Raman and Fluorescence spectroscopic techniques have been employed for studying the temperature effects on the molecular composition of extra virgin olive oil (EVOO). In addition, both techniques have also been employed for the characterization of Desi Ghee (liquefied butter) obtained from Buffalo milk along with the effects of temperature on its molecular composition. Raman spectra of EVOO samples has been obtained at excitation wavelength of 785 nm. Intensity ratio of Raman bands at 1267 cm-1 and 1302 cm-1 have been used to determine the loss of unsaturation in heated EVOO samples as compared to nonheated ones. Similarly, Fluorescence emission bands at 380, 440, 455 and 525 nm are labelled for vitamin E, band at 673 nm is assigned to chlorophyll, band at 525 nm is assigned to beta carotene. As a result of heating, emission bands at 525 nm got affected most revealing deterioration of beta carotene and vitamin E. The ratio between the sum of intensities of fluorescence bands at 380, 440, 470, 525 nm to 673 nm from heated and non-heated EVOO samples has been used to determine the deterioration of beta carotene and vitamin E contents. Results of both Raman and Fluorescence spectroscopic analysis have suggested a temperature range from 140 to 150 oC reasonably safe for cooking/frying of food with EVOO. In addition, EVOO can be heated for longer period of time up to 30 minutes but with the passage of time it deteriorates. However, in pressure cooker EVOO can be used for comparatively longer times up to 60 minutes. It has also been found that one time use of EVOO is better for cooking within defined temperature range and its reuse may be avoided. In conclusion, EVOO can be safely used for frying/cooking in the defined cooking range with proper management of heat source. Moreover, for the classification of heated and non-heated EVOO samples, principle component analysis (PCA) has been employed which differentiate the samples on the basis of their spectral differences. Similarly, Raman spectra at 785 nm depicted molecular composition of DG with prominent Raman bands around 1125 and 1440 cm-1 labelled for saturated fatty acids, 1258, 1270 and 1300 cm-1 assigned to unsaturation, 1525 cm-1 represents beta carotene and 1655 cm-1 is labelled for isomers of conjugated linoleic acid (CLA). The variations in the intensity ratio of Raman bands at 1258/1270 cm-1 indicates the loss of unsaturation and at 1440 cm-1 and 1650 cm-1 exhibit degradation of valuable lipids and CLA contents as a result of heating. In addition, Fluorescence spectra of ghee samples obtained at excitation wavelength of 280 and 410 nm showed that DG is enriched with CLA, vitamin-A and small quantities of vitamin D, E and K. Further, heating analysis has revealed that Ghee remains stable around a temperature range of 140-150 oC when heated for a time period of 30 minutes. Principal component analysis (PCA) has been used for the classification of overlapping spectral data which was difficult to differentiate visually. Results of both Raman and Fluorescence spectroscopy have suggested a temperature-range from 140 to 180 oC considered safe for household cooking/frying purposes using DG. Conclusively, it is found that both EVOO and DG show negligible deterioration of their natural molecular composition when heated at temperature range from 140-150 oC. Therefore, this temperature range sounds good for cooking/frying with EVOO and DG. Moreover, both EVOO and DG start getting oxidized more at temperatures from 180-200 oC with the evolution of secondary oxidation products and become rancid at 250 oC.
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