum now with the espresso) and will stand by it.

Peppersass wrote:Why tape over the valve? It's supposed to be one-way, and I would think there would be minimal outgassing.

One way valves are not always one way. When you freeze a roaster sealed bag, it will vacuum pack itself most of the time. As the air in the bag freezes, it condenses and will draw a small vacuum. You may suck in freezer air, which is pretty funky stuff.

Peppersass wrote:I still haven't gotten an answer to one of my freezing questions:

When you throw a 12oz or 16oz bag from a roaster in the freezer, then later remove it for use, do you

1) defrost and use the whole bag, or
2) Take what you need for a few days or a week, reseal the bag and throw it back in the freezer, or
3) Break it down into different containers and put what you won't be using back into the freezer?

If #3: Do you break it down while still frozen? If so, what about the potential for condensation and freezer burn? Or, do you let the coffee defrost completely and refreeze the unused portion (seems like a bad idea)?

Once I take coffee out of the freezer, it stays out. All or nothing. That is why I also use a version of #3, I break a pound bag down to two individual containers. I will take one out the night before the morning I am going to use it and let it warm to room temperature but I have also just opened it and dumped it in the grinder and had at it. I would think that allowing it to come to temperature before you open it would be best. I have not done any blind tasting to prove it. Based solely on the amount of condensation dripping from the jar as it warms I would make the leap of logic that having all that water on the glass is far preferable than having it in the coffee.

Well, people have been talking about it already, but i view the major advantage of freezing to be the slowing of CO2 outgassing. I've experimented with a basic CO2 flushing system that replaced the air inside my storage bags with CO2. While it did extend the sweet spot for espresso into the 8-9 day window, the beans outgassed at their normal rate, and my espresso came with less and less crema even though the coffee didn't stale. It was very lever-like, actually.

Since the basic system involved CO2 from a paintball supply store, PVC pipes, and rubber balloons, it was very much in the "useful, but not pretty or easy to use" category. I may go back to it for a round two - CO2 flushing prior to freezing would remove any atmospheric moisture - but for now i'm just freezing excess beans.

Popeye, I have had the same thought about outgassing with my freezer experiments and home roasts. My crude experiments have lead me to believe that when the beans are done degassing they are stale and that a bowl with beans exposed to open air did not deteriorate much or any quicker then same beans in a one way valve bag. If I freeze a roast as soon as it is cooled it stops the degassing and resumes where it left off after warming up.

I have been wondering about flushing the oxygen out of the bag and what that would do to preserving a roast.
So I wonder if degassing is the biggest enemy to fresh coffee and not oxygen. I have no doubt oxygen has its role in hurting the oils but no matter how you store beans oxygen will be present even with vacuum sealing.

IMAWriter wrote:I might try again, but with some sort of vacuum seal device.

Here's what seems to be a very inexpensive way to pump vacuum and seal mason jars, fwiw...


With kind regards,
Josh in CA

gscace wrote:IMO it's a waste of time to vacuum pack coffee if it's fresh from the roaster. The coffee degasses like crazy, so any vacuum you pump is gonna be lost really quickly.

This hasn't been my experience when vacuum-sealing and freezing. I vacuum seal right after I roast, and then freeze. (I got a Foodsaver device as a freebie, along with some bags, helping to clean up after a friend's garage sale.) The sealed coffee makes a very tight irregularly-shaped brick in the vacuum bag, and that doesn't change much until 10 days to 2 weeks down the road. By that time the beanz are loose in the bag, but the bag hasn't blown up into a fat little air-pillow (as it will after 3-5 days if the beanz are vac-packed and then left at room temperature). I suppose it would eventually happen, but I've never had frozen beanz stay around that long before using 'em.

(Editing to add that my freezer is a fridge/freezer combo and I doubt it's as cold as a chest freezer would be.)

As to taste, I'm not sure my palate is good enough to tell much, but they certainly taste fresh to me.

Again, if they're left at room temp it's very different. I used to vacuum-seal my fresh-roasted beanz in a container and leave them at room temp, and in that situation they definitely off-gassed quickly -- after 24 hrs there wouldn't be much vacuum in the container, and sometimes the lid would come right off without having to equalize the pressure at all.

FWIW ...

Josh in CA

We are assuming here that the reduction in the rate of degassing correlates with the reduction in staling. We really do not know this to be true. In my observations, most coffees will peak just after they cease to be obviously degassing, and they will remain at their peaks (but of course will change daily) for several more days.

When I open previously frozen mason jars containing coffee that I froze right after roasting, sometimes I get the "whoosh" sound, indicating some pressurization remaining in the jar, e.g. that the seal was good enough to keep the degassed gas inside the jar (or some of it). Often, I don't observe a "whoosh" sound when I take off the lid; presumably this means the lid didn't seal as well on that particular jar that particular time. But have I noticed any correlation between whether or not gas is retained in the jar, and the quality of the previously frozen coffee in the jar? No, I have not. This could be interpreted in several ways; (1) gas in the jar with the beans is not necessary to preserve the beans; (2) certain jars may have degassed more quickly than others, however the coffee is still preserved because whatever the freezing does to preserve the coffee flavor does not necessarily need to retard degassing also; or (3), I have no taste and can't tell the difference .

Freezing obviously reduces the rate of degassing, and it also preserves the taste of coffee, retarding staling. What we do not know is the relationship of the degassing itself, as an observable phenomena and the staling that we taste when we taste coffee past its prime. Is the retardation against staling, caused by freezing, related to the retardation of degassing, or is the retardation of both simply coincidental and not necessarily related? Does freezing retard one more than it retards the other? Is an observation of how much retardation there is of degassing even relevant in our judgement of how much staling has occurred in the coffee, when attempts have been made to preserve the coffee by freezing?

ken