The same behaviour was registered for the oleuropein derivatives contained in ROPE(4) (Fig. 2C) where, in fact, the amount expressed as the sum of 3,4-DHPEA and 3,4-DHPEA-EDA decreased by 88.3% during the twelve hours of heating: after an initial increase in the concentration of 3,4-DHPEA, after four hours of experimentation it decreased, whereas the simultaneous accumulation of the oxidised dialdehydic form of decarboxymethyl elenolic acid began and continued to increase throughout the entire heat treatment (Fig. 2D). Furthermore, the concentration of 3,4-DHPEAEDA decreased with the progress of the thermal oxidation reaction,and after the initial increase of oxidised 3,4-DHPEA-EDA, this began to fall after six hours (Fig. 2D).