Industrial fermentation lactic acid production from

PLA is finding a wide range of uses, both as a moulded product for the packaging sector, as a film for wrapping and lamination applications, as a fibre fill (pillows/duvets etc.), as a foam, and as a spun textile fibre. Lactic acid produced from microbial fermentation of starch also has many other industrial opportunities, as it is a useful base chemical feedstock for a range of applications. Lactic acid can be chemically converted to propylene glycol, the base for a range of... 

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... 

Chemical synthesis of lactic acid from lactonitrile is the major alternative process for manufacture in competition with fermentation lactic add. In 1995, synthetic lactic acid accounted for about 50 % of the total world lactic acid production (Litchfield 1996). The advantage of the chemical synthesis route is the ease of obtaining a highly purified lactic acid which is required for many industrial products. The synthetic lactic acid is a racemic mixture (DL), whereas fermentation lactic acid may be selectively D(—) or L(-t) or DL depending on the organism catalyzing the conversion. Controlled optical purity as well as... 

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. 

A new method for the preparation of soy sauce has been developed. The new scaled-up method divides the moromi process into two processes autolysis and fermentation. Because of the utilization of high temperatures, the new process permits the production of a NaCl free autolyzate from koji. Division of the fermentation process into two separated processes permit better control of lactic acid fermentation and alcohol fermentation processed which used to require great skill. The new scale-up procedure for soy sauce production yields a product in half the time required by the traditional (conventional) method and still produces a soy sauce with high levels of the desirable Bavor component, glutamic acid. Utilization of this protocol by the soy sauce producing industry should have significant economic impact to bo producers and consumers. 

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. 

The production of substances that preserve the food from contamination or from oxidation is another important field of membrane bioreactor. For example, the production of high amounts of propionic acid, commonly used as antifungal substance, was carried out by a continuous stirred-tank reactor associated with ultrafiltration cell recycle and a nanofiltration membrane [51] or the production of gluconic acid by the use of glucose oxidase in a bioreactor using P E S membranes [52]. Lactic acid is widely used as an acidulant, flavor additive, and preservative in the food, pharmaceutical, leather, and textile industries. As an intermediate product in mammalian metabolism, L( +) lactic acid is more important in the food industry than the D(—) isomer. The performance of an improved fermentation system, that is, a membrane cell-recycle bioreactors MCRB was studied [53, 54], the maximum productivity of 31.5 g/Lh was recorded, 10 times greater than the counterpart of the batch-fed fermentation [54]. 

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