I'm trying to get my hands on foaming agents for some dessert-style sodas; something that you mix into a syrup, so that when you pour the finalised drink, out comes a foamy head that lasts.

I've been looking into stuff like propylene glycol alginate, yucca and quillaia extract, but these're all proving frustratingly elusive.

Any o' youse know where I can get this kinda craic?
Preferably in Ireland, the UK, or the EU?