Fermentation industry lactic acid

Lactose is readily fermented by lactic acid bacteria, especially Lactococcus spp. and Lactobacillus spp., to lactic acid, and by some species of yeast, e.g. Kluyveromyces spp., to ethanol (Figure 2.27). Lactic acid may be used as a food acidulant, as a component in the manufacture of plastics, or converted to ammonium lactate as a source of nitrogen for animal nutrition. It can be converted to propionic acid, which has many food applications, by Propionibacterium spp. Potable ethanol is being produced commercially from lactose in whey or UF permeate. The ethanol may also be used for industrial purposes or as a fuel but is probably not cost-competitive with ethanol produced by fermentation of sucrose or chemically. The ethanol may also be oxidized to acetic acid. The mother liquor remaining from the production of lactic acid or ethanol may be subjected to anaerobic digestion with the production of methane (CH4) for use as a fuel several such plants are in commercial use. 

Fermentation of lactic acid to yield propionic acid, carbon dioxide, acetic acid, and succinic acid is important for proper eye formation and flavor development in Emmental, Gruyere, and Swiss-type cheese varieties. This fermentation is associated with Propionibacterium spp. subspecies of Propionibacterium freudenreichii are of greatest significance. These organisms can also be used for industrial production of vitamin Bi2 and propionic acid. 

Although already discovered in 1780 by the Swedish chemist Carl Wilhelm Scheele,who isolated the lactic acid from sour milk, lactic acid has attracted more recently a great deal of attention due to its widespread applications, mainly in food, chemical, cosmetic, and pharmaceutical industries. Also, it has a great potential for the production of biodegradable and biocompatible polylactic acid (PLA) and, besides 3-hydroxypropionic acid, as an intermediate for sugar-based acrylic acid. Lactic acid production can be achieved either by chemical synthesis routes or by fermentative production (lactic acid fermentation). By the chemical synthesis route, a racemic mixture of DL-lactic acid is usually... 

Industrial Fermentation. The primary and largest industry revolves around food products. Milk from cows, sheep, goats, and horses have traditionally been used for the production of fermented dairy products. These products include cheese, sour cream, kefir, and yogurt. More recently so-called probiotics appeared and have been marketed as health-food drinks. Dairy products are produced via fermentation using lactic bacteria such as Lactobacillus acidophilus and Bifidobacterium. Fungi are also involved in making some cheeses. Fermentation produces lactic acid and other flavors and aroma compounds that make dairy products taste good. 

The uniformity in this biochemistry is in sharp contrast with the degrees of freedom one has in choosing the microbes, the acid-neutralizing agent, nutrients, and carbohydrates needed for industrial lactic acid fermentation. Only delicate weighing of the pros and cons of every possibility leads to an economically feasible fermentation. 

Neutralization Lactic acid fermentation inevitably leads to a drop in pH, and without neutralization the microorganism is quickly unable to continue the fermentation, as the environment becomes too acidic. Several bases can be used to neutralize the acidity during fermentation, and the choice of the base will determine the nature of the downstream processing (DSP). Most industrial lactic acid plants use Ca(OH)2 or CaCOa, which results in the production of a large amount of gypsum as a by-product. 

In Europe, formic acid is applied on fresh hay or other silage to promote the fermentation of lactic acid and to suppress the formation of butyric acid it also allows fermentation to occur quickly, and at a lower temperature, reducing the loss of nutritional value. Formic acid arrests certain decay processes and causes the feed to retain its nutritive value longer, and so it is widely used to preserve winter feed for cattle. In the poultry industry, it is sometimes added to feed to kill E. coli bacteria. Formic acid is also used in the production of textiles and leather because of its acidic nature. It is also used as a coagulant in the production of rubber. 

Combining the biodegradability of the polymer matrix with the possibility to improve its physical-chemical and thermo-mechanical performances represents a real opportunity. In addition to poly(e-caprolactone), which is derived from the petrochemical industry, this nanocomposite technology has been extended to other aliphatic polyesters such as poly(a-hydroxyacid)s, the most representative being poly(lactic acid) issued fi om sugar and (poly)saccharides fermentation. Poly(lactic acid) clay nanocomposites produced from renewable (non fossil) feedstock should allow for an interesting valorisation of surplus agricultural products. 

Lactic Acid B cteri. The lactic acid bacteria are ubiquitous in nature from plant surfaces to gastrointestinal tracts of many animals. These gram-positive facultative anaerobes convert carbohydrates (qv) to lactic acid and are used extensively in the food industry, for example, for the production of yogurt, cheese, sour dough bread, etc. The sour aromatic flavor imparted upon fermentation appears to be a desirable food trait. In addition, certain species produce a variety of antibiotics. 

Dry bean curd refuse was used as the substrate in the lactic acid fermentation with simultaneous saccharification (SSF). The dry bean curd refuse was preliminarily sieved under a mesh size of 250 II m. It contained 12.3% water, 4.0% ash, 0.8% lipid, 29.3% protein, 53.6% carbohydrate, respectively, in weight basis. The cellulase derived from Aspergilltis niger with an enzymatic activity of 25,000 units/g (Tokyo Kasei Industry Inc.) was employed as the saccharification enzyme. 

Classical examples of industrial biotechnology include the manufacture of ethanol, lactic acid, citric acid, and glutamic acid. The share of renewables in the feedstock of the chemical industry is expected to increase substantially in the years to come [2-4], A newcomer here is propane-1,3-diol (DuPont/Tate Lyle), with the start-up of industrial fermentation foreseen within one year. 

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