Coffee's enemies: Heat, light, moisture, and oxygen. I needed something that would address moisture and oxygen. Heat and light aren't a big deal, as my house doesn't get hot, and my coffee is stored in a light-tight cupboard.
My first experiment, back in 2011 was the Vac Vin Coffee Saver:
|Pic shows grounds being stored in the VacuVin. |
Terrible idea - grounds go off faster than whole beans, plus
more grit is available to get caught in the seal.
But... it didn't take long before I was dissatisfied. Often, I'd open the canister, and discover that the vacuum had been lost overnight. I'd find other storage for my coffee, put it through the dishwasher, then after a few days, it'd happen again.
The best advice I got, was to run a bead of cooking oil (I used a cotton swab) along the two layers of the seals, and that worked pretty well, for a time. After about 2-3 weeks, a piece of grit would get caught in the seals, which let air leak back in. So, I'd brush out the seals, and re-oil them. That level of maintenance isn't the end of the world (I make my coffee using only manual methods), but sometimes the oil would keep it sealed reliably for a few weeks, and at other times, just a few days.
And ... my week of fresh coffee before it started tasting bitter and stale wasn't prolonged, not as far as I could tell. It's better than storing them in an open bin. It is probably even better than storing them in a mason jar on the counter, as the Vacu Vin is darkened - like built in sunglasses for your beans. But beyond that? Nah. After a year or so, I gave the canisters to my brother.
Note: I've seen comments online that suggest that storing beans in a low-pressure container will cause the oils to migrate out (be sucked out??) of the beans, and make them go rancid sooner. As far as I can tell, that's just speculation, with little basis in fact. My beans didn't get the slightest bit shinier or more oily-looking when stored in the Vacu-Vin. I just didn't find that it kept them any fresher than any closed jar.