For the smaller, quality-focused roaster, those kinds of calculations may or may not be relevant. But moisture content still plays an indirect role in a roaster’s costs, regardless of whether or not they’re buying a few containers or a few bags.
There is no direct link between a coffee’s quality and its moisture content. A 10% humidity coffee is not necessarily better or worse than a 12% coffee. However, over time, green coffee will gradually lose vibrance. This will eventually result in the dreaded “past crop” flavor, and this process is associated with the drying out of the coffee.
Therefore, even for a small roaster, it’s important to keep track of moisture content. If you paid for an 85-point coffee at 12% moisture, by the time it reaches 10% moisture it may be more like an 83-point coffee. Yet, you still paid 85-point prices for it originally.
By comparing moisture content loss with quality degradation over time, you can make smart buying and consumption decisions with your green lots. And, when combined with water activity measurements, you can even predict the shelf life of your green coffee. Again, precision here is key: you want to track your coffee through a narrow range of percentage points over a long time frame.
Lastly, you may think to yourself that you don’t need to measure moisture content yourself, since your importer supplies those numbers already. Fred cautions against this thinking. He points out that coffee is shipped on water and that ports can often be warm and humid, which will affect moisture readings.
So, if you’re a roaster in a dry part of the United States but your importer is located in New Orleans or Houston, and is taking moisture readings from lots right as they arrive, those numbers might not be applicable to you by the time your coffee arrives at your facility.