Tartaric Acid

Tartaric acid, also known as white crystalline dicarboxylic acid, is an organic acid , with the formulaHO2CCHOHCHOHCO2H or simply C4H6O6. It occurs naturally as algol (an impureform of potassium hydrogen tartrate) which is a by-product of the fungus responsiblefor the fermentation of wine , givingwine some of its sharp taste, and is also found in tamarinds . It is added to otherfoods to give an acid taste, and as an antioxidant. Tartaric acid exists as a pair of enantiomers and an achiral meso compound. (+)-tartaric acid commonly occurs in nature and can be found in fruit, and sometimes in wine. Tartaric acid is industrially synthesised as a byproduct during wine making, and it is used in food as an antioxidant and synergist to increase the antioxidant effect of other substances. It is also used as an acidity regulator and sequestrant. Excessive ingestion of tartaric acid results in laxative effects.

Tartaric acid is a chiral compound, meaning that it occurs in multiplethree-dimensional forms, or isomers. This property makes it a useful raw material in organic chemistry for the synthesisof other chiral molecules. The naturally occurring form of the acid is levotartaric or (-)-tartaric acid, also calledd-2,3-dihydroxysuccinic acid or l-2,3-dihydroxybutanedioic acid. The opposite form, dextrotartaric or (+)-tartaric acid, and the achiral form, mesotartaric acid, can be made artificially. The dextro- and levo-forms are said to be enantiomers of each other. The meso- form is said to be a diasteromer of the other twotypes. A mixture of the levo- and dextro- forms is called racemic tartaricacid or DL-tartaric acid.

Tartaric acid was first isolated from potassium tartrate, known to the ancients as tartar, in 1769 by the Swedish chemist Carl Wilhelm Scheele . The chirality of tartaric acid was discovered in 1832 by Jean Baptiste Biot , who observed its ability to rotate polarized light. Louis Pasteur continued this research in 1847 by investigating the shapes of tartaric acid crystals, which he found to be asymmetric. Pasteur was the first toproduce a pure sample of levotartaric acid.

Tartaric acid is a muscle toxin , which worksby inhibiting the production of malic acid , and in high doses causes paralysisand death. The minimum recorded fatal dose for a human is about 12 grams. In spite of that, it is included in many foods,especially sour-tasting sweets. Tartaric acid is a natural crystalline compound found in grapes and has many applications. Tartaric Acid functions as an acidulant in beverges, confectionary products, jams and juices. It enhances and blends in perfectly with natural and artificial flavours in carbonated drinks and fruit juices (natural and artificial). It also gives a fruity after taste to beverages. Tartaric acid controls the pH in wine making. It is the natural agent which provides the acidic characteristic and enhances the fruity flavour.

Important derivatives of tartaric acid include its salts, cream oftartar (potassium hydrogen tartrate), Rochelle salt (potassium sodiumtartrate, a mild laxative ) and tartar emetic (antimony potassium tartrate).