Effects of pH and ferric ions on the antioxidant activity of olive polyphenols in oil-in-water emulsions

• Type: Article in International Scientific Journal
• Date: 2002

Authors

Paiva Martins, F (Author) FCUP; Gordon, MH (Author) Other

Journal

Title: Journal of the American Oil Chemists' Society

Vol. 79

Pages: 571-576

ISSN: 0003-021X

Indexing

ISI Web of Knowledge - 58 Citations

Scopus - 66 Citations

Scientific classification

FOS: Agrarian Sciences > Other Agrarian Sciences

Other information

Authenticus ID: P-000-P7P

DOI: 10.1007/s11746-002-0524-4

Abstract (EN): The effects of four phenolic compounds occurring in olives and virgin olive oil, namely, oleuropein, hydroxytyrosol, 3,4-dihydroxyphenylethanol-elenolic acid (3,4-DHPEA-EA) and 3,4-dihydroxyphenylethanol-elenolic acid dialdehyde (3,4-DHPEA-EDA), on the oxidative stability of stripped olive oil-in-water emulsions were studied at three pH values in the presence or absence of ferric chloride at 60degreesC. In the stability test, the addition of phenolic compounds in emulsions at pH 5.5 significantly extended the induction time of lipid oxidation, and the activities in decreasing order were 3,4-DHPEA-EA > 3,4-DHPEA-EDA > hydroxytyrosol > alpha-tocopherol similar to oleuropein >> control. The effect of concentration, iron, and pH on the antioxidant activity of the phenolic compounds in stripped olive oil-in-water emulsions was analyzed by response surface methodology. Oleuropein and hydroxytyrosol enhanced the prooxidant effect of ferric chloride at pH 3.5 and pH 5.5 but not at pH 7.4. The 3,4-DHPEA-EDA reduced the prooxidant effect of ferric chloride at pH 5.5 and pH 7.4, but at pH 3.5 prooxidant effects were evident at higher phenol concentration. The 3,4-DHPEA-EA reduced the prooxidant effect of ferric ions at all pH values tested. Differences in activity of the phenols may be explained by consideration of their free radical scavenging activity and ferric reducing capacity.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 6