Non-Irradiated Kosher Cream of tartar powder (potassium hydrogen tartrate) or tartaric acid, is an effervescent acid obtained as a by-product of wine making. The acidic powder is used for culinary and other household purposes, among them: stabilizing egg whites and increasing their heat tolerance; preventing sugar syrups from crystallizing; reducing discoloration of boiled vegetables. Cream of tartar is widely distributed by nature in many fruits, but is usually obtained as a by-product of wine making. During the fermentation of the grapes, tartar crystallizes in the wine casks. The crystals are collected and purified to produce the white, odorless, acidic powder.