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CAS: 50-21-5
MF: C3H6O3
MW: 90.08
EINECS: 200-018-0
Description
Milk acid is the most widely occurring organic acid in nature.
Due to its chiral a-carbon atom, Milk acid has two enantiomeric forms.
Of these, Milk acid is more important in food and pharmaceutical industries because humans have only L-lactate dehydrogenase.
The chemical behavior of Milk acid is mostly determined by the two functional groups.
Besides the acidic character in aqueous medium, the bifunctionality (a terminal carboxylic acid and a hydroxyl group) allows Milk acid molecules to form ‘‘interesters’’ such as the cyclic dimers, the trimers, or longer Milk acid oligomers.
After Milk acid's first isolation by the Swedish chemist Scheel in 1780 from sour milk, Milk acid has been produced commercially since the 1880s in the United States and later in Europe. Worldwide, Milk acid production was approximately 250,000 metric tons per year in 2012 and is expected to reach 330,000 metric tons by the year 2015, with an average price of 1.25 US$ per kilogram in 2013 (food grade, 80–85 % purity).
Approximately 85 % of the demand for Milk acid is from the food industry.
The primary use of Milk acid is as a pH-adjusting agent in the beverage sector and as a preservative in the food industry.
Milk acid is included in the Generally Recognized as Safe (GRAS) by the U.S.
Food and Drug Administration as a food ingredient and was deemed safe by the European Food Safety Authority as well.
The acceptable daily intake for Milk acid was defined by the Joint FAO/WHO Expert Committee on Food Additives as ‘‘not limited,’’ and Milk acid is also supported by the Scientific Committee of Food.
In recent decades, the consumption of Milk acid due to its novel applications has grown quite rapidly, by 19 % per year.
Nonfood use of Milk acid for polymer production contributes to this growth.
Biodegradable polylactic acid is considered to be an environmentally friendly alternative to other plastics from petroleum.
Milk acid is used in various fields, including drug delivery systems, medical devices, fibers, and packaging materials.
Milk acid can be produced via chemical synthesis or carbohydrate fermentation.
The chemical route has various issues, including toxic raw materials, low conversion rates, and especially the inability to produce the optically pure isomer.
Therefore, approximately 90 % of worldwide is produced by biotechnological processes, namely fermentations using renewable resources, which is relatively fast, economical, and able to supply selectively one or two stereoisomers of Milk acid.
Milk acid is a colorless to yellow odorless syrupy liquid.
Corrosive to metals and tissue.
Used to make cultured dairy products, as a food preservative, and to make chemicals.
Milk acid is an organic acid.
Milk acid has a molecular formula CH3CH(OH)COOH.
Milk acid is white in the solid state and it is miscible with water.
When in the dissolved state, Milk acid forms a colorless solution.
Production includes both artificial synthesis as well as natural sources.
Milk acid is an alpha-hydroxy acid (AHA) due to the presence of a hydroxyl group adjacent to the carboxyl group.
Milk acid is used as a synthetic intermediate in many organic synthesis industries and in various biochemical industries.
The conjugate base of Milk acid is called lactate (or the lactate anion).
The name of the derived acyl group is lactoyl.
In solution, Milk acid can ionize by loss of a proton to produce the lactate ion CH3CH(OH)CO−
Compared to acetic acid, its pKa is 1 unit less, meaning Milk acid is ten times more acidic than acetic acid.
This higher acidity is the consequence of the intramolecular hydrogen bonding between the α-hydroxyl and the carboxylate group.
Milk acid is chiral, consisting of two enantiomers.
One is known as Milk acid, (S)-lactic acid, or (+)-lactic acid, and the other, its mirror image, is d-lactic acid, (R)-lactic acid, or (−)-lactic acid.
A mixture of the two in equal amounts is called dl-lactic acid, or racemic lactic acid. Milk acid is hygroscopic.
Milk acid is miscible with water and with ethanol above its melting point, which is about 16 to 18 °C (61 to 64 °F).
Milk acid has a higher melting point.
Milk acid produced by fermentation of milk is often racemic, although certain species of bacteria produce solely d-lactic acid.
On the other hand, Milk acid produced by anaerobic respiration in animal muscles has the enantiomer and is sometimes called "sarcolactic" acid, from the Greek sarx, meaning "flesh".
In animals, Milk acid is constantly produced from pyruvate via the enzyme lactate dehydrogenase (LDH) in a process of fermentation during normal metabolism and exercise.
