Lactic acid bacteria volatile acidity

Lactic acid bacteria are common contaminants of distillers fermentations. E. lactis may produce excessive amounts of volatile acids. Some species convert glycerol to fdpropionaldehyde which may break down to acrolein during distillation, producing an acrid odor. 

The mechanism(s) by which lactic acid bacteria inhibit or inactivate other bacteria is not totally clear. Daly et al. (1972), Speck (1972), and Gilliland and Speck (1972) have cited evidence which suggests that the following may be involved (1) production of antibiotics such as nisin, diplococcin, acidophilin, lactocidin, lactolin, and perhaps others (2) production of hydrogen peroxide by some lactic acid bacteria (3) depletion of nutrients by lactic acid bacteria, which makes growth of pathogens difficult or impossible (4) production of volatile acids (5) production of acid and reduction in pH (6) production of D-leucine and (7) lowering the oxidation-reduction potential of the substrate. 

Lamberet, G., Auberger, B., Bergere, J.L. 1997. Aptitude of cheese bacteria for volatile 5-methyl thioester synthesis. II. Comparison of coryneform bacteria, Micrococcaceae and some lactic acid bacteria starters. Appl. Microbiol. Biotechnol. 48, 393-397. 

Tartaric acid is relatively stable to bacterial activity and can only be metabolized by some Lactobacillus species with the production of acetic acid, lactic acid and succinic acid (Handler 1983). When tartaric acid is metabolised, the volatile acidity increases and the wine acquires an acetic aroma and a disagreeable taste this degradation can be total or partial depending on the bacteria population, but it always decreases wine quality. The tartaric acid degrading capacity is restricted to only a few species Radler And Yannissis (1972) found it in four strains of L. plantarum and one strain of L. brevis. 

Couto, J.A., Campos, EM., Eigueiredo, A.R., Hogg, TA. (2006). Ability of lactic acid bacteria to produce volatile phenols. Am. J. Enol. Vitic., 57, 166-171. 

The interaction between aroma compounds and other wine micro-organisms (e.g. lactic acid bacteria) or with metabolites produced during malolactic fermentation has been studied to a limited extent. Interactions between polysaccharides produced by the most common wine lactic bacteria (Oenoccocus oeni) during malolactic fermentation have been shown to be responsible for the reduced volatility of some aroma compounds in wines (Boido et al. 2002). The possibility of direct interactions between the surface of the bacteria cells and aroma compounds should also be considered since this type of interaction has been found for other food lactic bacteria (Ly et al. 2008). 

Edwards, C.G. and Peterson, J.C. 1994. Sorbent extraction and analysis of volatile metabolites synthesized by lactic acid bacteria isolated from wines. J. Food Sci. 59, 192-196. 

Tracey, R.P. and Britz, T.J. 1989. Freon 11 extraction of volatile metabolites formed by certain lactic acid bacteria. Appl. Environ. Microbiol. 55, 1617-1623. 

Volatile phenols originate from hydroxycinnamic acids (ferulic, p-coumaric, or caffeic acid) by the action of hydroxycinnamate decarboxylase enzyme, which turn the hydroxycinnamics acid into vinylphe-nols (Albagnac, 1975 Grando et al., 1993). Then, these compounds are reduced to ethyl derivatives by vinylphenol reductase enzymes characteristic of species, such as Dekkera bruxellensis, Dekkera anomala, Pichia guillermondii, Candida versatilis, Candida halophila, and Candida mannitofaciens (Edlin et al., 1995 1998 Dias et al., 2003 Chatonnet et al., 1992 1995 1997 Dias et al., 2003), apart from very small quantities produced by some yeasts and lactic acid bacteria under peculiar growth conditions (Chatonnet et al., 1995 Barata et al., 2006 ... 

Hansen, B. and Hansen, A. 1994b. Volatile compounds in wheat sourdoughs produced by lactic acid bacteria and sourdough yeasts. Z. Lebensm. Unters. Forsch 198, 202-209. 

Nakae, T., and Elliott, J. A. (1965). Volatile fatty acids produced by some lactic add bacteria. 

A Sensory properties. Lactic acid bacteria also produce volatile substances, for example, diacetyl and acetaldehyde, that contribute to the typical flavour of cultured buttermilk and yoghurt. Starter cultures also possess some proteolytic and lipolytic activity, which, especially during the maturation of cheeses, contributes to their characteristic flavour. 

The main role of propionic acid bacteria in cheese ripening consists in the utilization of lactate produced by lactic acid bacteria as an end product of lactose fermentation. Lactate is then transformed into propionic and acetic acids and CO2. The volatile acids provide a specific sharp taste and help preserve a milk protein, casein. Hydrolysis of lipids with the formation of fatty acids is essential for the taste qualities of cheese. The release of proline and other amino acids and such volatile compounds as acetoin, diacetyl, dimethylsulfide, acetaldehyde is important for the formation of cheese aroma. Carbon dioxide released in the processes of propionic acid fermentation and decarboxylation of amino acids (mainly) forms eyes, or holes. Propionic acid bacteria also produce vitamins, first of all, vitamin At the same time, an important condition is to keep propionibacteria from growing and producing CO2 at low temperatures, since this would cause cracks and fissures in cheese. 

Tavaria, F.K., et al. (2002) Amino acid catabolism and generation of volatiles by lactic acid bacteria. J. Dairy Sci. 85, 2462-2470... 

Unripe cucumbers, after addition of dill herb and, if necessary, other flavoring spices (vine leaf, garlic or bay leaf), are placed into 4-6% NaCl solution or are sometimes salted dry. Usually, the salt solution is poured on the cucumbers in a barrel and then allowed to ferment and, if necessary, glucose is added. Fermentation takes place at 18-20 °C and yields lactic acid, CO2, some volatile acids, ethanol and small amounts of various aroma substances. Homo-and heterofermentative lactic acid bacteria Uke Lactobacillus plantarum, L. brevis and Pediococ-... 

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