Background and Aims: This study investigated the interactive effects of malolactic bacterial strain, pre-malolactic fermentation (MLF) pH value and wine matrix/style on modulating chemical and sensory impacts of MLF in Cabernet Sauvignon wine.
Methods and Results: Malolactic fermentation was conducted in two styles of Cabernet Sauvignon wine, a lighter, fruity style and a more complex style. Each wine was divided into two equal volumes, one was adjusted to pH 3.3 the other to pH 3.7. Each of these wines was further divided into four equal volumes, three of which were inoculated with three different commercial Oenococcus oeni strains and the fourth used as a non-MLF control. Following MLF, all wines were standardised to approximately pH 3.5. The MLF treatments exhibited significant strain- and wine matrix-dependent effects on a diversity of chemical components, including esters, volatile acids and higher alcohols, and on colour. Descriptive sensory analysis also demonstrated significant effects on several sensory properties. Partial least squares analysis revealed a strong correlation between important chemical components and sensory attributes, including overall fruit flavour and dark fruit aroma.
Conclusions: The extent and diversity of the impacts of MLF on wine chemical and sensory properties were directly influenced by choice of bacterial strain, pre-MLF pH and wine matrix composition. Relatively harsh conditions (pH 3.3, 14.8% alcohol) protracted the time of MLF and supported greater differences between Oenococcus oeni strains in their modulation of important wine chemical components.
Significance of the Study: This study increases knowledge of the significant impacts of MLF on wine chemical composition and associated sensory properties. Specifically, variations in the effect of MLF on wine sensory and chemical properties has been found to arise from the choice of bacterial strain and wine matrix composition/style.