Differentiation by Phenolic Profile of Apple Juices Prepared According to Two Membrane Techniques

Crossflow filtration techniques (micro- and ultrafiltration), using inorganic membranes, were employed to clarify apple juice. Changes in the polyphenol composition (procyanidins, hydroxycinnamic derivatives, and dihydrochalcones) were monitored throughout the clarification process by means of a simple and reliable HPLC procedure. A factorial repeated 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 hydroxycinnamic derivative) were influenced by membrane type, and (−)-epicatechin and phloridzin were influenced by process time. Appearance terms were also closely related with the factors studied. Ultrafiltration at low temperature produced an apple juice with an adequate level of stability. Analysis of polyphenols, together with the use of exploratory data analysis (clustering techniques), factor analysis (PCA), classification (LDA and KNN), and modeling techniques (SIMCA and PLS), allowed the authors to differentiate apple juices clarified by means of crossflow membrane technology.