Suivi de la dégradation d’une huile de table lors de friture par spectroscopie infrarouge

Abstract

This study has a main objective which is to develop and explore the potential of the infrared spectral method as a quick approach to evaluate the quality of oil during heating. FTIR spectroscopy has shown the effect of heat treatment on the quality of vegetable oils as a function of time and temperature of heating on the following points: A decrease in the lengths of the carbon chains in the oils during heating. This phenomenon is at the origin of the decrease of the absorbance intensities of vibration bands of symmetrical elongation (2854 𝑐𝑚−1 ) and asymmetrical (2924 𝑐𝑚−1) and of the band of deformation of group CH2 towards 724 𝑐𝑚−1 ; an increase in the rate of esterification (visible at the C = O and C-O groups), which is indicative of an increase in the degree of oxidation of the oil and finally an increase in the amount of "trans" isomer (strain band of the group = C-H at about 972 𝑐𝑚−1 ), which occurs at the same time as the decrease in the amount of the "cis" isomer (the stretching vibration band of the group = C-H at 3012 𝑐𝑚−1 ).