Quality assessment of refined vegetable oils from selected major markets in Lagos Metropolis, Nigeria

Abstract

The physical compositions and chemical properties of refined vegetable oils determine their quality and storage stability. This study assessed the physical  and chemical quality indices of selected refined vegetable oils in Lagos markets. Eight samples of branded oils coded as: VEG-MMD, VEG-EMP,  VEG-DVK, VEG-GINO, VEGSNF, VEG-PWR, VEG-GDS, VEG-GLN and one unbranded, VEG-UBD, were purchased. Three categories of oils were assessed: fresh  oils (≤3 months from manufactured date), oils which were mid-way to expiration and those at verge of expiration (≤ 3 months to expiration). Results  were subjected to analysis of variance and means were separated using Duncan's multiple range test. Range of values obtained for colour, cloud-  point, moisture, percentage-purity, free-fatty-acid, iodine and peroxide values were 0.57 to 5.82 R, 4.47 to 8.43 °C, 0.03 to 0.08%, 99.27 to 99.93%,  0.07 to 0.15%, 54.74 to 119.85 and 0.15 to 0.71 mEq/kg respectively. Results showed significant (p<0.05) differences in colour, cloud-point, moisture, free-  fatty-acids, iodine and peroxide values in all categories of oils. The result also showed significant (p<0.05) difference in percentage-purity of fresh  vegetable oils and those midway to their expiry dates while no significant (p<0.05) difference existed in those at verge of expiration.