Grinding whole coffee beans yourself is a given for the freshest cup of coffee at home, but buying beans that are past their prime can sabotage your drink early on. Besides the "best if used by date," which states when you should use the beans for the best quality, there is another date on some bags of coffee that’s even more important.

A "roast date" is a simple date stamped on a bag of roasted coffee beans, which allows you to gauge the best time frame for getting the richest, freshest coffee flavor. Though more of a courtesy than a requirement, most high-quality bags display a roast date that shows on what day the whole beans went through the roasting process.

When coffee beans are roasted, the process of "degassing" begins, which releases the carbon dioxide in the beans. As the coffee ages, more gas gets released, affecting the flavor, crema, and brew times and making a noticeable difference in the taste of your drink, so the sooner you grind your coffee after the roast date, the better.

The general rule is to purchase coffee within 7 to 14 days of the roast date, but the rule of consuming within 14 days can vary, since some beans reach peak performance within 30 days. If you let beans sit around for longer than 14 days, they’re still fine to use; try storing them in an airtight container and grinding them finely to maximize flavor.