For the freshest coffee possible, a fully-sealed bag of beans with a one-way valve is the green flag you should look for on the shelves.

This packaging style is optimal for coffee beans as it keeps them safe from excess moisture and air while preserving the environment inside the bag.

This method offers higher levels of freshness and extended preservation so you can make as many cups of coffee from one bag without having to dump any due to diminished quality.

This is because fresh coffee beans naturally release carbon dioxide gas, and that air needs a way to escape the bag. That's where the one-way valve comes in.

These valves allow CO2 to be released without letting in any excess oxygen. Oxygen is a freshness killer for coffee beans, leaving them with a stale, rusty flavor.

So if you don't see a one-way valve, (often small little holes are visible on the front of the packaging) avoid buying the coffee beans as they might end up being old or unsavory.