Phenolic compounds in cork used for production of wine stoppers as affected by storage and boiling of cork slabs

Phenolic compounds (benzoic and cinnamic acid derivatives, vanillin,syringaldehyde and acetovanillone) were identified in cork used forproduction of wine stoppers by extraction in an ethanolic solution andby HPLC analysis. The effect of storage and boiling of cork slabs onthese compounds were investigated. In each sample, cinnamic acids andvanillin have predominated among phenolics. Boiled cork wassignificantly different from raw slabs in the concentration ofprotocatechuic, caffeic, p-coumaric acids, and vanillin. The significantdifferences between cork from stored and from unstored slabs wereevident in protocatechuic, 4-hydroxybenzoic, caffeic, and ferulic acids.Storage of slabs increased the amount of extractable cinnamic acids. Onthe other hand, boiling decreased the concentration of the same phenolicacids and increased that of vanillin. Boiling after storage can bebeneficial to the cork quality, reducing the amount of potentiallynegative flavor compounds (cinnamic acids) and increasing potentiallypositive flavor compounds (vanillin).