Comparative study of properties and fatty acid composition of some neat vegetable oils and waste cooking oils

Vegetable oils have been used as a feedstock for fatty acid methyl ester (FAME) production. The high cost of neat vegetable oil and its impact on food security have necessitated its replacement as a feedstock for FAME by used vegetable oil, also known as waste cooking oil (WCO). This study compares the properties and fatty acid (FA) compositions of samples of neat vegetable oil with those of samples of WCO, collected from restaurants and takeaway outlets at the point of disposal. The samples were subjected to property determination and pyrolysis gas chromatography mass spectrometer (PYGCMS) analysis. Analysis showed that degree of usage and the type of food items originally fried in the oil substantially affected its properties and FA composition. Density of neat vegetable oil varied between 904.3 and 919.7 kg/m(3) and of WCO between 904.3 and 923.2 kg/m(3). The pH of neat vegetable oil varied between 7.38 and 8.63 and of WCO between 5.13 and 6.61. The PYGCMS analysis showed that neat palm oil contains 87.7% unsaturated FA and 12.3% saturated FA, whereas neat sunfoil contains 74.37% saturated FA and 25% polyunsaturated FA. Generally, neat vegetable oils consisted mainly of saturated FAs and polyunsaturated FAs, whereas the WCO contained mainly of saturated FAs and monounsaturated FAs. This research confirms the suitability of WCO as feedstock for FAME.