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Malic acid

Malic acid has been employed for many years in the food industry as an acidifier and numerous means for preparing the acid have been devised such as by fermentation or, more commonly, by hydration of maleic acid. L-malic acid is one of the acids present in musts and wines, together with tartaric acid, citric acid, and much smaller amounts of oxalic acid, uronic acid, succinic acid, lactic acid, acetic acid, glioxalic acid, glyceric acid, pyruvic acid, oxaloacetic acid, alpha-ketoglutaric acid, etc. Synthetic D,L-malic acid, which is easily obtainable, is especially used for this purpose. alic acid is produced synthetically by catalytic oxidation of benzene to maleic acid, which is converted to malic acid by heating with steam under pressure. On the other hand, natural L(-)-malic acid can only be isolated from suitable fruit, via the sparingly soluble calcium salts of the acid. (R)-malic acid [D-(+)-malic acid] is an unnatural malic acid and is useful as a precursor for the synthesis of various chiral compounds such as an optically active isoserine, an optically active pantolactone, an optically active beta-lactam intermediates and an optically active pheromones. Malic acid plays a critical role in producing energy in the cell. The combination of malic acid and magnesium helps combat fatigue.

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