Milk acid does not increase in concentration until the rate of lactate production exceeds the rate of lactate removal, which is governed by a number of factors, including monocarboxylate transporters, concentration and isoform of LDH, and oxidative capacity of tissues.
The concentration of blood Milk acid is usually 1–2 mM at rest, but can rise to over 20 mM during intense exertion and as high as 25 mM afterward.
In addition to other biological roles, Milk acid is the primary endogenous agonist of hydroxycarboxylic acid receptor 1 (HCA1), which is a Gi/o-coupled G protein-coupled receptor (GPCR).
In industry, Milk acid fermentation is performed by lactic acid bacteria, which convert simple carbohydrates such as glucose, sucrose, or galactose to lactic acid.
These bacteria can also grow in the mouth; the acid they produce is responsible for the tooth decay known as caries.
In medicine, Milk acid is one of the main components of lactated Ringer's solution and Hartmann's solution.
These intravenous fluids consist of sodium and potassium cations along with lactate and chloride anions in solution with distilled water, generally in concentrations isotonic with human blood.
Milk acid is most commonly used for fluid resuscitation after blood loss due to trauma, surgery, or burns.
Milk acid Chemical Properties
Melting point: 18°C
alpha: -0.05 º (c= neat 25 ºC)
Boiling point: 122 °C/15 mmHg (lit.)
Density: 1.209 g/mL at 25 °C (lit.)
Vapor density: 0.62 (vs air)
Vapor pressure: 19 mm of Hg (@ 20°C)
Refractive index: n20/D 1.4262
FEMA: 2611 | LACTIC ACID
Fp: >230 °F
Storage temp.: 2-8°C
Solubility: Miscible with water and with ethanol (96 per cent).
pka: 3.08(at 100℃)
Form: syrup
Color: Colorless to yellow
Specific Gravity: 1.209
PH: 3.51(1 mM solution);2.96(10 mM solution);2.44(100 mM solution);
Water Solubility: SOLUBLE
Merck: 14,5336
JECFA Number: 930
BRN: 1209341
Stability: Stable. Combustible. Incompatible with strong oxidizing agents.
InChIKey: JVTAAEKCZFNVCJ-UHFFFAOYSA-N
CAS DataBase Reference: 50-21-5(CAS DataBase Reference)
NIST Chemistry Reference: Propanoic acid, 2-hydroxy-(50-21-5)
EPA Substance Registry System: Milk acid (50-21-5)
Milk acid consists of a mixture of 2-hydroxypropionic acid, its condensation products, such as lactoyllactic acid and other polylactic acids, and water.
Milk acid is usually in the form of the racemate, (RS)-lactic acid, but in some cases the (S)-(+)-isomer is predominant.
Milk acid is a practically odorless, colorless or slightly yellowcolored, viscous, hygroscopic, nonvolatile liquid.
Milk acid, CH3CHOHCOOH, also known as 2-hydroxypropanoic acid, is a hygroscopic liquid that exists in three isometric forms.
Milk acid is found in blood and animal tissue as a product of glucose and glycogen metabolism.
Milk acid is obtained by fermentation of sucrose (corn refining), The racemic mixture is present in foods prepared by bacterial fermentation or prepared synthetically.
Milk acid is soluble in water,alcohol,and ether.
Milk acid is used as a solvent, in manufacturing confectionery, and in medicine.
Milk acid is obtained by the lactic fermentation of sugars or is prepared synthetically.
The commercial product is the racemic form.
Milk acid is usually available in solutions containing the equivalent of from 50% to 90% lactic acid.
Milk acid is hygroscopic, and when concentrated by boiling, the acid condenses to form lactic acid lactate, 2-(lactoyloxy)propanoic acid, which on dilution and heat ing hydrolyzes to lactic acid.
Milk acid is miscible with water and with alcohol.
Milk acid is odorless.
Milk acid consists of a mixture of lactic acid (C3H6O3) and lactic acid lactate (C6H10O5).
The commercial product is the racemic form.
Milk acid is usually available in solutions containing 50 to 90% lactic acid.
Milk acid is a multi-purpose ingredient used as a preservative, exfoliant, moisturizer, and to provide acidity to a formulation.
In the body, Milk acid is found in the blood and muscle tissue as a product of the metabolism of glucose and glycogen.
Milk acid is also a component of the skin’s natural moisturizing factor.
Milk acid has better water intake than glycerin.
Studies indicate an ability to increase the water-retention capacity of the stratum corneum.
