Determination of ratio of unsaturated to total fatty acids in edible oils by laser Raman spectroscopy

In this study, a homemade laser Raman spectrometer was used to examine the Raman spectra of different edible oils, such as canola, corn, soybean, sunflower, palm and coconut oils. To avoid severe fluorescence effects which tend to mask the weak Raman lines, Raman bands in the 2800-3200 cm^-1 region resulting from unsaturated and saturated carbon bonds in the fatty acids were chosen and measured the TUSFA/TFA (total unsaturated fatty acid/total fatty acid content) ratios of the various samples. Good correlation of the ratios of TUSFA/TFA of different edible oils with that calculated from manufacturers data was obtained, enabling us to measure unsaturation/total fatty acids ratio quickly and easily for any unknown oils and hence the measure the degree of possible adulteration.