lactic acid


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Related to lactic acid: pyruvic acid, Lactic acid bacteria, Lactic acid fermentation

lactic acid,

CH3CHOHCO2H, a colorless liquid organic acid. It is miscible with water or ethanol. Lactic acid is a fermentation product of lactose (milk sugar); it is present in sour milk, koumiss, leban, yogurt, and cottage cheese. The protein in milk is coagulated (curdled) by lactic acid. Lactic acid is produced in the muscles during intense activity by the breakdown of glucose, and may be used by muscle cells as a source of energy. Calcium lactate, a soluble lactic acid salt, is used as a source of calcium in the diet. Lactic acid is produced commercially for use in pharmaceuticals and foods, in leather tanning and textile dyeing, and in making plastics, solvents, inks, and lacquers. Although it can be prepared by chemical synthesis, production of lactic acid by fermentation of glucose and other substances is a less expensive method. Chemically, lactic acid occurs as two optical isomersisomer
, in chemistry, one of two or more compounds having the same molecular formula but different structures (arrangements of atoms in the molecule). Isomerism is the occurrence of such compounds. Isomerism was first recognized by J. J. Berzelius in 1827.
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, a dextro and a levo form; only the levo form takes part in animal metabolism. The lactic acid of commerce is usually an optically inactive racemic mixture of the two isomers.

Lactic Acid

 

(α-hydroxypropionic acid, CH3CH(OH)-COOH), a monobasic hydroxycarboxylic acid; an important intermediate metabolite in animals, plants, and microorganisms.

Lactic acid occurs as colorless water-soluble crystals. It exists in two optically active forms, (−) and (+), with a melting point of 25°–26°C, and in an inactive racemic form, (±), with a melting point of 18°C. The (−) and (+) lactic acids undergo racemization at 130°–150°C and produce salts (lactates) and esters similar to carboxylic acids.

Lactic acid is formed during the fermentation of sugary substances by various species of lactic acid bacteria (for example, during the souring of milk, the pickling of cabbage and vegetables, the aging of cheese, and ensilage). Either a racemate or one of the optically active forms of lactic acid is produced, depending on the species of bacteria and the type of sugar present. The industrial fermentation of cane sugar, dextrose, and maltose by Bacillus Delbrucki yields (±) lactic acid, which is used to delime leather in tanning and for chromate reduction in mordanting chrome. Lactic acid salts are used as mordants in dyeing and printing, and lactic acid esters as varnish thinners.

In animal tissue (primarily muscle), the formation of (+) lactic acid is the final stage in the anaerobic enzymic breakdown of carbohydrates, or glycolysis. In the absence of O2, the amount of lactic acid produced in muscle tissue equals the amount of glycogen lost. (Muscle fatigue is associated with the depletion of glycogen reserves and the accumulation of lactic acid.) In the presence of O2, approximately 20 percent of the lactic acid is oxidized to CO2 and H2O, the energy released is used to convert the remaining lactic acid to glycogen, and the onset of fatigue is more gradual. The reversible reduction of pyruvic acid (pyruvate) to lactic acid (lactate) occurs during the final stage of glycolysis upon the action of lactate dehydrogenase. Plants and microorganisms produce lactic acid by pyruvate reduction.

V. N. FROSIN

lactic acid

[′lak·tik ′as·əd]
(biochemistry)
C3H6O3 A hygroscopic α-hydroxy acid, occurring in three optically isomeric forms:Lform, in blood and muscle tissue as a product of glucose and glycogen metabolism;Dform, obtained by fermentation of sucrose; andDLform, a racemic mixture present in foods prepared by bacterial fermentation, and also made synthetically.

lactic acid

a colourless syrupy carboxylic acid found in sour milk and many fruits and used as a preservative (E270) for foodstuffs, such as soft margarine, and for making pharmaceuticals and adhesives. Formula: CH3CH(OH)COOH
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Key Topics Covered: 1 Introduction 2 Research Methodology 3 Executive Summary 4 Premium Insights 5 Market Overview 6 Industry Trends 7 Lactic Acid Market, By Application 8 Polylactic Acid Market, By Application 9 Lactic Acid Market, By Region 10 Polylactic Acid Market, By Region 11 Competitive Landscape12 Company Profiles
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We are the first company to achieve continuous production of optically pure lactic acid from deproteinised lactose whey at industrial scale.
For data analysis descriptive statistics were used (placebo, median, mean, variance, and standard deviation) in order to compare changes of Lactic acid of heart rate beat and consumption oxygen of myocardial.
Lactic acid bacteria are a major concern in the dressings and sauces industry as these organisms can reduce shelf life and contribute to poor quality.
When the amount of ATP needed cannot be derived quickly enough with traditional oxygen intake and conversion to energy, the body then relies on the anaerobic energy system, which creates as a byproduct lactic acid.
The use of lactic acid has been banned in the foodstuffs after the court found the product unsuitable to eat and it was ruled out in Food Safety & Standard Act of 2006.
So basically, we can have a situation where residual antibiotics in the meat can prevent or reduce fermentation by the lactic acid bacteria, but these concentrations do not effect survival or even multiplication of pathogens," Hanne Ingmer explained.
The combination of sodium benzoate and lactic acid was just as effective as the sodium benzoate-lactic acid-disodium ethylenediaminetetraacetic acid combination against both pathogens, and was more effective than the other coating treatments.
Isolation of lactic acid bacteria using food sources such as curd was carried out.
Compared with the dehydration of lactic acid in liquid phase or supercritical water, yield of acrylic acid was higher in gas phase dehydration reaction (Odell et al.