Coffee Foam, it means it is fresh
Coffee Foam: after many years of drinking coffee I have made some discoveries and some observations about how to determine when your coffee is still fresh or when it is way past its prime.
What does it mean?
First of all fresh coffee will bubble and foam up in your French press or in your pour over, this is a good sign and a very good thing as this action releases all the good flavors and oils trapped in the coffee bean. Old coffee will not create this action. The dynamics behind this process is a simple release of Lipids (fatty acids) from the ground beans steeping in the hot water. The Lipids are hydrophobic, in layman terms, they hate water and will react to water by frothing and bonding to the fine coffee grounds, lifting themselves up to the top of the French press or your pour over to get away from the water. This action is a sign of fresh coffee; old, stale coffee will not have this reaction because of the break down of the Lipids oils. The Lipids become heavy and inert with age and as a result start decaying and leaving an unpleasant taste. Once you notice this you can break the “bloom” of the coffee by stirring it in the French press and adding more water, or do what some coffee geeks do, simply skim off the foam with a spoon. A plastic soupspoon works the best for this endeavor giving you a cleaner cup of coffee before you plunge the press.
Once again this all falls under the category of personal taste, try it, if you like it, keep doing it, and if not, at least you adventured out and tried something new.