Contribution to the knowledge of malolactic fermentation influence on wine aroma.

In this work, we study two aspects of malolactic fermentation: the use of industrial lactic acid bacteria starter-cultures in a white Sauvignon wine and the effects of the bacterial activity on the composition of wines in terms of volatile substances from oakwood during partial malolactic fermentation in barrels. A sensory evaluation was made by the use of discriminative and descriptive methods. The consequences of bacterial development are thus limited, but it is nevertheless possible to make characteristic observations. The carbonyl substances were formed in connection with a more or less fast bacterial growth and a degradation of the citric acid. However, the influence of the bacterial starter-culture is difficult to establish. The concentration of the compounds resulting from wood was higher in the wines after malolactic fermentation compared to a wine not having undergone bacterial development. Greater complexity was perceived during the sensory analysis, with buttered, spiced, roasted, vanilla, and smoked notes. On the other hand, the intensity of the descriptors characteristic of grape variety decreased.