There are three stereoisomers of tartaric acid: tartaric acid, L-tartaric acid and racemic tartaric acid. Racemic tartaric acid is a mixture of the same amount of dextrosome and levosome whose optical activity counteracts each other. Racemates do not exist in nature and can be synthesized chemically. All kinds of tartaric acid are colorless crystals which are easily soluble in water. Tartaric acid is widely used as an Acidifier in beverages and other foods, similar to citric acid. Tartaric acid and tannin can be used as mordant of acid dyes, as well as in some developing and fixing operations in the photographic industry. Its iron salt is photosensitive, so it can be used to make blueprints. Tartaric acid can complex with many kinds of metal ions and can be used as cleaning agent and polishing agent for metal surface. Potassium and sodium tartrate (Rochelle salt) can be used as ferin reagent, medicine, laxative and diuretic, and intermediate of cinchofen. The crystal has piezoelectric properties and can be used in electronic industry. Therefore, this product is mainly used in beverage, candy, bread and gelatin as sour agent, biochemical reagent, racemic resolution agent and pharmaceutical resolution agent.