They also show that the pliability of the stratum corneum layer is closely related to the absorption of Milk acid; that is, the greater the amount of absorbed lactic acid, the more pliable the stratum corneum layer.
Researchers report that continuous use of preparations formulated with Milk acid in concentrations ranging between 5 and 12 percent provided a mild to moderate improvement in fine wrinkling and promote softer, smoother skin.
Milk acid's exfoliating properties can help in the process of removing excess pigment from the surface of the skin, as well as improving skin texture and feel.
Milk acid is an alpha hydroxy acid occurring in sour milk and other lesser-known sources, such as beer, pickles, and foods made through a process of bacterial fermentation.
Milk acid is caustic when applied to the skin in highly concentrated solutions.
Uses
Milk acid is an acidulant that is a natural organic acid present in milk, meat, and beer, but is normally associated with milk.
Milk acid is a syrupy liquid available as 50 and 88% aqueous solutions, and is mis- cible in water and alcohol.
Milk acid is heat stable, nonvolatile, and has a smooth.
Milk acid functions as a flavor agent, preservative, and acidity adjuster in foods.
Milk acid is used in spanish olives to prevent spoilage and provide flavor, in dry egg powder to improve disper- sion and whipping properties, in cheese spreads, and in salad dress- ing mixes.
Milk acid is an organic compound with the formula CH3CH(OH)CO2H.
In its solid state, Milk acid is white and water-soluble.
In its liquid state, Milk acid is clear.
Milk acid is produced both naturally and synthetically.
With a hydroxyl group adjacent to the carboxyl group, Milk acid is classified as an alpha-hydroxy acid (AHA).
In the form of its conjugate base called lactate, Milk acid plays a role in several biochemical processes.
In solution, Milk acid can ionize a proton from the carboxyl group, producing the lactate ion CH 3CH(OH)CO−
Compared to acetic acid, its pKa is 1 unit less, meaning Milk acid deprotonates ten times more easily than acetic acid does.
This higher acidity is the consequence of the intramolecular hydrogen bonding between the α-hydroxyl and the carboxylate group.
Milk acid is chiral, consisting of two optical isomers.
A mixture of the two in equal amounts is called DL-lactic acid, or racemic Milk acid.
Milk acid is hygroscopic.
Milk acid is miscible with water and with ethanol above its melting point which is around 17 or 18°C.
Milk acid have a higher melting point.
In animals, Milk acid is constantly produced from pyruvate via the enzyme lactate dehydrogenase (LDH) in a process of fermentation during normal metabolism and exercise.
Milk acid does not increase in concentration until the rate of lactate production exceeds the rate of lactate removal, which is governed by a number of factors, including monocarboxylate transporters, concentration and isoform of LDH, and oxidative capacity of tissues.
The concentration of blood lactate is usually 1–2 mmol/L at rest, but can rise to over 20mmol/L during intense exertion and as high as 25mmol/L afterward.
In industry, Milk acid fermentation is performed by Milk acid bacteria, which convert simple carbohydrates such as glucose, sucrose, or galactose to Milk acid.
These bacteria can also grow in the mouth; the acid they produce is responsible for the tooth decay known as caries.
In medicine, Milk acid is one of the main components of lactated Ringer's solution and Hartmann's solution.
These intravenous fluids consist of sodium and potassium cations along with lactate and chloride anions in solution with distilled water, generally in concentrations isotonic with human blood.
Milk acid is most commonly used for fluid resuscitation after blood loss due to trauma, surgery, or burns.
Milk acid is an important acidulant with a specific astringent sour taste.
Also has a strong bactericidal effect.
Can be used for Milk acid drinks, cool drinks, cakes, pickle and so on.
Milk acid can make foods slightly acidic without masking the natural flavor of fruits and steamed vegetables.
Therefore, Milk acid is widely used in canned foods such as tomatoes, olive, pickled cucumber and pickled cabbage.
Occurrence
Milk acid is a constituent of wine and sour milk; the two optically active isomers are found in muscular tissues and are formed by the action of lactic acid–producing bacteria in several fermentation processes.
Also reported found in guava, grapes, melon, wheat bread, cheeses, yogurt, milk, cream, buttermilk, egg, cooked beef, cognac, cider, sherry, grape wine, beer, grape brandy, whiskey, cocoa, coffee, tea, mango, sake, wort, dried, bonito, cassava, Bourbon vanilla, chicory root, Cape gooseberry and cherimoya.
