The main goal of this study was to assess the effectiveness of FTIR spectroscopy to detect the changes occurred in quality of olive oil (OO), sunflower oil (SFO) and their mixture as effect of convective heating for 8 and 16 h under frying procedures. The IR bands changing during heating in oil samples have been examined. It can be claimed that a band shift noticed at 3011 cm-1 assigned to the C-H stretching vibration of the cis-double bond allows estimating both OO adulteration by SFO addition as well as the extent of oxidative degradation occurred in oils as a result of heating at high temperature. The changes reported in the spectral domains 2800-3050 cm-1, 1600-1800 cm-1 as well as 700-1200 cm-1 after heating at elevated temperature aid to the monitoring of oxidation process. Based on calibration curves absorbance at some wave numbers (the most relevant seem to be 3011, 3006 and 912 cm-1) versus percent of SFO added in OO it is possible to determine the degree of OO adulteration. A significant positive correlation (R>0.95) were found for untreated oil samples. In addition, these curves could be useful to estimate the extent of oxidative alteration that occurred in oils as effect of heating. The main drawback is the fact that with extend of heating time the linearity of these curves decreased. After 16 hours of thermal treatment these curves are not useful to assess the degree of OO adulteration by SFO addition. Data achieved by carrying out of this study highlighted that FTIR spectroscopy showed a high potential to be a useful method for monitoring the process of oxidative degradation occurred in edible oils subjected to heating at high temperature.
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