REVERSED-PHASE HPLC FOLLOWING THIOLYSIS FOR QUANTITATIVE ESTIMATION AND CHARACTERIZATION OF THE 4 MAIN CLASSES OF PHENOLIC-COMPOUNDS IN DIFFERENT TISSUE ZONES OF A FRENCH CIDER APPLE VARIETY (MALUS-DOMESTICA VAR. KERMERRIEN)

Phenolic compounds, which are present in the epidermis zone, parenchym a zone, core zone, and seeds of fruit (Malus domestica var. Kermerrien ), were extracted from freeze-dried material by three successive solve nt extractions. The dry methanol extract and the dry aqueous acetone e xtracts were analyzed using reversed-phase HPLC coupled with diode arr ay detection following thiolysis to quantify phenolic compounds accord ing to their classes (hydroxycinnamic acid derivatives, flavan-3-ols, flavonols, and dihydrochalcones). The method is suitable for the deter mination of the relative proportions of the different classes of polyp henols and provided information on the constitutive units and the aver age degree of polymerization of oligomeric and polymeric procyanidin s tructures. Results showed that procyanidins are the predominant phenol ic constituents in cider apple fruits, much of them corresponding to h ighly polymerized structures.