tartaric acid

http://www.cellar-homebrew.com/store/product.php?productid=984&cat=0&page=1

A lot of brewing places also sell cheese making supplies.

Thanks nutcakes. Good suggestions.

Have you check homebrew and winemaking shops if you have any in your area? Otherwise you can order it on Amazon, there are a couple of sellers.

I wish to make my own mascarpone - and i have a fabulous lemon dessert recipe but want to try making it using a non-citrus based acid with some less traditional flavourings - like pink peppercorns.
Potassium bitartrate (the hydrogen salt of potassium and tartaric acid aka cream of tartar) isnt suitable unfortunately.

What are you using it for? If to stabilize egg whites, consider using a copper bowl.

Tartaric acid can be cream of tartar when naturally derived from wine. If you have ever seen hard tasteless, crystals in a bottle of wine, especially whites, is most likely the tartaric acid that has fallen out from the wine, usually from temperature fluctuation or age. I organic production, only tartaric acid, or cream of tartar can be derived from organic wine (chipped out of the fermentation vats in vast amounts . . not a fun job). Commercial cream of tartar is chemically derived.