I have never had a jar burst from home roast but I have blown the windows out of a car according to the wife now and then.

I just loosen the ring every few days to let out the excess pressure, no difference than a one way valve bag.

I once participated in a taste test, in which we compared the same coffee, roasted at the same time, then allowed to degas in an open bowl, in a closed jar, and under vacuum for the same three-day period. For comparison, the same coffee had been roasted again the morning of the test. All three test batches were kept in a cool, dark place. The vacuum-packed coffee had the least change in flavor, but to my taste the coffee stored open had more complexity and I preferred it. It's entirely possible, and in fact likely, that this occurred in the first few hours, and that vacuum-packing the coffee the morning after roasting would have produced even better results, but it wasn't part of the test and I haven't done a rigorous comparison with this option. I generally wind up leaving the coffee in an open bowl in a cool, dark, cabinet.

Best,
David

I realize this is an old thread, but I have some interest in furthering the same discussion so perhaps some folks will be interested in reading previous thoughts on the subject.

I think I will retrofit some mason jar lids with the one way valve and test that way of storing my freshly roasted coffee.

Some questions about degassing for anyone kind enough to respond:

Are there any general rules for how long a particular roast needs to degas? Like a Full City needs 3 days but Vienna needs 4 days? How can you tell that a coffee is at it's best point after roasting, only the flavor, or are there other signs that degassing is complete?

How does the coffee being under pressure effect the degassing and flavor? I opened the jars on my home roast several times over the first two days after my last roast. I then left town and they were tightly sealed in new jars for three more days. When I returned home there was an audible pop when the jars opened and some of the roasts had developed visible oil spots on the exterior of the beans. Curious if there is any correlation to the pressure and the oil?

Thanks.

For coffee to be consumed in a week or so, any Tupperware or deli style container works fine. The excess pressure exhausts through the lid, and it's relatively airtight otherwise.

BTW, I really doubt that any reasonable way of storing fresh roasted coffee for a week to ten days will cause skunky aromas. That's more or less the point of home roasting

MattJ wrote:I think I will retrofit some mason jar lids with the one way valve and test that way of storing my freshly roasted coffee.

BTDT. Complete waste of effort

the more I've thought about this the more questions I have...

It doesn't seem logical to me that the one way valve would even work in a can lid. The flexible material of a mylar or plastic bag allows for the bag to suck around the coffee and not allow air to come and go. In a can lid I would assume that the pressure inside would have to stay stable as the walls aren't flexible allowing for a change in volume. In essence the valve cannot work in a can lid it seems to me. Thoughts?

For me, installing one-way valves for home-roast in canning jars is not worth the effort.

I've been using plastic canning jar lids because the regular lids are supposed to be single use and were rusting in the dishwasher. These lids are easier to clean and label, plus I found out that there not airtight so they don't pssst when you open them, ever. This, to me, is fine for storing roasted coffee short-term in the cupboard, but for long-term storage I'll still use lids and bands with the roasted coffee in the freezer. The plastic lids are probably about as effective as a one-way valve would be since the coffee would be off-gassing and most of the transfer would be from inside the jar to relieve the increased pressure to the outside. There's no need to leave the lids loose anymore.



This was my 300 g roast of Colombia Peaberry Los Caracoles ("Snails") del Sur that I really enjoyed brewed and pulled as espresso.