Production Methods
1. Starch raw materials, molasses, starch sugar as raw materials, after saccharification with the appropriate acid Milk acid bacteria or Bacillus in the appropriate conditions of fermentation, the calcium carbonate and precipitation, and then dilute sulfuric acid to Milk acid , And then refined after lactic acid products can be obtained.
Starch saccharification ↓ saccharification enzyme ↓ Milk acid bacteria and pressure filtration concentrated cooling acidification bleaching ↓ activated carbon ↓ sulfuric acid pumping vacuum concentration cation exchange anion exchange vacuum concentration decolorization filter finished product purification method: Milk acid has a strong hygroscopicity, concentrated partial Milk acid Acid anhydride, heating itself prone to esterification reaction.
Therefore, even if distilled under reduced pressure, Milk acid is difficult to obtain pure product.
The fraction was fractionated at 13.3 Pa, and the distillate was dissolved with a mixture of equal amounts of ether and isopropyl ether to cool the crystals at an ice salt temperature. Filtered and then repeated twice.
Milk acid can also be crystallized at the dry ice temperature.
The solvent may also be used in a mixed solvent of equal amounts of benzene and diethyl ether containing 5% petroleum ether (b.p. 60 to 80C).
2. There are three methods of producing Milk acid in industry, fermentation, acetaldehyde and acrylonitrile.
The most widely used is the fermentation method, is the raw material containing starch sucrose, beet sugar, molasses or grain starch as raw material, saccharification access lactic acid bacteria, ph = 5, 49 ℃ fermentation 3 to 4 days, with calcium carbonate And, while hot filter, refined with calcium lactate.
And then acidified with sulfuric acid, filtered, the filtrate concentrated, decolorization, impurity that product.
3 synthesis of chemical synthesis of acetaldehyde and acrylonitrile method, the resulting Milk acid DL.
(1) acetaldehyde method to acetaldehyde and hydrocyanic acid as raw materials to produce milk, the hydrolysis of crude Milk acid, crude lactic acid by ethanol esterification and then hydrolysis of lactic acid: acetaldehyde and cold hydrocyanic acid into the reaction And then add the water and sulfuric acid catalyzed hydrolysis of lactic acid; ethanol after esterification distillation of ethyl lactate; finally sent to the concentration of concentrated decomposition of refined milk lactic acid.
(2) Acrylonitrile acrylonitrile hydrolysis of crude Milk acid, and then esterified by methanol after hydrolysis of lactic acid: acrylonitrile sent to the reactor, in the catalytic hydrolysis of sulfuric acid to produce a mixture of Milk acid and ammonium sulfate.
The mixture into the esterification reactor and methanol esterification, separation of ammonium sulfate, the crude ester to send distillation tower, the bottom of the fine ester.
Refined ester distillation tower, heating decomposition, was dilute Milk acid.
Finally, Milk acid is concentrated by vacuum.
3. Tobacco: In the food industry by the glucose, starch, milk fermentation preparation; acetaldehyde and hydrocyanic acid reaction to produce cyanoethanol, and then hydrolyzed to produce crude lactic acid, vinegar lactic acid into ethyl lactate, and then hydrolyzed to pure Milk acid.
Biochem/physiol Actions
In animals, Milk acid is a metabolic compound produced by proliferating cells and during anaerobic conditions such as strenuous exercise.
Milk acid can be oxidized back to pyruvate or converted to glucose via gluconeogenesis.
Milk acid is preferentially metabolized by neurons in several mammal species and during early brain development.
