We recommend that everyone drinks their coffee as fresh as possible, and we roast our coffee at least once a week, sometimes twice a week. Purity subscribers and website customers get our coffee directly from the roaster and always the freshest available-- there is no roast date on the bag, but you can look at the bottom of your bag and calculate the roast date by subtracting 10 months from the expiration date.
After 10 months in nitrogen, our antioxidant levels do test slightly lower than the fresh coffee, but still after 10 months Purity is 0.2ug higher than the average of the brands we tested when fresh (representing 118 [non-soluble] other coffees, including high scoring specialty coffees, which were light roasted resulting in higher acrylamide, which our roast avoids). We have not tested other brands over 10 months, but many are not nitrogenated, so would likely be stale and have lost most of the nutritional compounds.
From our lab testing we have determined that antioxidant levels stay about the same for 4 months in nitrogen, but then start to decrease after 4 months, so we are debating ourselves whether to date the bags best at 4 months. The coffee really does taste fresh and representative of our flavor profile for 4 months in nitrogen and has lost very little of the nutritional aspects, too.
The roast date issue is something that the specialty coffee industry debates as well, and there are no stated standards for the industry. The problem with putting a roast date on the bag is general public perception of a roast date without taking into account the nitrogen flushing. We need to date the bags for our wholesale customers to give them time to sell them, and we are investing in higher barrier packaging to keep the coffees fresh for these customers. We give our wholesalers good pricing on smaller volume, so that they can keep the coffee on their shelves as short a time as possible.
What about a bag that has been opened?
It is important to note that the 10 month expiration date is for unopened bags only. Once a bag has been opened, it is recommended to be consumed within 15 days or else the coffee will begin to stale and lose its health benefits. Given the dates mentioned above, this should be a testament to how well the nitrogen flushing preserves the coffee while the bag remains unopened.