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-.
Reboredo-Rodríguez P., Valli E., Bendini A., Gallina Toschi T., Simal-Gándara J. a (2014). 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.
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-.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
