Assessing the extent of oxidation in thermally stressed vegetable oils. Part I: Optical characterization by photothermal and some conventional physical methods

UV absorption, hyphenated HPLC-dual beam thermal lens,spectrometry, photoluminescence, optothermal window (OW) method at the NIR wavelengths (using xenon lamp and optoparametric oscillator (OPO) as the excitation sources), FTIR and Raman spectroscopies, refractometry, dielectric spectroscopy and a widely adopted Rancimeter approach were studied in terms of the potential of each procedure to assess the extent of changes induced in safflower oil subjected to accelerated oxidation under well controlled conditions (ten hours long at 130 degrees C and presence of air flow 300 ml/min). Thus obtained "analytical indices" for optical characterization of thermally stressed oil, were then compared in terms of mean value and variance); the correlation coefficients for all analytical indices were also determined.