Effects of malolactic fermentation on colour stability and phenolic composition of Petit Verdot red wines

In the present work we evaluate the effects of malolactic fermentation (MLF) on the colour parameters and polyphenolic composition of Petit Verdot red wines. MLF caused a significant decrease in colour intensity in wines, approximately 9%. In line with that, the results showed a decrease in the concentration of anthocyanins (acylated and non-acylated), but an increase of the pyranothocyannins concentration. MLF did not produce important variations on the content of hydroxycinnamic acids derivatives, stilbenes and flavonols. Regarding flavan-3-ols, MLF caused a decrease in monomers, total flavan-3-ols and percentage of galloylation, and an increase on the percentage of prodelphinidins. However, no effect over mean degree of polymerisation was observed. Thus, it is unlikely that these changes may affect the acceptability of wines by consumers.