A simple test: If it tastes bitter or flat, then it is too old. Coffee is actually known by connoisseurs as a sweet beverage.
But shhh… you are not supposed to know that. And who doesn’t want you to know? Coffee companies who make their living on convenience. And yes, believing that freshness is as simple as ‘burping’ air out of a coffee container – is convenient. Roasted coffee outgasses after the roasting process with peak flavor typically occurring within 24-48 hours. Within a week the beans become progressively staler with much of the flavor complexity lost. Ground coffee becomes stale in a matter of hours.
Consider then the vacuum packed packets of coffee available in a normal supermarket. Since roasted coffee outgasses after roasting, the whole or ground beans have been left exposed to air for sufficient time for the outgassing to cease Kona Coffee Farm Pictureresulting in the coffee being stale before it is packed.
In contrast, green beans can have a shelf life of one year or longer before any noticeable degradation in quality occurs. Some specialty beans are deliberately aged to bring out desirable taste attributes and in the case of monsooned coffee beans, left semi-exposed to the weather. One would not be mistaken in thinking that there are many similarities between coffee beans and wine with both being heavily influenced by their respective environments. Soil, weather, farming techniques, etc. have dramatic effects on the flavor characteristics of both wine and coffee. But there is one significant difference, wine is better aged while coffee is better fresh. Matt at freshroastsystems.com graciously allowed me to reprint the above, which I feel is an excellent explanation of the “freshness” issue.