ANALYSES OF PHENOLIC AND FURFURAL COMPOUNDS IN CONCENTRATED AND NON-CONCENTRATED APPLE JUICES

A high-performance liquid chromatography (HPLC) analytical method, using a combination of ultraviolet-diode array (UV) and electrochemical (EC) detectors, was developed for the characterization and quantification of phenolic and furfural compounds in apple juice. The limits of detection of phenolic compounds with EC detection were 4-500 times greater than those obtained with UV detection. The HPLC method allowed the identification and quantification of the major (chlorogenic and coumaroylquinic acids and phloridzin) and minor (caffeic, p-coumaric, ferulic, gallic and protocatechuic acids, and catechin) phenolic compounds, as well as 5-hydroxymethyl-2-furaldehyde and 2-furaldehyde in apple juice. The total phenolic content in apple juices of various origins varied from 28.85 to 115.49 mg/l. The concentrations of phenolic and furfural compounds varied widely among the non-concentrated and concentrated apple juices.