tim... has brought this to us :
Citric acid has long been on my list of items that I want in my cupboard as
cheap generic scale remover, because I don't like the smell of vinegar

but I have never (since about 1970) seen anywhere openly selling it,

so no, I don't have some in my cupboards (I just suffer the smell of the
vinegar)

Homebrew home wine shops stock it.