L(-)-Malic acid
[CAS# 97-67-6]

Identification

• Classification: Biochemical >> Amino acids and their derivatives >> FMOC-amino acid
• Name: L(-)-Malic acid
• Synonyms: L-Hydroxysuccinic acid; Apple acid
• Molecular Formula: C₄H₆O₅
• Molecular Weight: 134.08
• CAS Registry Number: 97-67-6
• EC Number: 202-601-5
• SMILES: C([C@@H](C(=O)O)O)C(=O)O

Properties

• Solubility: soluble (acetone, dioxane, water, methanol, ethanol)
• Density: 1.6 g/mL
• Melting point: 101-103 °C
• Flash point: 220 °C
• alpha: -2 ° (c=8.5, H2O)

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H315-H319
• Safety Statements: P264-P264+P265-P280-P302+P352-P305+P351+P338-P321-P332+P317-P337+P317-P362+P364

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319
Skin irritation	Skin Irrit.	2	H315
Specific target organ toxicity - single exposure	STOT SE	3	H335
Acute toxicity	Acute Tox.	4	H302
Specific target organ toxicity - single exposure	STOT SE	3	H336
Serious eye damage	Eye Dam.	1	H318

Discovery and Applications

Malic acid was first isolated from unripe apples in 1785 by Swedish chemist Carl Wilhelm Scheele, which is why its name is derived from the Latin word malum (apple). Scheele's work marked the beginning of research into this important acid, which plays a key role in the Krebs cycle - a fundamental process in cellular respiration that produces energy.

L(-)-Malic acid is a naturally occurring enantiomer found in many fruits and vegetables, especially apples, grapes and berries. This chiral molecule gives these foods their sour taste and is a key intermediate in various metabolic pathways. L(-)-Malic acid (C4H6O5) is a dicarboxylic acid in which one of the carboxyl groups is attached to an asymmetric carbon, making it chiral. It appears as a white crystalline powder or granules, has a sour taste and is highly soluble in water. Its chemical structure allows it to interact easily with other molecules, making it a versatile ingredient in a variety of applications.

L(-)-Malic acid is widely used as a flavor enhancer and acidulant in the food and beverage industry. Its tart taste can be used to add a pleasant sour taste to the following products:Soft drinks, juices, and sports drinks use L(-)-malic acid to balance sweetness and improve flavor. Hard candies, soft candies, and jellies benefit from its ability to provide a lasting sour taste. It acts as a leavening agent in baked products, helping to enhance texture and flavor.

In health and nutrition, L(-)-malic acid is valued for its role in metabolism and energy production. It is used in dietary supplements:Supplements containing L(-)-malic acid help boost energy levels by supporting the Krebs cycle. It helps reduce muscle fatigue and soreness after exercise, making it popular among athletes. L(-)-malic acid helps maintain the body's acid-base balance, contributing to overall health. In pharmaceuticals, L(-)-malic acid is used as an excipient in a variety of drug formulations. It enhances the taste of oral medications and helps improve the stability and solubility of active ingredients, thereby increasing their efficacy.

L(-)-Malic acid is a building block for the synthesis of other chemicals, including polyesters and biodegradable plastics. Its reactivity makes it a valuable precursor in chemical manufacturing processes. It is used in cosmetic formulations for its exfoliating properties and ability to adjust pH. L(-)-Malic Acid helps remove dead skin cells and enhances the texture of skin care products, making them more effective and appealing. L(-)-Malic Acid is used as a chelating agent in agricultural applications to help improve the absorption of essential nutrients by plants. This contributes to better growth and yields, increasing agricultural productivity.

References

2005. Production of L-Malic Acid by Permeabilized Cells of Commercial Saccharomyces Sp. Strains. Biotechnology Letters, 27(23).
DOI: 10.1007/s10529-005-3890-3

2013. Metabolic engineering of Aspergillus oryzae NRRL 3488 for increased production of l-malic acid. Applied Microbiology and Biotechnology, 97(20).
DOI: 10.1007/s00253-013-5132-2

2015. Direct fungal fermentation of lignocellulosic biomass into itaconic, fumaric, and malic acids: current and future prospects. Journal of Industrial Microbiology and Biotechnology, 42(4).
DOI: 10.1007/s10295-014-1575-4