Evolution of benzoate derivatives and their hydroxycinnamate analogues during ageing of white wines in oak barrels

Two white wines produced industrially, originating from the V. vinifera cultivars Asyrtiko and Chardonnay, were monitored with regard to the evolution of selected phenolic acids, during “on lees” ageing in oak casks for a period of 197 days. Four benzoic acid derivatives, namely p-hydroxybenzoic acid, protocatechuic acid, vanillic acid and syringic acid, and their corresponding hydroxycinnamate analogues p-coumaric acid, caffeic acid, ferulic acid and sinapic acid, were considered. The most abundant benzoate and hydroxycinnamate derivatives were protocatechuic acid and caffeic acid, with concentrations varying from 0.31 to 0.42 μg mL−1 and 1.71 to 2.47 μg mL−1, respectively, while the profile of both phenolic categories was essentially the same in both wines. The evolution pattern of benzoates showed that maximum concentration of protocatechuic acid was achieved after approximately 100 days (0.45–0.48 μg mL−1) of ageing for both samples, whereas all other compounds exhibited an increasing trend towards the end of the examination period. The concentration of all hydroxycinnamates increased at the end of ageing, from 49.4% (caffeic acid) to 123% (p-coumaric acid), to the exception of sinapic acid which underwent practically no changes.