Effect of pH on malolactic fermentation in southern Italian wines

This study investigated the influence of pH on malolactic fermentation (MLF) in white wines (adjusted to pH 3.2, 3.4 and 3.8, respectively) from Falanghina grapes and red wines (adjusted to pH 3.4 and 3.8, respectively) from Tintilia grapes. The wines were inoculated with Oenococcus oeni and Lactobacillus plantarum strains, and a mix of them (50:50), in red Tintilia only. The time required to complete MLF in wines from white Falanghina grapes at pH 3.4 and 3.8 was lower with O. oeni, while MLF did not occur at pH 3.2. In red Tintilia, MLF was always completed within 35 days; at high pH (3.8) a significant increase in histamine was detected, while the decrease in citric acid concentration caused an increase in volatile acidity. Sensorial analysis showed an enhancement of red berry and spicy notes in red Tintilia at pH 3.8. PCA on white Falanghina showed that wines at pH 3.2 were located on the negative side of PC1 with higher scores for dry vegetable, sulphide, violet and toasted attributes. Wines at pH 3.4 and 3.8 were located on the positive side of the PC1 with butter and apple attributes. L. plantarum enhanced floral notes in white Falanghina wines and showed a good organoleptic impact on red Tintilia wines, which sensorial intensity was improved by a commercial mix (50:50) of O. oeni and L. plantarum.