What is a coffee roast date?

The roast date is the single most important piece of information on a bag of coffee. Unlike an 'expiration' or 'best by' date, which is often arbitrary and set by large-scale manufacturers, the roast date tells you exactly when the coffee was transformed from a raw, green seed into a flavorful, aromatic bean. It is the starting point of the coffee's life cycle.

Immediately after roasting, coffee beans begin to release carbon dioxide—a process known as degassing. This is a natural byproduct of the chemical reactions that occur during the roast. If you brew coffee that is too fresh (less than 24-48 hours off-roast), the excess gas can interfere with the water's ability to extract flavor, often resulting in a harsh, uneven, or 'gassy' cup. This is why many roasters recommend letting coffee rest for a few days.

However, coffee is also subject to oxidation. Once the beans are exposed to oxygen, the volatile aromatic compounds that give coffee its unique flavor begin to degrade. Over time, the coffee will lose its vibrancy, sweetness, and complexity, eventually tasting flat, papery, or stale. While the exact shelf life depends on the roast level and storage conditions, most specialty coffee is at its peak between two and six weeks after the roast date.

When buying coffee, always look for a roast date. If a bag only has a 'best by' date, it is a red flag that the coffee may not be fresh. Specialty roasters take pride in their roast dates because they are transparent about the freshness of their product. They want you to experience the coffee as it was intended, at the peak of its flavor profile.

In practice, the roast date empowers you to manage your coffee consumption. If you buy a bag with a recent roast date, you know you have time to enjoy it. If you find a bag that is several months old, you know it will likely lack the nuance you expect. By paying attention to this date, you ensure that you are always brewing coffee that is vibrant, fresh, and true to its origin.