How do I stabilize a lecithin-based foam? I've made quite a few foams using the standard technique of adding powdered lecithin to my flavor base, and then agitating with an immersion blender in a wide, shallow container, with the blender near the surface so it beats in lots of air. This works ok, but I find the foams don't hold as long as I would like, often just a minute or two. Is there anything I can do to make them more stable for service?
I'd look into:


contaminants
the container you use
lecithin ratio
(air) moisture 
inert gas use (which implies a different technique.


This link on foams to the food science pages at edinformatics looks good. Perhaps it can help you out further.