Quality assessment of fried palm oils using fourier transform infrared spectroscopy and multivariate approach

Palm oil is one of the important commodities of Malaysia and is superior for frying due to its high oxidative stability and high content of unsaturated fatty acids. The quality of frying oil will decrease with time and repeated cycles of frying, and may subsequently affect the safety of the food. Several parameters such as peroxide value (PV) and conjugated diene value (CDV) have been used conventionally to monitor the quality of edible oils. In this study, Fourier Transform Infrared (FTIR) spectroscopy was used to evaluate the quality of palm oils after repeated cycles of frying. FTIR spectra were recorded from 4,000 to 400 cm-1, and analysed using multivariate data analysis (MVA) to select important spectral regions and identify clustering pattern among samples. FTIR frequencies at 1,744 and 2,922 cm-1 were found to be the most discriminating variables influencing the separation between fresh and used frying oils. The correlations between peak areas at 1,744 and 2,922 cm-1 with PV and CDV values were also determined, yielding linear regression models with high correlation coefficient, R2. The results demonstrate that FTIR can be used as a rapid, reliable and accurate analytical method for the quality assessment of frying oils