Tea leaves contain proteins and amino acids. It is common for these to create bubbles or foam when they come into contact with water. You will notice that Cusa Tea can do this more than some other loose leaf teas, and this is because during the cold-brew step of production, we apply pressure to the water, which breaks open the cell walls of the tea and fruit to allow them to fully steep in room temperature water. The breakage of the cell wall also releases more proteins and amino acids into the water. The fact that you can see the bubbles tells you that your tea contains good amounts of denatured proteins, amino acids and fatty acids, which are all great and healthy things!