How do you keep coffee fresh after opening

Remember to seal the packaging bag after taking some coffee out, so the one-way degassing valve would finish its job to keep the freshness of product.

Does ground coffee need to breathe

Roasted coffee cannot be put directly into a sealed package, because the coffee need to "breathe", that is, the carbon dioxide gas will be released.

Why do coffee packs have an aroma hole if it is recommended to store coffee in an air tight container

This is a hole punched before installing the degassing valve, which purpose is to discharge the CO2 released and avoid the oxidation of coffee.