Tartaric acid is an organic acid that is present in plants, including grapes, tamarinds, and bananas. It is a diprotic acid, which means that it has two hydrogen atoms on each of its molecules that can be ionized in water. Tartaric acid salts are called tartrates.
The first form of this acid, derived from potassium tartrate, was isolated in the early part of the ninth century by Jabir ibn Hayyan. The Persian-born Hayyan was responsible for a number of firsts in the field of chemistry. Swedish chemist Carl Wilhelm Scheele later developed the modern method for obtaining this substance in 1769.
This acid is naturally-occurring, but can also be synthetically reproduced. Two forms of tartaric acid, levotartaric acid and mesotartaric acid, can be created artificially. The first pure levotartaric acid sample was created by Louis Pasteur in 1847.
One interesting property of tartaric acid is that it is chiral. This means that its internal structure does not have a plane of symmetry, and that it also has a mirror-image that cannot be superimposed. Chiral mirror-images, also known as enantiomers, are often compared to human hands. They are identical in composition, but not in form. The most common reason a molecule displays chilarity is the presence of an asymmetrical carbon atom, which is a carbon atom that is attached to four other atoms or groups of atoms.
The most common use of tartaric acid is as a food additive. It is often added to certain kinds of candy to give it a sour taste. Cream of tartar, known chemically as potassium bitrate, is typically used to stabilize egg whites, and as an active ingredient in baking powder. This acid is also found in wine, and is responsible for wine diamonds, which are small potassium bitartrate crystals that occasionally form on wine corks.
This substance is also used as an emetic to induce vomiting, and as a laxative. In addition, it functions as an antioxidant. This means that it limits or prevents the oxidization of molecules in the body, in order to prevent the formation of free radicals.
High levels of tartaric acid can be dangerous, because it can act as a muscle toxin. When ingested in certain amounts, it inhibits the creation of malic acid, and an overdose can cause paralysis or death. A lethal dose in humans is approximately 7.5 grams (g) per kilogram (kg). This means that a human weighing 70 kg would need to ingest at least 500 g of it, for it to become toxic.