Malic

Malic is most commonly associated with malic acid, a naturally occurring dicarboxylic acid found in many fruits, especially apples, and used to impart tartness in foods and beverages. The term also covers related salts and esters of malic acid, collectively known as malates.

Chemically, malic acid is 2-hydroxybutanedioic acid and contains a single chiral center, giving rise to enantiomers. The naturally occurring form is L-malic acid (S configuration); the D-enantiomer exists but is less common in nature. In solution, malic acid can lose one or two protons, yielding malate monoanion and malate dianion, with pKa values around 3.4 and 5.1, respectively. Malic salts and esters are widely used in industrial and culinary applications.

In metabolism, malate is a key intermediate of the citric acid cycle (Krebs cycle). It is formed from fumarate and converted to oxaloacetate by malate dehydrogenase, generating NADH in the process. Malate also participates in cytosolic and mitochondrial malate–aspartate shuttles that transfer reducing equivalents between compartments and support gluconeogenesis and energy production.

Uses and regulatory status include its role as a food additive and acidity regulator, often labeled as E296 in the European Union. It contributes sourness and acts to balance flavors in fruit products,confectionery, and beverages. In cosmetics and some pharmaceutical formulations, malic acid serves as a pH adjuster and humectant.

Safety considerations are generally favorable, with typical dietary exposure considered safe. As with other organic acids, high concentrations can cause irritation or discomfort to skin and mucous membranes.