Lactic acid
Organic acid central to metabolism, industry, and medicine.
Lactic acid is an organic acid with the molecular formula C3H6O3. It is an alpha-hydroxy acid (AHA) and a synthetic intermediate in many organic synthesis and biochemical industries. Its conjugate base is called lactate. Lactic acid is chiral, consisting of two enantiomers: L-lactic acid and D-lactic acid. In animals, L-lactate is produced from pyruvate via lactate dehydrogenase during normal metabolism and exercise. It is also produced industrially by bacterial fermentation or chemical synthesis.
- isolated_by
- Carl Wilhelm Scheele
- discovered_by
- Jöns Jacob Berzelius
- structure_established_by
- Johannes Wislicenus
- role_discovered_by
- Louis Pasteur
Lore & Background
The name reflects the Latin word 'lac,' meaning milk. Due to geographic and infrastructural factors, the Soviet Union and several Warsaw Pact members experienced chronic shortages of citric and malic acid. The Narkomzem invested in developing suitable lactobacillus strains to produce lactic acid from crude molasses feedstock. Lactic acid proved a quarter of the cost of citric acid, and its continued use in some Eastern European and Central Asian food production lends a distinctive flavor. Global demand for lactic acid continues to expand, with an estimated annual growth rate of 5–8% driven by biodegradable plastics, green solvents, and pharmaceutical intermediates. Major producers include NatureWorks LLC, Purac, Galactic, and several Chinese manufacturers.
Reader's Guide
Lactic acid is significant for its roles in metabolism, industry, and medicine. In animals, it is produced from pyruvate during normal metabolism and exercise, and its concentration rises when production exceeds removal. It is a key component of lactated Ringer's solution and Hartmann's solution, used for fluid resuscitation after blood loss. Industrially, it is produced predominantly by bacterial fermentation of carbohydrates, with racemic or enantiopure forms possible. The Soviet Union's investment in lactic acid production addressed shortages of citric and malic acid, and the compound remains distinctive in Eastern European and Central Asian food production. Its growing global demand is driven by biodegradable plastics like polylactic acid (PLA), green solvents, and pharmaceutical intermediates. Lactic acid is also the primary endogenous agonist of hydroxycarboxylic acid receptor 1 (HCA1), involved in inhibiting lipolysis and dampening neuron excitation. Its discovery by Scheele, Berzelius, and Pasteur, and structural elucidation by Wislicenus, mark key milestones in organic chemistry and biochemistry.
Did You Know?
- The conjugate base of lactic acid is called lactate, and the derived acyl group is lactoyl.
- Lactic acid is chiral, consisting of two enantiomers: L-lactic acid and D-lactic acid.
- Lactic acid produced by fermentation of milk is often racemic, although certain bacteria produce solely D-lactic acid.
Frequently Asked Questions
Who is Lactic acid?
Lactic acid is a small organic compound with the formula C3H6O3, classified as an alpha-hydroxy acid. It exists as two chiral mirror-image forms—L-lactic acid and D-lactic acid—and its deprotonated conjugate base is simply called lactate.
What are Lactic acid's powers/role?
In animal cells, L-lactate is generated when the enzyme lactate dehydrogenase converts pyruvate during routine metabolism and strenuous exercise. On the industrial side, it is manufactured via bacterial fermentation or chemical synthesis and serves as a key synthetic intermediate in organic and biochemical production.
How does Lactic acid's story end?
Inside the body, lactate is not a metabolic dead end; it can be re-oxidized to pyruvate or funneled into the citric acid cycle for further ATP generation. In industry, it is polymerized into polylactic acid or converted into pharmaceuticals and fine chemicals, giving it a long afterlife in materials science.
Why is Lactic acid important?
It sits at the crossroads of bioenergetics, medicine, and manufacturing, making it one of the most versatile small molecules in both biology and industry. Its two-enantiomer chirality adds a layer of stereochemical complexity that is critical for drug design and metabolic research.
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