DIFFERENTIATION BY PHENOLIC PROFILE OF APPLE JUICES PREPARED ACCORDING TO 2 MEMBRANE TECHNIQUES

Crossflow filtration techniques (micro- and ultrafiltration), using in organic membranes, were employed to clarify apple juice. Changes in th e polyphenol composition (procyanidins, hydroxycinnamic derivatives, a nd dihydrochalcones) were monitored throughout the clarification proce ss by means of a simple and reliable HPLC procedure. A factorial repea ted measures design was constructed to ascertain the influence of the factors (membrane type, temperature and process time) on the levels of phenolic compounds. Procyanidin B1 and an unknown peak (probably a hy droxycinnamic derivative) were influenced by membrane type, and (-)-ep icatechin and phloridzin were influenced by process time. Appearance t erms were also closely related with the factors studied. Ultrafiltrati on at low temperature produced an apple juice with an adequate level o f stability. Analysis of polyphenols, together with the use of explora tory data analysis (clustering techniques), factor analysis (PCA), cla ssification (LDA and KNN), and modeling techniques (SIMCA and PLS), al lowed the authors to differentiate apple juices clarified by means of crossflow membrane technology.