Inhibitory activity of phenolic compounds against microorganisms involved in oenological fermentations

Stuck fermentations often occur in musts derived from high quality and high phenolic content grapes, which, even in the most favorable nutritional conditions, are unable to normally develop the fermentative processes. The aim of this work was to evaluate the antimicrobial activity of wine and grape phenolic extracts versus oenologic yeast and lactic bacteria strains.

The use of a phenolic-subtractive oenological product which would minimize the stuck fermentations has also been studied. This product would reduce the contents of the phenolic compounds with the highest microbial development inhibitory activity, without causing a negative impact on the organoleptic quality of the wine.

For this purpose, the inhibitory development activity has been evaluated, by using viable cell counting procedures, after the incubation of the microorganisms in the presence of phenolic extracts from grape skins or in the presence of phenolic extracts obtained from monovarietal wines treated with the phenolic-subtractive product.

Results obtained showed that the phenolic extracts exhibited different inhibitory activity of the microbiological development and that the flavonol and anthocyanin content could be the main responsible of this activity.

Extracts from wines treated with a product that reduces the content of these compounds provoked higher microbiological development. Likewise, assays performed using skin extracts mainly containing flavonols and anthocyanins showed important inhibitory activity.