Grapes acetic acid bacteria

Gluconic acid Botrytized grapes Acetic acid bacteria Schyzosacchaomyces... 

The ability of 40 strains of acetic acid bacteria isolated from grape must and wine to produce biogenic amines was screened in synthetic medium and wine (Landete et al. 2007b), but no positive results were obtained. No further mention regarding the formation of biogenic amines by acetic acid bacteria was found in the literature. 

Drysdale, G.S. and Fleet, G.H. 1989a. The effect of acetic acid bacteria upon the growth and metabolism of yeasts during the fermentation of grape juice. J. Appl. Bacteriol. 67, 471-481. 

Joyeux, A., Lafon-Lafourcade, S., and Ribereau-Gayon, P. 1984b. Metabolism of acetic acid bacteria in grape must. Consequences on alcoholic and malolactic fermentation. Sci. Aliments 4, 247-255. 

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

In the case of sound fruit, populations of acetic acid bacteria are expectedly low (<100 CFU/g), comprised largely of the single species, G. oxydans, and potentially numerous strains, (Joyeux et al., 1984a Drysdale and Fleet, 1988). Splittstoesser and Churney (1992) report recovery of G. oxydans from New York State grapes at much higher levels, ranging upward to 10 CFU/g fruit. 

Section I, Grape and Wine Microorganisms, describes those microorganisms found in grape must, juice, and wines namely yeasts, lactic and acetic acid bacteria, and molds. Here, taxonomy, metabolism, nutritional requirements, and potential impacts on wine quality are areas of focus. 

Acetic acid bacteria development in grape must 189... 

The isolation of acetic acid bacteria from grape must or wine is carried out by culture on a solid nutritive medium. The composition of the medium varies, depending on the researcher. Nevertheless, taking into account their nutritional demands. 

ACETIC ACID BACTERIA DEVELOPMENT IN GRAPE MUST... 

In addition to acetic acid bacteria, yeasts contaminate grapes. Although alcohol production is limited, these strains do produce small quantities of ethanol directly on extremely rotten grapes or immediately following crushing and pressing. This alcohol is immediately oxidized by acetic acid bacteria. Some musts can therefore have a relatively high volatile acidity before fermentation. 

Acetic acid bacteria multiply easily in aero-biosis, i.e. in grape must or wine at the surface in contact with air, but this is not the case during fermentation. As soon as alcoholic fermentation begins, the environment grows poor in oxygen and the oxidation-reduction potential faUs. 

The development of these acetic acid bacteria is also characterized by acetic acid production. The musts obtained from grapes infected with sour rot can contain more than 40 g of acetic acid and up to 25 g of gluconic acid per liter. Since these bacteria only slightly degrade grape acids, the musts obtained have extremely low pHs. This is the worst form of rot. 

Fig. 10.33. Evolution of gluconic acid concentrations in grapes during development of B. cinerea, or of B. cinerea followed by development of acetic acid bacteria...

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