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A study of the precursors of the natural antioxidant phenol 3,4-dihydroxyphenylglycol in olive oil waste

Lama-Muñoz, Antonio, Rodríguez-Gutiérrez, Guillermo, Rubio-Senent, Fátima, Palacios-Díaz, Rafael, Fernández-Bolaños, Juan
Food chemistry 2013 v.140 no.1-2 pp. 154-160
antioxidants, detectors, fractionation, heat treatment, high performance liquid chromatography, ionization, mass spectrometry, olive oil, phenol, solid wastes, solubilization, verbascoside, waste treatment
3,4-Dihydroxyphenylglycol (DHPG) is a potent antioxidant recently found in the free form in olive oil and table olives. DHPG can be recovered from olive oil solid waste by a hydrothermal treatment. It was observed that an increase in the concentration of DHPG occurred when alperujo aqueous extracts were subjected to mild thermal conditions (post-treatment). This fact indicates that certain solubilized compounds or precursors containing DHPG which is released with the post-treatment. In the present study, the precursors of DHPG were identified and characterized after extraction from alperujo using thermal treatment and purification by fractionation on Amberlite® XAD16 polyamide and semi-preparative reverse-phase HPLC columns. Their structures were elucidated using HPLC coupled to diode array detector (DAD) and electrospray ionization mass spectrometry (ESI-MS). The results identified three compounds as precursors, and their structures can be attributed to the diastereoisomeric forms of the two β-hydroxy derivatives of verbascoside and isoverbascoside (β-hydroxyacteoside and β-hydroxyisoacteoside), and 2″-hydroxyoleuropein, all of which contain a DHPG moiety, potentially explaining the increases in the concentration of this phenolic compound in olive oil waste.