sqroot3 wrote:for those of you using inert gases to flush your storage vessel, how are you setting up your inert gas? do you have a ready supply of nitrogen?

I use the Private Preserve cans. I had bought a case for wine on the recommendation of a friend, then started using it for coffee, purging my 8oz ball jars before they go into the freezer. When I open and start using a jar I don't re-flush it unless it's a decaf, which goes back into the freezer and might stay there for weeks.

It's ridiculously expensive considering that it's just mostly nitrogen (plus CO2 and Argon in the Private Preserve brand.) But is convenient, and my cost of purging an 8oz ball jar is in the neighborhood of 10 cents*, so it adds maybe a couple percent to my coffee cost. I don't know that it makes a real difference, use it because it's easy to do and figure it can't hurt. When the cans (aluminum) are empty I rip the top off and put them in the recycle bin.


* At bargain prices of ~$80 per case, and figuring about 60+ uses per can.

I'll try tossing some fresh beans into two mason jars - one flushed with inert gas, one not - let them go for a week, and post the results.

aecletec wrote:... Most of the papers of interest to me are behind paywalls but a preview of Espresso Science by Illy listed in increasing protection: air, vacuum, inert gas, pressurised, previous method combined with active packaging.

I noticed a couple references to Illy in this thread, and the Science of Quality does have interesting and relevant info. At one time you needed to spend $100+ on the book, but recently much of it became available online. The section on packaging is here: http://wiki.triestecoffeecluster.com/in ... =Packaging

Thanks for the link!
I'll continue to keep an eye out for suitable compressed inert gas in my area, seems like it's the go.

I have a VacMaster chamber sealer. I've tried vacuum sealing beans but it pretty much ruins them quick. If I open them after a few days, there is a nasty stale smell and they don't taste great. I could use something like -5"Hg, but knowing what it does at -25 or -30"Hg makes me not want to vacuum seal them. I've stuck to Mason jars in the freezer.

I don't think there is really any science behind what Doug proposes. As noted already, what little there is on coffee degradation with storage is done at the consumer level, not specialty. For example, a common metric to determine whether coffee has degraded is the point at which 50% of consumers dislike the flavor. I think most of us would recoil a lot sooner than your average consumer.

That said, I have tried a number of ways in my admittedly non-scientific attempts at finding the best storage solution. Foodsaver bags, Foodsaver mason jars, both in and out of the freezer.

I have found that cold stops the chemical reactions that lead to outgassing -- that is, when I vac seal a bag of coffee just out of the roaster and put it in the freezer, the bag does not show any signs of outgassing. Outside the freezer, in a few days the bag will puff up to bursting.

The evil element in the degradation of flavor compounds is oxidation. Thus, removing oxygen (and energy) is the key. Yes, flushing with an inert gas is great, but not all that convenient, and the gas can get expensive. Another solution I have tried is oxygen scavengers (http://en.wikipedia.org/wiki/Oxygen_scavenger), little packets of stuff (iron?) that oxidizes very quickly, leaving almost no oxygen behind. These are also somewhat costly - the last time I bought them they were $26 for 200 20cc packets, including shipping, so about .13 each. I used 2 in a pint mason jar, vac-sealed, and in the freezer they go. Not sure if they were effective, as the efficiency of the oxidation is impeded by the cold.

After all is said and done, I really cannot find any real benefit to the elaborate rituals I tried. I cannot tell any difference between the beans I vac-sealed in the freezer, the ones I put in mason jars and froze without vac-sealing, and the ones I froze using vac sealing and oxygen absorbers. That is for beans stored about 6-8 weeks. Invariably the last jar used gets as good results as the first (at least in my fallible memory). Note the common element: cold.

Added to the empirical evidence provided by Jim Schulman and others here regarding the benefits of freezing, I really think anything more elaborate is rapidly approaching the point of diminished (as in zero) return.

The question raised in post #1 in this thread had to do with the consequences of opening and re-evacuating repeatedly a container of roasted beans. The obvious answer is when the container is opened it refills with air (21% O2) and this includes the roasted beans. for all the time this new air is in contact with the bean it is oxidizing again. Now if the container is evacuated most but not all O2 is removed. Repeating this process for a pound of beans will result in the last of the beans being repeatedly exposed to fresh air. If the beans are not evacuated there is minimal differential pressure force that will be pushing fresh air into the bean. So best practice would be to evacuate for long term cold storage and then just use them and minimize ambient air currents even if stored in a refrigerator at 40F or so. Bottom line is what Doug said is technically correct and based on the anecdotal information in this thread validated.

Pushing fresh air into the bean? I am not sure what this mean or how the situation would be practically different to not evacuating and opening normally. It's not as though the air remains still if you haven't evacuated the container.
My anecdotal evidence from side by side testing is that day to day use with vacuum storage helps preserve flavour, freezing in air lets flavour degrade but outgassing slows. If it's all mere anecdote then we don't really further our knowledge. We need more testing, but I'm happy to try inert gas on the basis of Illys publication and anecdotes if I can access it reasonably.

stahlee wrote:I have a VacMaster chamber sealer. I've tried vacuum sealing beans but it pretty much ruins them quick. If I open them after a few days, there is a nasty stale smell and they don't taste great. I could use something like -5"Hg, but knowing what it does at -25 or -30"Hg makes me not want to vacuum seal them. I've stuck to Mason jars in the freezer.

I have a VacMaster chamber sealer, too. So far, I've found absolutely no adverse effects from sealing in a bag or a short mason jar at full vacuum, then freezing.

aecletec wrote:I'm happy to try inert gas on the basis of Illys publication and anecdotes if I can access it reasonably.

Looking over the wine preserver website, it doesn't seem clear how they know the oxygen has been flushed out. There are instructions about one long spray followed by four short ones. I was curious how we can know know you've used sufficient gas to displace the oxygen? On the same account, you won't know if you're wasting it by using too much I guess...