In European Union, the Commission Regulation 432/2012 introduced the possibility to report the health claim “Olive oil polyphenols contribute to the protection of blood lipids from oxidative stress” if the olive oil contains at least 5 mg of hydroxytyrosol (HTyr) and its derivatives (e.g. oleuropein complex and tyrosol (Tyr) per 20 g of product). The purpose of this work was to find a simple and suitable method −among the most widely employed− to guarantee the proper determination and quantification of the olive oil phenolic content. Thus several protocols were employed: total phenolics by Folin-Ciocalteu (FC) spectrophotometric method and o-diphenolics by the colorimetric molibdate method (MbM) versus phenols by high-performance liquid chromatography-diode array detection (HPLC-DAD), all performed before and after an acid hydrolysis of the phenolic complex forms of the oil polar fraction. Having regard acid hydrolysis-HPLC-DAD the most sensitive and specific method for evaluating the phenolic content. Also different compounds were used to construct the calibration curves: tyrosol, hydroxytyrosol, oleuropein, gallic acid and caffeic acid. The concentrations obtained of 10 oil samples with very different phenolic profiles were statistically compared by means of two-tailed paired t-tests. In this way, results obtained by FC assay before and after acid hydrolysis -quantifying with gallic acid- were statistically comparable with acid hydrolysis-HPLC-DAD -quantifying with external calibration curves of HTyr and Tyr-.

Searching a suitable method to determine the phenolic content of virgin olive oils in order to bear the health claim introduced by Commission Regulation (EU) 432/2012

VALLI, ENRICO;BENDINI, ALESSANDRA;GALLINA TOSCHI, TULLIA;
2014

Abstract

In European Union, the Commission Regulation 432/2012 introduced the possibility to report the health claim “Olive oil polyphenols contribute to the protection of blood lipids from oxidative stress” if the olive oil contains at least 5 mg of hydroxytyrosol (HTyr) and its derivatives (e.g. oleuropein complex and tyrosol (Tyr) per 20 g of product). The purpose of this work was to find a simple and suitable method −among the most widely employed− to guarantee the proper determination and quantification of the olive oil phenolic content. Thus several protocols were employed: total phenolics by Folin-Ciocalteu (FC) spectrophotometric method and o-diphenolics by the colorimetric molibdate method (MbM) versus phenols by high-performance liquid chromatography-diode array detection (HPLC-DAD), all performed before and after an acid hydrolysis of the phenolic complex forms of the oil polar fraction. Having regard acid hydrolysis-HPLC-DAD the most sensitive and specific method for evaluating the phenolic content. Also different compounds were used to construct the calibration curves: tyrosol, hydroxytyrosol, oleuropein, gallic acid and caffeic acid. The concentrations obtained of 10 oil samples with very different phenolic profiles were statistically compared by means of two-tailed paired t-tests. In this way, results obtained by FC assay before and after acid hydrolysis -quantifying with gallic acid- were statistically comparable with acid hydrolysis-HPLC-DAD -quantifying with external calibration curves of HTyr and Tyr-.
2014
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Reboredo-Rodríguez P.; Valli E.; Bendini A.; Gallina Toschi T.; Simal-Gándara J. a
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/362716
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