Identification of olive oil counterfeit by the means of infrared absorption and raman scattering spectroscopy

Edible oils are very important component for human diet. However, a lot of adulterated oils are being detected worldwide and this is becoming a problem. In this work methods of infrared absorbtion and Raman scattering were used to see if those methods are good for determing the quality of edible oils. For infrared absorbtion attenuated total reflection (ATR) method was used to register spectra of 23 different edible oils and Raman scattering method was used to register spectra of 45 different edible oils. All data was analysed in 3 different methods. At first, differences seen by naked eye were detected. Some of the oils could be excluded from others (coconut, linseed oils), but unfortunetaly most of the oils were too inextricable from each other. For this reason principal component analysis method and cluster analysis method were used. For ATR spectra wevenumber regions, were analysis was applied were 2800 – 3100 cm−1and 900 – 1800 cm−1. Better results were detected in 900 – 1800 cm−1 wavenuber region for both principal coponent and cluster analysis methods. For Raman scattering method spectra was analysed in two different ways. Firstly, saples were scanned 1 time and results were used for analysis. Later all samples were scanned 50 times and analysis methods were applied again. The difference of results shows that for more accurate results sample needs to be scanned more times, so that noise and signal ratio is minimized. Wavenumber regions, where analysis was applied were 3030 –2811 cm−1, 2757 – 2709 cm−1, 1766 – 1722 cm−1, 1679 – 1631 cm−1, 1482 – 1360 cm−1and 1338 – 1250 cm−1. Best results were detected in 1679 – 1631 cm−1 wavenumber region. In this work Raman scattering method results were more accurate than ATR method. Both principal component and cluster analysis methods gave similar results