Fluorescence spectroscopy for monitoring deterioration of extra virgin olive oil during heating.
The potential of fluorescence spectroscopy for characterizing the deterioration of extra virgin olive oil (EVOO) during heating was investigated. Two commercial EVOO were analysed by HPLC to determine changes in EVOO vitamin E and polyphenols as a result of heating at 170 degrees C for 3 h. This thermal oxidation of EVOO caused an exponential decrease in hydroxytyrosol and vitamin E (R(2)=0.90 and 0.93, respectively) whereas the tyrosol content was relatively stable. At the same time, amounts of preformed hydroperoxides (ROOH), analysed by an indirect colorimetric method, decreased exponentially during the heating process (R(2)=0.94), as a result of their degradation into secondary peroxidation products. Fluorescence excitation spectra with emission at 330 and 450 nm were recorded to monitor polyphenols and vitamin E evolution and ROOH degradation, respectively. Partial least-squares calibration models were built to predict these indicators of EVOO quality from oil fluorescence spectra. A global approach was then proposed to monitor the heat charge from the overall fluorescence fingerprint. Different data pretreatment methods were tested. This study indicates that fluorescence spectroscopy is a promising, rapid, and cost-effective approach for evaluating the quality of heat-treated EVOO, and is an alternative to time-consuming conventional analyses. In future work, calibration models will be developed using a wide range of EVOO samples.
Laboratoire de chimie analytique, Institut National Agronomique Paris-Grignon, INRA UMR Ingénierie Analytique pour la Qualité des Aliments (IAQA), 16 rue Claude Bernard, 75005 Paris cedex 05, France. cheikhou@inapg.inra.fr
Rana
R
Cheikhousman
Manuela
M
Zude
Delphine Jouan-Rimbaud
DJ
Bouveresse
Claude L
CL
Léger
Douglas N
DN
Rutledge
Inés
I
Birlouez-Aragon
D006358:Hot Temperature; D008054:Lipid Peroxides / Q000032:analysis; D000069463:Olive Oil; D010626:Phenylethyl Alcohol / Q000031:analogs & derivatives / Q000032:analysis; D010938:Plant Oils / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*; D014810:Vitamin E / Q000032:analysis
D008054:Lipid Peroxides; D000069463:Olive Oil; D010938:Plant Oils; D014810:Vitamin E; C011867:4-hydroxyphenylethanol; D010626:Phenylethyl Alcohol