Occurence of lactic acid bacteria in grape must during alcoholic fermentation

abstract

English

Winemaking can be summarized as the biotransformation of must into wine, which is carried out principally by Saccharomyces cerevisiae strains during the primary, i.e. alcoholic, fermentation. A secondary fermentation, the so-called malolactic fermentation (MLF), assures biodeacidification that is also often encouraged, since it improves wine stability and quality. Malolactic fermentation usually takes place after alcoholic fermentation, but may also occur simultaneously with the primary fermentation. During the fermentation, lactic acid bacteria metabolize malic acid to form lactic acid and CO2. Strain of lactic acid bacteria isolated from wine belong to the genera Lactobacillus, Oenococcus and Pediococcus, although MLF is largely controlled by Oenococcus oeni. The aim of this work was to monitor the total number of lactic acid bacteria occurring in grape must during wine production. The study was performed on the white wine grape variety Sauvignon from both organic and integrated vineyards. The isolation of pure cultures of lactic acid bacteria from mixed cultures and subsequently their identification by genus (Lactobacillus) and species-specific PCR (Lb. casei/paracasei, Lb. paracasei, Lb. plantarum a Lb. fermentum) was also subject of the thesis. Of the total number of 24 purified bacterial strains isolated during the alcoholic fermentation, 22 strains were identified as the genus Lactobacillus by the genus-specific PCR and the remaining 2 strains as species Oenoccocus oeni by the species-specific PCR. Subsequently, from 22 bacterial strains of the genus Lactobacillus 9 strains were classified as Lb. paracasei, 7 strains as Lb. plantarum, and 1 strain as Lb. Fermentum. The remaining 5 strains were not identified as any of the tested species by species-specific PCR. Then, the analysis explored the effect of the way of wine growing (organic and integrated) on species representation of lactic acid bacteria in grape must during the primary fermentation. The experimental results show that the method of wine growing had an impact on both the number of viable cells as well as the species representation of lactic acid bacteria during the alcoholic fermentation of grape must. Whereas on the first day of alcoholic fermentation the number of lactic acid bacteria did not differ significantly, in the later stage of primary fermentation lactic acid bacteria developed better in the variety from organic vineyard. Similarly, the species representation varied; in the variety from organic vineyard were isolated all 4 tested species, while in the variety from integrated vineyard were isolated only 2 from the tested species.

lactic acid bacteria, winemaking, wine, PCR

VALICOVÁ, M.; OMELKOVÁ, J.; TRACHTOVÁ, Š.; ŠPANOVÁ, A.

17. 8. 2011

Česká společnost chemická

Praha

0009-2770

Chemické listy

105

Czech Republic

1031

1031

1