Physicochemical and Trace Metals Characterization of Edible Vegetable Oils

Abstract

Edible vegetable oil samples purchased in Akure, Nigeria, were subjected to physicochemical properties and trace metals analysis. The physiochemical parameters such as acid value, iodine value and saponification value were carried out by standard methods and the levels of the trace metals (copper, zinc, iron, manganese, cadmium, nickel, lead and chromium) were determined by the atomic absorption spectrophotometric method after wet digestion. The range of mean values obtained for the physicochemical parameters of the oils:  acid value (3.59 - 9.65 mg KOH/g); iodine value (32.99 - 75.04 g I2/100g); and saponification value (187 – 207 mg/KOH/g), were within acceptable values for edible oils. The trace metals in the samples were in the range of values (mg/kg):0.10 - 0.60 (Cu); 0.07 - 2.49 (Zn); 0.13 - 0.55 (Fe); 0.01 - 0.48 (Mn); 0.01 - 0.09 (Cd); 0.01 - 0.08 (Ni); 0.07 - 0.26 (Pb); and 0.01 - 0.07(Cr). The concentration of trace metals such as Pb and Cd in the edible oils were beyond established permissible levels.