Synonyms
lactic acid
2-hydroxypropanoic acid
DL-Lactic acid
50-21-5
2-hydroxypropionic acid
Milk acid
lactate
Tonsillosan
Racemic lactic acid
Ordinary lactic acid
Polylactic acid
Ethylidenelactic acid
Lactovagan
Acidum lacticum
26100-51-6
Lactic acid, dl-
Propanoic acid, 2-hydroxy-
Kyselina mlecna
Lacticum acidum
DL-Milchsaeure
(+/-)-Lactic acid
598-82-3
1-Hydroxyethanecarboxylic acid
Aethylidenmilchsaeure
alpha-Hydroxypropionic acid
(RS)-2-Hydroxypropionsaeure
FEMA No. 2611
Kyselina 2-hydroxypropanova
Propionic acid, 2-hydroxy-
Purac FCC 80
Purac FCC 88
CCRIS 2951
HSDB 800
(+-)-2-Hydroxypropanoic acid
Lurex
Lactic acid, tech grade
Propanoic acid, hydroxy-
SY-83
DL- lactic acid
NSC 367919
2-Hydroxypropionicacid
AI3-03130
MFCD00004520
HIPURE 88
NSC-367919
.alpha.-Hydroxypropanoic acid
.alpha.-Hydroxypropionic acid
(R)-2-Hydroxy-propionic acid;H-D-Lac-OH
INS NO.270
E 270
(+/-)-2-hydroxypropanoic acid
CHEBI:78320
INS-270
Poly(L-lactide)
3B8D35Y7S4
Lactic acid USP
NCGC00090972-01
Lactic acid, 1.0N Standardized Solution
2-hydroxy-propionic acid
Lactic acid (natural)
E-270
DSSTox_CID_3192
alpha-Hydroxypropanoic acid
C01432
DSSTox_RID_76915
DSSTox_GSID_23192
Milchsaure [German]
Lactic acid [JAN]
Milchsaure
FEMA Number 2611
Kyselina mlecna [Czech]
163894-00-6
Cheongin samrakhan
CAS-50-21-5
Cheongin Haewoohwan
Cheongin Haejanghwan
Kyselina 2-hydroxypropanova [Czech]
EINECS 200-018-0
EINECS 209-954-4
Lactic acid [USP:JAN]
EPA Pesticide Chemical Code 128929
BRN 5238667
lactasol
1-Hydroxyethane 1-carboxylic acid
Biolac
UNII-3B8D35Y7S4
2-Hydroxy-2-methylacetic acid
Lactide Polymer
Chem-Cast
L- Lactic acid
DL-Polylactic acid
Lactate (TN)
Lactic acid,buffered
4b5w
Propanoic acid, (+-)
DL-Lactic Acid, Racemic
(.+/-.)-Lactic acid
EC 200-018-0
Lactic acid (7CI,8CI)
Lactic acid (JP17/USP)
Lactic acid, 85%, FCC
Lactic Acid, Racemic, USP
NCIOpen2_000884
LACTIC ACID (+-)
DL-LACTIC ACID [MI]
Lactic acid, unspecified form
LACTIC ACID [WHO-IP]
(RS)-2-hydroxypropanoic acid
Lactic Acid (Fragrance Grade)
LACTICUM ACIDUM [HPUS]
DL-Lactic Acid (90per cent)
CHEMBL1200559
DTXSID7023192
Lactic acid, natural, >=85%
BDBM23233
L-lactic acid or dl-lactic acid
Lactic Acid, 85 Percent, FCC
LACTIC ACID, DL- [II]
DL-Lactic acid, ~90% (T)
DL-Lactic acid, AR, >=88%
DL-Lactic acid, LR, >=88%
DL- LACTIC ACID [WHO-DD]
Lactic Acid, 10 Percent Solution
HY-B2227
Propanoic acid, 2-hydroxy- (9CI)
Tox21_111049
Tox21_202455
Tox21_303616
BBL027466
NSC367919
STL282744
AKOS000118855
AKOS017278364
Tox21_111049_1
ACIDUM LACTICUM [WHO-IP LATIN]
AM87208
DB04398
SB44647
SB44652
DL-Lactic acid, 85 % (w/w), syrup
Propanoic acid,2-hydroxy-,(.+/-.)-
2-Hydroxypropionic acid, DL-Lactic acid
NCGC00090972-02
NCGC00090972-03
NCGC00257515-01
NCGC00260004-01
26811-96-1
Lactic Acid, 85 Percent, Reagent, ACS
DB-071134
CS-0021601
FT-0624390
FT-0625477
FT-0627927
FT-0696525
FT-0774042
L0226
Lactic acid solution, ACS reagent, >=85%
Lactic acid solution, USP, 88.0-92.0%
Lactic acid solution, p.a., 84.5-85.5%
Lactic acid, meets USP testing specifications
D00111
F71201
A877374
DL-Lactic acid, SAJ first grade, 85.0-92.0%
Q161249
DL-Lactic acid, JIS special grade, 85.0-92.0%
Lactic acid solution, Vetec(TM) reagent grade, 85%
F2191-0200
BC10F553-5D5D-4388-BB74-378ED4E24908
Lactic acid, United States Pharmacopeia (USP) Reference Standard
Lactic acid, Pharmaceutical Secondary Standard; Certified Reference Material
DL-Lactic acid 90%, synthetic, meets the analytical specifications of Ph. Eur.
152-36-3
