Lactic Acid bacteria
Like yeast, indigenous lactic acid bacteria in wine originate from grapes. The species diversity is relatively high in the grapes and juice; however, as the environment changes (by the addition of SO2, extraction of phenolic compounds, presence of ethanol, etc.), the population decreases.
After alcoholic fermentation, usually only a single species remains: O. oeni. During ageing, Pediococcus damnosus can also develop.
Despite their relative specificity, lactic acid bacteria broadly cause more or less significant organoleptic changes. Theses changes may include beneficial activities such as malolactic fermentation but they may also be harmful (ropy wines, biogenic amine production, excess of volatile acidity, etc.). It is therefore necessary to identify and count the populations involved. Various analytical tools are available for this purpose.
Méthod |
Culture on selective medium |
Epifluorescence microscopy
| Real time PCR |
---|---|---|---|
Results |
Population of cultivable lactic acid bacteria : CFU*/mL
|
Population of viable bacteria in cellules/mL | Population of lactic acid bacteria in equivalent CFU*/mL |
Volume | 125 mL | 125 mL | 125 mL |
Analysis duration | 12 days | 1 day | days |
* CFU = Colony Forming Unit
Méthode | Real time PCR | PCR on wine / colonie |
---|---|---|
Results | Population of lactic acid bacteria producing biogenic amines in equivalent CFU*/mL | Presence / absence of lactic acid bacteria with ropy character (ropy wines) |
Volume | 125 mL | 125 mL / Petri dish |
Analysis duration |
2 days | 12 days/ 2 days |
* CFU = Colony Forming Unit
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- Genetic test with reference strains