Fermentation of lactic acid

Biacetyl is produced by the dehydrogenation of 2,3-butanediol with a copper catalyst (290,291). Prior to the availabiUty of 2,3-butanediol, biacetyl was prepared by the nitrosation of methyl ethyl ketone and the hydrolysis of the resultant oxime. Other commercial routes include passing vinylacetylene into a solution of mercuric sulfate in sulfuric acid and decomposing the insoluble product with dilute hydrochloric acid (292), by the reaction of acetal with formaldehyde (293), by the acid-cataly2ed condensation of 1-hydroxyacetone with formaldehyde (294), and by fermentation of lactic acid bacterium (295—297). Acetoin [513-86-0] (3-hydroxy-2-butanone) is also coproduced in lactic acid fermentation. 

Effect of bead diameter on lactic acid yield is clearly revealed in Fig.6. The optimum bead diameter for the fermentation of lactic acid for cell entrapped in Ca-alginate is 1.0mm with a yield of 30.27 gL and 96.7%. Increasing bead diameter beyond this value did not improve lactic acid production. Smaller bead diameter yields more lactic acid production, due to an increase in the surface volume ratio [9]. A further increase in bead diameter to 5.0mm results in a decrease of lactic acid production to 17.65 gL or 50.7%. 

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. 

A schematic flowsheet of the fermentation unit with integrated MBSE and MBSS circuit for recovery of acid(s) product from the fermentation broth is presented in Figure 23.5. Martak et al. [73] ran a semicontinuous fermentation of lactic acid with Rhizopus arrhizus with a periodical bleed and feed operation without a decrease in LA productivity for 152 h. Such a process could be integrated with separation of lactic acid, for example, by MBSE studied in ref. [74] or by pertraction [44,45], Recovery of vanilline from a fermentation broth is presented in ref. [75] aiming at formation of an integrated system. A combination of MBSE of phenol from saline solution in HF contactor with bioreactor with Pseudomonas putida to remove phenol is studied in ref. [76],... 

Kondo, K., Otono, T. and Matsumoto, M. (2004) Preparation of microcapsules containing extractants and the application of the microcapsules to the extractive fermentation of lactic acid. Journal of Chemical Engineering of Japan, 37, 1. 

Fermentation of lactic acid with Rhizopus arrhizus in a stirred tank reactor with a periodical bleed and feed operation. Process Biochemistry, 38, 1573. 

The anaerobic fermentation of lactic acid is traditionally performed at up to 50°C over 2-8 d at pH 5.5-6.5 (lactic acid bacteria are highly sensitive to acid). The pH is maintained by titration with a base, usually calcium carbonate. The product concentration is kept below approx. 100 g L 1 to prevent precipitation of calcium lactate, as the separation of a precipitate from the biomass would be too elaborate. The stoichiometric yields are high, of the order of 1.7-1.9 mol mob1 (85-95% of the theoretical yield) but the space-time yield, which is ap-... 

Kamoshita Y, Ohashi R, and Suuzuki T. Improvement of filtration performance of stirred ceramic membrane reactor and its application to rapid fermentation of lactic acid by dense cell culture of Lactoccus lactis. J. Ferment. Bioeng. 1998 85(4) 422 27. 

Swiss cheeses are distinguished from other varieties by different starter cultures used and the subsequent growth of propionibacteria with gruyere cheeses, yeasts and coryneforms. Fermentation of lactic acid and residual sugars by propionic bacteria to propionic acid is vital in flavor development, and follows initial lactic acid fermentation by the starters. The propionibacteria also apparently contain peptidases which release the sweet-tasting amino acid proline, according to some investigators(13), an important Swiss cheese tastant. 

Neuberg s studies of the enzymic fermentation of lactic acid resulted in the introduction of its salts as brake fluids in German artillery pieces during World War I. 

The advantageous use of membranes in the removal of toxic compoimds produced during fermentation has been demonstrated in several fermentation systems. Increased (2.5 fold) volumetric productivities and product concentration yields (fourfold) were reported by Christen et al. [209] in ethanolic fermentations assisted by supported hquid membranes. Increased final product concentrations and yield were also reported by Xavier et al. [134] when comparing membrane-assisted extractive fermentation of lactic acid with conventional fermentations. 

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. 

Furthermore methods for combining the fermentation of lactic acid and production of chemical sequence products derived from lactic acid are required for the development of intermediates and speciality chemicals. A worthwhile approach could be the direct fermentation on organic lactates, such as substituted aminium lactates. 

Martak J, Schlosser S, Sabolova E, Kristofikova L, Rosenberg M (2003) Fermentation of lactic acid with Rhizopus arrhizus in a stirred tank reactor with a periodical bleed and feed operation. Process Biochem 38(11) 1573-1583. doi 10.1016/S0032-9592(03)00059-l Marques DS, Gil MH, Baptista CMSG (2012) Bulk polytransesterification of L-lactic acid esters an alternative route to synthesize poly(lactic acid). J Appl Polym Sci 125 E283-E289. doi 10. 1002/app. 36825... 

