Grapes lactic acid bacteria

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. 

The sugars in fruits such as grapes are feimented by yeasts to produce wines. In winemaking, lactic acid bacteria convert malic acid into lactic acid in malolactic fermentation in fruits with high acidity. Acetobacter and Gluconobacter oxidise ethanol in wine to acetic acid (vinegar). 

Gao, Y.C., Zhang, G., Krentz, S., Darius, S., Power, J., Lagarde, G. (2002) Inhibition of spohage lactic acid bacteria by lysozyme during wine alchoUc fermentation. Aust. J. Grape Wine Res., 8, 76-83. 

The lactic acid bacteria may cause polysaccharides to be released in a wine (Dols-Lafalgue et al. 2007). These compounds can increase the sensation of volume or body of wines, and can also be polymerized with the grape or wood tannins, reducing sensations of roughness or astringency, and producing more complex flavours. 

Moreno-Arribas, V., Polo, M.C., lorganes, F., Munoz, R. (2003). Screening of biogenic amine production by lactic acid bacteria isolated from grape must and wine. Int. J. Food Microbiol, 84, 117-123. 

Matthews, A., Grbin, P. R., Jiranek, V. (2006). A survey of lactic acid bacteria for enzymes of interest to oenologyAwsri /. Grape Wine Res., 12, 235-244. 

In grapes or grape juices, the tartaric esters may be hydrolysed by enzymes from contaminant fungi or from commercial pectolytic preparations, both with cin-namoyl decarboxilase activity, releasing free hydroxycinnamic acid forms (Dugelay et al. 1993 Gerbaux et al. 2002). However, the tartaric esters are mostly hydrolysed after malolactic fermentation (Hernandez et al. 2006, 2007), it being hypothesised that the hydrolytic activity of lactic acid bacteria follows the completion of malic conversion to lactic acid (Cabrita et al. 2007) (see Table 11.4). 

Costello, P.J., I.ee, T.H., and Henschke, P.A. 2001. Ability of lactic acid bacteria to produce N-heterocycles causing mousy off-flavour in wine. Aust. J. Grape Wine Res. 7, 160-167. 

Lonvaud-Funel, A., Joyeux, A., and Ledoux, O. 1991. Specific enumeration of lactic acid bacteria in fermenting grape must and wine by colony hybridization with non-isotopic DNA probes. J. Appl. Bacteriol. 71, 501-508. 

Maria Rodas, A., Ferrer, S., and Pardo, I. 2003. 16S-ARDRA, a tool for identification of lactic acid bacteria isolated from grape must and wine. Syst. Appl. Microbiol. 26, 412-422. 

Tartaric acid Grapes Degradation Oxidation with high oxygen concentration Lactic acid bacteria Acetic acid bacteria... 

Aroma development from non-floral grape precursors by wine lactic acid bacteria. Food Research International, Vol.42, No. 7, (August 2009), pp.773-781, ISSN 0963-9969... 

Splittstoesser, D.F. and Stoyla, B.O. (1989) Effect of various inhibitors on the growth of lactic acid bacteria in a model grape juice system. J. Food Protect. 52(4), 240-243. Wilson, D.L. (1988) Use of inert gases for wine quality maintenance - recent advances. Proc. 2nd Int. Cool Climate Viticulture and Oenology Symp., Auckland, New Zealand, pp. 251-253. 

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