Lactic+Acid

In solution, it can lose a [|proton] from the acidic group, producing the **lactate** [|ion] (to be specific, an [|anion] due to being negatively charged with an extra electron) CH3CH(OH)COO−. Compared to [|acetic acid], its pKa is 1 unit smaller, meaning lactic acid deprotonates ten times as easily as acetic acid does. This higher acidity is the consequence of the intramolecular hydrogen bridge between the α-hydroxyl and the carboxylate group, making the latter less capable of strongly attracting its proton. Lactic acid is [|miscible] with water or ethanol, and is [|hygroscopic]. Lactic acid is [|chiral] and has two [|optical isomers]. One is known as L -(+)-lactic acid or (//S//)-lactic acid and the other, its mirror image, is D -(−)-lactic acid or (//R//)-lactic acid. In animals, L -lactate is constantly produced from [|pyruvate] via the [|enzyme] [|lactate dehydrogenase] (LDH) in a process of [|fermentation] during normal [|metabolism] and [|exercise]. It 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 20 mmol/L during intense exertion. In industry, [|lactic acid fermentation] is performed by [|lactic acid bacteria]. These bacteria can also grow in the [|mouth]; the [|acid] they produce is responsible for the [|tooth] decay known as [|caries]. In [|medicine], lactate 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]. It is most commonly used for fluid [|resuscitation] after blood loss due to [|trauma], [|surgery], or [|burn injury].
 * Lactic acid**, also known as **milk acid**, is a [|chemical compound] that plays a role in various [|biochemical] processes and was first isolated in 1780 by the Swedish chemist [|Carl Wilhelm Scheele]. Lactic acid is a [|carboxylic acid] with the [|chemical formula] C3H6O3. It has a [|hydroxyl] group adjacent to the [|carboxyl] group, making it an [|alpha hydroxy acid] (AHA).



During power exercises such a sprinting, when the rate of demand for energy is high, lactate is produced faster than the ability of the tissues to remove it, so lactate concentration begins to rise. This is a beneficial process, since the regeneration of NAD+ ensures that energy production is maintained and exercise can continue. The increased lactate produced can be removed in a munber of ways like oxidation to pyruvate by well-oxygenated muscle cells or conversion to glucose via gluconeogenesis in the liver and release back intot the circulation.

Polymer precursor
Two molecules of lactic acid can be dehydrated to [|lactide], a cyclic lactone. A variety of [|catalysts] can polymerize lactide to either heterotactic or [|syndiotactic] [|polylactide], which as [|biodegradable] [|polyesters] with valuable (//inter alia//) medical properties are currently attracting much attention. Lactic acid is used also as a monomer for producing [|polylactic acid] (PLA), which later has developed application as biodegradable plastic. This kind of plastic is a good option for substituting conventional plastic produced from petroleum oil because of low emission of carbon dioxide. The commonly used process in producing lactic acid is via fermentation, and, later, to obtain the polylactic acid, the polymerization process follows.

Foods
Lactic acid is found primarily in sour [|milk] products, such as [|koumiss], [|laban] , [|yogurt] , [|kefir] , and some [|cottage cheeses]. The [|casein] in fermented milk is coagulated (curdled) by lactic acid. Lactic acid is also responsible for the sour flavor of [|sourdough] breads. This acid is used in beer brewing to lower the pH and increase the body of the beer. Some brewers and breweries will use food grade lactic acid to lower the pH in finished beers.[// [|citation needed] //] In winemaking, a bacterial process, natural or controlled, is often used to convert the naturally present [|malic acid] to lactic acid, to reduce the sharpness and for other flavor-related reasons. This [|malolactic fermentation] is undertaken by the family of [|lactic acid bacteria].