Effect of wood on the phenolic profile and sensory properties of wine vinegars during ageing

Abstract

A crucial step in the production of high-quality wine vinegars is ageing in wood. This study aims to determine how wood barrels affect vinegar quality. For this purpose, vinegars were aged in barrels made from acacia, cherry, chestnut and oak wood. Two kinds of vinegars were studied: balsamic and red-wine vinegars. Analysis of samples included total phenol index (TPI), total monomeric anthocyanins (TA), dry extract, and phenolic and furanic compounds by liquid chromatography with photodiode array detection (LC–DAD) in a total of 98 samples. The concentration of HMF, 2-furfuraldehyde, protocatechualdehyde and vanillin significantly increased during ageing. Taxifolin is present in vinegars aged in cherry wood, confirmed by liquid chromatography–mass spectrometry/mass (LC–MS/MS). Hence, it can be a marker of vinegars aged in cherry wood. This is the first time that this compound has been identified in wine vinegars. On the other hand, ellagic acid is a characteristic compound for samples aged in chestnut and oak barrels. An unknown peak was found in all vinegar samples (groups F, T and M) which were aged in acacia wood. Linear discriminant analysis was used to classify samples as a function of the type of wood and ageing time, with phenolic compounds as variables. The linear functions obtained correctly classified – at 100% – red vinegars according to the type of wood. If ageing time (0–365 days) is considered, 62.5% and 100% of the red and balsamic vinegar samples, respectively, were well classified. The effect of wood on vinegar quality is obvious enough to be perceived by the senses in triangle tests. Woody, sweet and vanilla descriptors presented the highest scores for vinegars aged in oak wood. On the other hand, ageing in cherry wood increased markers for red-fruit attributes. These results prove that wood used in vinegar ageing determines both the chemical composition and sensorial properties.