How important is roast date?

“What is the roast date?”. It is an important question but not the most important question and it likely will not give you all of the information you are looking for. Roast date versus packaging has been a point of confusion in the coffee world for some years. Smaller roasters often focus heavily on roast date because they transfer their beans directly from their roaster to a non-valve sealed, non-lined paper bag. Larger roasters, who often have industrial degassing bins and air-tight bean-to-grinder-to-bag capabilities, tend to focus on a combination of roast date, process, and storage. Both processes are good. Both processes can produce wonderful coffee, and both processes have different time frames on what would be considered “fresh coffee”. To better understand this, it is necessary to understand what happens while and right after beans are roasted.

During the roasting process, carbon dioxide (CO₂) develops inside the coffee beans. The CO₂ must be released before the beans are brewed or you will end up with an off-tasting, unequally extracted cup of coffee. The CO₂ release process is referred to as degassing. During degassing, which can take up to two weeks, CO₂ is released from the beans and replaced with oxygen. Numerous factors including temperature, humidity, storage, and roast impact the degassing speed. At the other end of the spectrum is oxidization, the process whereby coffee beans absorb oxygen. Beans with too much oxygen are what we would call stale. The roasters challenge is to identify and preserve the beans at their optimal degassed state. Some roasters do this by indicating a roast date and encouraging consumers to drink their coffee within x days of the roast date. Other roasters use valve-sealed (i.e., CO₂ can escape and no oxygen can enter the bag) and sometimes lined packaging to preserve degassed beans at their optimal state.

Roasters that use paper tin-tie bags to store or sell beans likely allow the degassing process to occur in the paper bag. As a result, these beans are likely to be best 1-2 weeks after roasting. Roasters who use valve-sealed bags have most likely allowed the beans to degas to their optimal state prior to bagging. Once placed in a valve-sealed bag or other airtight container, these beans should remain at an optimal or near optimal state for 3-6 months. That said, once a valve-sealed bag is opened, the degassing / oxidization process resumes and, from that point, the coffee will be best if consumed within 1-2-weeks unless the beans are transferred to another or resealed in their current airtight container. If properly stored, the coffee should last for another 6-7 weeks after opening.

At Mills / The Queen Bean, our beans directly transfer from our roaster to a degassing bin and often don’t touch the air until you open your bag. Additionally, we roast multiple times a week and go through coffee so quickly that we personally grind our beans 15-20 minutes before brewing to allow the final bit of degassing to occur before we brew. We wouldn’t give you beans directly from the roaster or roasted the previous day because we would consider those beans unfinished.

 The bottom line is (and this is likely what you were hoping to avoid by asking a seemingly simple question to start!), if you want to know when it is optimal to brew your beans, ask your roaster about their process. They’ll likely love the question – they want their coffee to be one of the best parts of your day.