In addition to alcohoHc fermentation, a malolactic fermentation by certain desirable strains of lactic acid bacteria needs to be considered. Occasionally, wild strains produce off-flavors. Malolactic fermentation is desirable in many red table wines for increased stabiUty, more complex flavor, and sometimes for decreased acidity. Selected strains are often added toward the end of alcohoHc fermentation. AH the malic acid present is converted into lactic acid, with the resultant decrease of acidity and Hberation of carbon dioxide. Obviously this has more effect on the acidity the more malic acid is present, and this is the case in wine from underripe, too-tart grapes. Once malolactic fermentation has occurred, it does not recur unless another susceptible wine is blended. 

Cells of microorganisms have constituted a portion of human food siace ancient times. Yeast-leavened baked products contain the residual nutrients from the yeast cells destroyed duriag bakiag (see Bakery processes and leavening agents). Cultured dairy products, such as yogurt, buttermilk, and sour cream, contain up to lO cells of lactic acid bacteria per gram (19) (see Milk and milkproducts). Other examples of fermented foods consumed siace early times iaclude fermented meats, fish, and soybean products. 

Lactic acid [50-21-5] (2-hydroxypropanoic acid), CH CHOHCOOH, is the most widely occurring hydroxycarboxylic acid and thus is the principal topic of this article. It was first discovered ia 1780 by the Swedish chemist Scheele. Lactic acid is a naturally occurring organic acid that can be produced by fermentation or chemical synthesis. It is present ia many foods both naturally or as a product of in situ microbial fermentation, as ia sauerkraut, yogurt, buttermilk, sourdough breads, and many other fermented foods. Lactic acid is also a principal metaboHc iatermediate ia most living organisms, from anaerobic prokaryotes to humans. 

Polylactide is the generaUy accepted term for highly polymeric poly(lactic acid)s. Such polymers are usuaUy produced by polymerization of dilactide the polymerization of lactic acid as such does not produce high molecular weight polymers. The polymers produced from the enantiomeric lactides are highly crystalline, whereas those from the meso lactide are generaUy amorphous. UsuaUy dilactide from L-lactic acid is preferred as a polymerization feedstock because of the avaUabUity of L-lactic acid by fermentation and for the desirable properties of the polymers for various appUcations (1,25). 

Some of the economic hurdles and process cost centers of this conventional carbohydrate fermentation process, schematically shown in Eigure 1, are in the complex separation steps which are needed to recover and purify the product from the cmde fermentation broths. Eurthermore, approximately a ton of gypsum, CaSO, by-product is produced and needs to be disposed of for every ton of lactic acid produced by the conventional fermentation and recovery process (30). These factors have made large-scale production by this conventional route economically and ecologically unattractive. 

The fermentation-derived food-grade product is sold in 50, 80, and 88% concentrations the other grades are available in 50 and 88% concentrations. The food-grade product meets the Vood Chemicals Codex III and the pharmaceutical grade meets the FCC and the United States Pharmacopoeia XK specifications (7). Other lactic acid derivatives such as salts and esters are also available in weU-estabhshed product specifications. Standard analytical methods such as titration and Hquid chromatography can be used to determine lactic acid, and other gravimetric and specific tests are used to detect impurities for the product specifications. A standard titration method neutralizes the acid with sodium hydroxide and then back-titrates the acid. An older standard quantitative method for determination of lactic acid was based on oxidation by potassium permanganate to acetaldehyde, which is absorbed in sodium bisulfite and titrated iodometricaHy. 

The production of soda crackers is also based on a mixed fermentation. Doughs for cracker production are inoculated with very smaH amounts of bakers yeast. During the first 3—5 h of the 18-h fermentation, yeast activity predominates thereafter bacterial fermentation causes a rapid decrease in pH through formation of lactic acid. 

Salts of Organic Acids. Calcium salts of organic acids may be prepared by reaction of the carbonate hydroxide and the organic acid (9). Calcium lactate [814-80-2] is an iatermediate ia the purification of lactic acid from fermentation of molasses. Calcium soaps, soaps of fatty acids, ate soluble ia hydrocarbons, and are useful as waterproofing agents and constituents of greases (9). 

Several carbohydrates such as corn and potato starch, molasses and whey can be used to produce lactic acid. Starch must fust be hydrolysed to glucose by enzymatic hydrolysis then fermentation is performed in the second stage. The choice of carbohydrate material depends upon its availability, and pretreatment is required before fermentation. We shall describe the bioprocess for the production of lactic acid from whey. 

The overall reaction of glucose catabolism to lactate and acetate fermentation from 2 moles of glucose yields 2 moles of lactic acid, 3 moles of acetic acid and 5 moles of ATP, as shown below ... 

---