I have been here in New york for a couple of months now and i cannot find Cream of tartar for my chiffon cakes. I want to bake my mother a mother's day cake and the grocery stores i visited do not sell them. Also any store you know that sells large packs of yeasts, 500 gram pack such as Lesaffre or REd Star? i do a lot of bread baking and the larger packs seem more practical for me. I really appreciate if you can tell me.. thanks.