Assessment of conventional and microwave heating induced degradation of carotenoids in olive oil by VIS Raman spectroscopy and classical methods

Raman spectroscopy, as a fast non-destructive method, has shown its potential in revealing heat-induced degradation of extra virgin olive oil carotenoids during microwave versus conventional heating processes. A progressive degradation in carotenoids was observed, starting at 180 °C and 140 °C in microwave and conventional heating processes respectively; this was followed by a rapid degradation at 180 °C only with conventional heating. As the main difference, the Raman bands due to carotenoids completely disappeared at 203 °C with conventional heating, while these bands could still be observed even up to 225 °C with microwave heating. Furthermore a loss of cis double bonds and slightly changes in free fatty acid was also observed in both heating processes. A precise calibration model was established using partial least squares regression, which can be used for monitoring carotenoids content degradation during heating. The accuracy of the model was estimated using the root mean square errors and the correlation coefficient.