Identification and quantification of the major phenolic compounds occurring in the main solid wastes and by-products of the extra virgin olive oil production chain

After the processing of olives for the extra virgin olive oil extraction, less than 1-2% of the phenolic compounds (PCs) are found in EVOO, whereas the majority of them are lost either in the pomace or in the olive mill waste water (OMWW). Significant content of bioactive PCs are also occurring in the olive leaves, which form a huge bulk of solid wastes produced by the cultivation of these trees. Thus, both the olive processing industry and the cultivation of olive trees are responsible for the production of large quantities of by-products, which might be considered either an environmental problems or a source of novel bioactive ingredients that could be used in the pharmaceutical, nutraceutical and cosmetic industry. This communication reports the results a study carried out to investigate a variety of factors that influence the separation, identification and quantification of bioactive PCs occurring in olive leaves, EVOO and OMWW. Several extraction methods have been evaluated on their efficiency in recovering individual PCs, whose occurrence and abundance have been determined by reversed phase high performance liquid chromatography (RP-HPLC), using both diode array detector (DAD) and the hyphenation with mass spectrometry by an electrospray ionization source (ESI-MS). The RP-HPLC methods employed in the study have been developed by a Design of Experiments (DoE) approach, which has allowed the simultaneous optimization of pH and composition of the hydro-organic mobile phase, shape and duration of the binary gradient elution program, and column temperature, on the basis of the results of a limited number of experiments. Research financed by the EU Project grant No 734899