No, you can not but a MOD can so if you PM one they will.

Te secret of the valved bag is it keeps the internal bag pressure very close to atmospheric or whatever it was vacuumed down to when packed.

There is not much CO2 by the time it is cooled from roast coffee unless there is also O2 present. So over time the bag is basically oxygen free. This is how the Italian bar coffee can be used for 24 months past roast plus 6 months past the expiry date. The initial CO released from incomplete combustion uses the O2 to convert to CO2. The cellulose structure oxidizes and is exothermic so the reaction tends to be self sustaining long enough to deplete the O2.

The people who have done any actual lab testing of valve bags are not and have not ever released all of the data.

Just click the "report post" icon and explain in the comment section. That way none of us are left to guess if you wanted one particular post deleted and not another.

And yes, generally when see nothing but "deleted" in a post, we get rid of it just for continuity sake of rest of the conversation.

OldNuc wrote: The people who have done any actual lab testing of valve bags are not and have not ever released all of the data.

A damn shame for the rest of us!
I'm sure many other consumers have shared the experience of buying valve bagged coffee off the shelf or online and finding it not to perform up to expectations due to being stale. So perhaps it's the non-oxidative staling that's important, too - that freezing seems to help reduce.

The data is considered intellectual property and financially useful to a competitor. Why it is not available by googling is intuitively obvious. The info is actually out there but hides in other industrial data and experience. Many industries are interested in preventing or reducing the rate of oxidation of a product and that info is usually available as generic public domain information. The common methods are low temperature, inert atmosphere, and/or atmosphere removal. Purging with an inert gas requires multiple fill, pressurize, vent cycles to end up with a very low residual O2 content. Once purged final storage at a nominal atmospheric pressure is possible for a very long time with the storage life dependent on the properties of what is being stored.

TomC wrote:Just click the "report post" icon and explain in the comment section. That way none of us are left to guess if you wanted one particular post deleted and not another.

Thanks to everyone who replied.

The post I wanted deleted is the one in which I whinged about not being able to delete. Nothing horrible going on, or anything. It's just that I had discovered a grammatical mistake (as a former English teacher, and a current technical writer, I'm kind of neurotic about catching stuff - I edit my posts all the time), and accidentally hit the quote button, instead of the edit button. So it spawned a new post, with a corrected version of my earlier note. I'm not sure how I missed the fact that it had the pseudo-html-quote-codes in it - well, I do - I'd finished the sidecar my husband made for me. Amazing how a single drink diminishes my ability to notice stuff.

Anyway, I went to delete the accidentally-created post, and when I couldn't, I deleted everything in it, and got kinda whiny. Sorry about that.

Forgive the mess on the table - we are building a computer there. Can't get rid of the packaging, until we know that each of the parts is working, and don't have to RMA anything.

Anyway, I had my first storage cupping this morning. Kinda revealed that I don't know what the heck I'm doing. Things I did wrong:

1. Gently stirring the grounds to get them to sink during the brew process. Tasting meant getting a mouthful of grounds.
2. I ended up pouring each cup through a strainer in an elaborate ritual (strain, clean strainer, clean cup, repeat) because I freaked out about the mouthful of grounds, which meant they had different extractions.

What did I learn? Not what I expected. I detected differences in the flavors, but could not identify which were better/fresh/stale/etc. That means that freezing coffee when it's good and fresh probably doesn't change the flavor for the worse. I was totally unable to detect which coffee had been frozen, at least at this point in the game. It also means that any decent storage is good for coffee that is going to be consumed in a week.

Now that said, I WAS able to detect differences in smells when I opened the coffee storage containers:

The vacuum bag of frozen coffee had the most aroma, followed by the 125ml Fido bale-top canning jar. The room temperature vacuum bags had the next most. The Evak, and the two spice jars had the least smell. Now, that could TOTALLY be the size and shape of the containers. I can get my nose into the bags and the bigger canning jar. The spice jars, my nose only hovered over the top.

Another interesting note: No difference in the amount of aroma between the two room-temp vacuum bags. (One I kept tightly bricked, by vacuuming it each day, the other I let soften after the initial vacuuming when it was packed).

Final interesting note: The vacuum-packed and then frozen coffee was not bricked at all. None of the samples in the freezer were. I don't know if the valve fails in cold temperatures or what, and I didn't quite follow Oldnuc's explanation of what was to be expected. The freezer in question is a big deep-freeze (vertical, with front-opening door). I do not intend to change the vacuuming of the freezer bags or to re-brick them.

My inability to tell the difference in freshness between the different beans is one reason I hope others will do similar experiments. I'm not sure my taste buds are sensitive, or rather, educated enough.

Gas volume decreases with decreasing temperature. The bag will brick unless it leaks. Plain old simple physics, no magic. The valve is only supposed to open to release excess pressure inside of the bag.

CathyWeeks wrote:It also means that any decent storage is good for coffee that is going to be consumed in a week.

A week isn't long enough. I thought you were planning on waiting 4 weeks?

CathyWeeks wrote:The vacuum-packed and then frozen coffee was not bricked at all.

Pretty freshly roasted. Maybe it outgassed enough before it got cold. Or the valves all failed. Next time include some control samples with something inert like marbles.

jpender wrote:A week isn't long enough. I thought you were planning on waiting 4 weeks?

Once a week for four weeks. I have 3 more sets of samples, all packed at the same time the first set I tried today.

jpender wrote:Pretty freshly roasted. Maybe it outgassed enough before it got cold. Or the valves all failed. Next time include some control samples with something inert like marbles.

Excellent idea. Will do.

ETA: I was just surprised, because my room temp samples behaved differently: the vacuumed and then left alone for seven day samples are soft bricks. I would have thought the outgassing would be more likely to halt in the freezer. But the frozen samples weren't just soft bricks when I checked them today, they were downright loose.

OldNuc wrote:Gas volume decreases with decreasing temperature. The bag will brick unless it leaks. Plain old simple physics, no magic. The valve is only supposed to open to release excess pressure inside of the bag.

Real-life example: My mother visited me during a 40-year record low for a Minnesota winter (-25F/-32C). Her tires, which had been pressurized at much warmer temps went low overnight.

My coffee samples were bricked prior to going in the freezer. That tells me that my valves likely failed in those temps. But the bags are RATED for freezer use. Ugh. I'm irritated.