Malic acid (1) is a dicarboxylic acid found in unripe fruits and produces a pleasant sour taste.

It was discovered in 1785 in an apple by Carl Wilhelm Scheele, a Swedish researcher born in 1742 and passed away in 1786, author of numerous discoveries including manganese, chlorine, tartaric acid, glycerin and lactic acid, which he simply classified it as apple acid.

In 1787, Lavoisier and his group of researchers attributed the name malic acid to this acid.

In 1834 the chemist Théophile Jules Pelouze (1807-1867) distilled it and discovered two compounds: maleic acid and para-maleic acid.

It is also found in the human body, in citric acid.

Industrialmente si presenta in forma di polvere bianca.

What it is used for and where

Food

It is used in the food industry to give foods a sour taste. Ingredient included in the list of European food additives as E296.

Cosmetics

Buffering agent. It is an iingredient that can bring an alkaline or acid solution to a certain pH level and prevent it from changing, in practice a pH stabiliser that can effectively resist instability and pH change.

Cosmetic safety

Malic acid was an irritant in clinical tests, with less irritation observed when the pH of the applied material increased, did not cause reproductive toxicity, proved to be a strong ocular irritant (2)

Medical

Used to treat xerostomia, a disease that reduces saliva emission from salivary glands (3), fibromyalgia, a disorder that causes musculoskeletal pain and fatigue (4)

Malic acid studies

• Molecular Formula: C₄H₆O₅
• Linear Formula HO₂CCH₂CH(OH)CO₂H
• Molecular Weight: 134.087 g/mol
• CAS: 97-67-6     6915-15-7
• EC Number:   202-601-5 
• PubChem Substance ID 329750312
• MDL number MFCD00064212
• Beilstein Registry Number 1723539

Synonyms:

• DL-malic acid
• Butanedioic acid, hydroxy-
• 2-Hydroxybutanedioic acid
• 2-Hydroxysuccinic acid
• malate
• Malic acid, DL-
• Musashi-no-Ringosan
• alpha-Hydroxysuccinic acid
• Hydroxybutandisaeure
• dl-Hydroxybutanedioic acid
• Caswell No. 537
• Succinic acid, hydroxy-
• R,S(+-)-Malic acid
• 2-Hydroxyethane-1,2-dicarboxylic acid
• Deoxytetraric acid
• hydroxysuccinic acid

References_________________________________________________________________________

(1) L. Guyton de Morveau, A. Lavoisier, C. Berthollet, A. Fourcroy, Méthode de nomenclature chimique, Cuchet, Paris, 1787, p. 150

(2) Fiume Z. Final report on the safety assessment of Malic Acid and Sodium Malate. Int J Toxicol. 2001;20 Suppl 1:47-55. doi: 10.1080/109158101750300946. 

(3) Liu G, Qiu X, Tan X, Miao R, Tian W, Jing W. Efficacy of a 1% malic acid spray for xerostomia treatment: A systematic review and meta-analysis. Oral Dis. 2023 Apr;29(3):862-872. doi: 10.1111/odi.14116.

(4) Ferreira I, Ortigoza Á, Moore P. Magnesium and malic acid supplement for fibromyalgia. Medwave. 2019 May 28;19(4):e7633. Spanish, English. doi: 10.5867/medwave.2019.04.7632.