PHENOLICS IN WHITE FREE RUN JUICES AND WINES FROM PENEDES BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY - CHANGES DURING VINIFICATION

A precise and sensitive HPLC method, with diode array detection, for p henolic compounds in white juices and wines is presented. Eighteen of these phenolics have been identified and quantitated in white free run juices and 19 in white wines. Identification of benzoic acids was con firmed by GC/MS. The only flavonol detected, quercetin 3-glucuronide, was identified by TLC and electrospray (ESI) techniques. Levels of the trans- and cis-hydroxycinnamic acids, flavonoids, and benzoic acids p resent in white juice and wine are reported. Hydroxycinnamates were th e major phenols; among them, trans-caftaric, trans-coutaric, and cis-c outaric were the predominant. The cis-coutaric represented a substanti al percentage in the total amount of phenols. Flavonoids were present at low concentration, and benzoic acids were the minor compounds. Duri ng white vinification, a significant decrease in the phenolic compound s present in free run juice was observed, mainly caused by the hydroxy cinnamic acids.