HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY OF THE NEUTRAL PHENOLIC-COMPOUNDS OF LOW-MOLECULAR-WEIGHT IN APPLE JUICE

The neutral phenolic compounds, (+)-catechin, (-)-epicatechin, flavan- 3-ols polymers (procyanidins), phloridzin, phloretin xyloglucoside, an d the flavonol glycosides (isoquercitrin, hyperin, quercitrin, avicula rin, and rutin), in apple juice were extracted with ethyl acetate and separated and quantified by reversed-phase HPLC on a Cia column using an acidified water (pH 2.8)-methanol solvent gradient. A diode array d etector was used to evaluate the separation and to identify the phenol ic compounds. The recovery obtained for the flavanols and some dihydro chalcones ranged between 93% and 106%. On the contrary, the 30% recove ry rate obtained for flavonols shows that ethyl acetate Liquid-liquid extraction, usually employed in this type of study, is not recommended for the extraction of these last compounds.