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

A high-performance liquid chromatography (HPLC) analytical method, usi ng a combination of ultraviolet-diode array (UV) and electrochemical ( EC) detectors, was developed for the characterization and quantificati on of phenolic and furfural compounds in apple juice. The limits of de tection of phenolic compounds with EC detection were 4-500 times great er than those obtained with UV detection. The HPLC method allowed the identification and quantification of the major (chlorogenic and coumar oylquinic acids and phloridzin) and minor (caffeic, p-coumaric, feruli c, gallic and protocatechuic acids, and catechin) phenolic compounds, as well as 5-hydroxymethyl-2-furaldehyde and 2-furaldehyde in apple ju ice. The total phenolic content in apple juices of various origins var ied from 28.85 to 115.49 mg/l. The concentrations of phenolic and furf ural compounds varied widely among the non-concentrated and concentrat ed apple juices.