Interested to see if there is any scientific research on impact of freshness using containers.

I would assume that properly packaged canned coffee would last longer. No proof, but Illy in cans tends to "fresh" the moment you open it but age much faster and the "Coffee Freshness System" uses CO2 under pressure to keep coffee fresh for much longer than coffee left out. But, pulling off the nitrogen flush or CO2 under pressure takes a lot more than a $3000 can sealer so not likely something a small roaster can afford.

There is some discussion of this in Espresso Coffee (edited by Illy/Viani). There are references at the end of each chapter that might provide a starting point for looking into this subject.

Here is a table from the book:

Pressino wrote:I think most if not all coffee sold in metal cans is vacuum packed...

This is not correct.

There are lots of roasters that don't spend money for vacuum packing equipment.

The tiny paint tin style cans are often just loaded up and the lid is placed on them.

I don't know too much about it, but can seamers for pull-tab cans don't necessarily have a vacuum or a gas flush.

I haven't bought canned ground coffee for decades, but when I did Folgers, Maxwell House, and I think even Medaglia d'Oro were all vacuum packed...so I guess from the comments that has changed.

Folgers, Maxwell House, and Medaglia d'Oro are are large producers that do their best to provide a consistent product and that undoubtedly includes using whatever was state of the art packaging at the time. I believe the discussion here is more about boutique roasters that use cans.

Oh, good points, guys - I'd assumed we were talking about small roasters. Yes, the super massive mega juggernauts with state of the art factories may well have a gas flush facility, particularly if they are canning ground coffee. Interestingly, though, for some facilities that package pre-ground coffee, they grind it the day before and let it gas out overnight so that the packaging doesn't puff up. Presumably if people are packaging preground into a rigid can, the can is strong enough that the outgassing isn't an issue. Still, if you're buying canned preground coffee with a pull tab lid and the lid hasn't puffed out a little, you'd probably have to be a little worried that they let it outgas before flushing and packaging.