Changes in phenolic composition of apple juices by HPLC with direct injection

An analytical procedure for the quantitative determination of the major polyphenols in apple juices which successfully employs a RP-HPLC system without prior treatment of the sample is described. Apple juices were clarified by microfiltration and ultrafiltration without previous treatment. Polyphenols monitored were influenced by clarification technology employed for stabilising the apple juices. The p-coumaric acid derivative was significantly affected by membrane type and filtration time, while (- )-epicatechin and phloridzin were influenced by filtration time.