Cream of tartar, more technically known as potassium hydrogen tartrate, is a fine white powder with many culinary applications. It is a byproduct of the winemaking process as the powder forms inside wine barrels during fermentation. It comes from tartaric acid, a naturally occurring substance in grapes and some other tart fruits that in the principle acid in winemaking. It helps to help control the pH of fermenting grape juice (wine) and that also acts as a preservative for the wine.AKSHAR CHEM