The antioxidant activity of the phenolic fraction of extra virgin olive oil was assessed in samples that had a decreasing content of antioxidants in the presence and absence of copper ions as a catalyst of autoxidation. The oxidation process was evaluated by measuring primary and secondary oxidation products. Changes in phenols and tocopherols were investigated by high-performance liquid chromatography. Both the total phenol content and their antioxidant activity were monitored by spectrophotometric assays (with Folin-Ciocalteu and ABTS radical positive reagents). The important role of phenolic compounds (particularly the o-diphenols) in protection from autoxidation was confirmed. However, the tocopherols were more quickly consumed in oils that had the lowest content of o-diphenols, which also showed evidence of an ability to chelate copper. In particular, a dramatic decrease was observed in the isomeric form of decarboxymethyl-oleuropein aglycone after addition of the metal, despite its significant increase in samples stored in the absence of copper.
A. Bendini, L. Cerretani, S. Vecchi, A. Carrasco-Pancorbo, G. Lercker (2006). Protective Effects of Extra Virgin Olive Oil Phenolics on Oxidative Stability in the Presence or Absence of Copper Ions. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY, 54, 4880-4887 [10.1021/jf060481r].
Protective Effects of Extra Virgin Olive Oil Phenolics on Oxidative Stability in the Presence or Absence of Copper Ions
BENDINI, ALESSANDRA;CERRETANI, LORENZO;LERCKER, GIOVANNI
2006
Abstract
The antioxidant activity of the phenolic fraction of extra virgin olive oil was assessed in samples that had a decreasing content of antioxidants in the presence and absence of copper ions as a catalyst of autoxidation. The oxidation process was evaluated by measuring primary and secondary oxidation products. Changes in phenols and tocopherols were investigated by high-performance liquid chromatography. Both the total phenol content and their antioxidant activity were monitored by spectrophotometric assays (with Folin-Ciocalteu and ABTS radical positive reagents). The important role of phenolic compounds (particularly the o-diphenols) in protection from autoxidation was confirmed. However, the tocopherols were more quickly consumed in oils that had the lowest content of o-diphenols, which also showed evidence of an ability to chelate copper. In particular, a dramatic decrease was observed in the isomeric form of decarboxymethyl-oleuropein aglycone after addition of the metal, despite its significant increase in samples stored in the absence of copper.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
