I've been brewing an Ethiopian bean recently on the Fellow Stagg Pour Over, and experienced something interesting. When brewing fresh at home, the coffee has delicious fruit notes. However, I brewed it once and took it in a travel mug to work, while it had the same qualities, the fruitiness tasted stale, and more like "old fruit".
I'm wondering if this is due to the coffee degrading due to travel, or if it has oxidized by the leftover airspace in the cup (note: this particular cup has an air-tight seal for a lid).
To summarize, my question is, does coffee oxidize while traveling, and does the amount of headspace you leave in your travel mug affect how well the coffee travels?
I believe this question has already been answered here