I remember coffee in tin/steel cans that “whooshed” when you opened them with a can opener. I always assumed that the vacuum was to keep oxygen away from the coffee to keep the coffee fresh. Is that true, or was that marketing hype. If it protected the coffee, what’s the typical shelf-life of coffee after opening?
Today, coffee comes in plastic containers with an aluminum-coated plastic seal. Do they put some inert gas in the container, or is that just plain, old, air?
You have it pretty right. Oxygen will rip into roasted coffee and it goes stale quite quickly. Carbon Dioxide is a perfectly good replacement and so long as you have a reasonably impermeable seal all is good. Nitrogen is likely as good, but my impression is CO[sub]2[/sub] for coffee.
Roasted coffee beans are often sold in bags that have a one way valve in the top. Newly roasted coffee continues to emit CO[sub]2[/sub] for a while, and naturally purges the bag. Enough to keep the coffee good for a week, which is as long as it should be kept anyway after roasting.
For a coffee geek/snob the rule is a week after roasting, 20 minutes after grinding, and 20 seconds after a pour. In reality it is more complex than this. Andrea Illy, the godfather of coffee, claims that properly packed ground coffee can last many months. But once the oxygen gets to it, the clock is ticking fast.
You so have to have the right taste buds for that; I can tell old beans from new, and an old pot from a new one (when we’re talking more than say… an hour old) , but I can’t tell the difference between beans ground say… last night vs. 5 minutes ago.
But yeah, I suspect nowadays it’s probably a combination of inert gas packaging of some kind, combined with supply chain improvements which get the coffee to the consumer faster than before. The supply chain improvements are probably not even intended primarily for freshness, as just to keep the inventory down, but they have the additional benefit of fresher coffee.
I spent several years as a maintenance mechanic on a coffee packaging line. The pouch pack bags were infused with nitrogen. The cans may or may not have nitrogen in the packing depending on the customer who was purchasing the coffee. The coffee packaged in 5# bags was simply folded over tight against the coffee and nothing was added. Such a small amount of oxygen is present that it is not really enough to make the coffee stale as long as it is not circulating with fresh air. The experts in the lab seem to feel adding nitrogen was more of a sales feature than a real necessity and tests showed an imperceptible difference in the coffee after a few months in storage.
Same here.
When Dad opened a new can, the ground coffee would swell and push out of the can. 16 oz instead of 11.5. 