Quality Changes in Fresh and Recycled Frying Oil in Nigeria

O.B.  Adu; S.O.  Ogun; O.  Ogunrinola; O.  Fajana; S.  Olaitan; O.  Akinola; A.  Yusuf; Q.  Malik; B.O.  Elemo

doi:10.18502/jfqhc.13.1.21377

O.B. Adu Department of Biochemistry, Lagos State University, Ojo, Lagos, PMB 0001, LASU Post Office, Ojo, Lagos, Nigeria
S.O. Ogun Department of Biochemistry, Lagos State University, Ojo, Lagos, PMB 0001, LASU Post Office, Ojo, Lagos, Nigeria
O. Ogunrinola Department of Biochemistry, Lagos State University, Ojo, Lagos, PMB 0001, LASU Post Office, Ojo, Lagos, Nigeria
O. Fajana Department of Biochemistry, Lagos State University, Ojo, Lagos, PMB 0001, LASU Post Office, Ojo, Lagos, Nigeria
S. Olaitan Department of Biochemistry, Lagos State University, Ojo, Lagos, PMB 0001, LASU Post Office, Ojo, Lagos, Nigeria
O. Akinola Department of Biochemistry, Lagos State University, Ojo, Lagos, PMB 0001, LASU Post Office, Ojo, Lagos, Nigeria
A. Yusuf Department of Biochemistry, Lagos State University, Ojo, Lagos, PMB 0001, LASU Post Office, Ojo, Lagos, Nigeria
Q. Malik Department of Biochemistry, Lagos State University, Ojo, Lagos, PMB 0001, LASU Post Office, Ojo, Lagos, Nigeria
B.O. Elemo Department of Biochemistry, Lagos State University, Ojo, Lagos, PMB 0001, LASU Post Office, Ojo, Lagos, Nigeria

DOI: https://doi.org/10.18502/jfqhc.13.1.21377

Keywords: Acrylamide Polycyclic Aromatic Hydrocarbons Fatty Acids

Abstract

Background: Fried food business is common among street vendors in Nigeria, many of whom reuse frying oils repeatedly due to economic constraints and limited regulatory oversight. Repeated use of frying oil results in physical and chemical degradation, which introduces toxic compounds into the food. This work aimed to determine the physicochemical changes occurring in vegetable oils used by roadside food vendors in Morogbo, a rural area of Lagos state, Nigeria.

Methods: The safety and quality of these oils were assessed by analyzing samples collected from three street vendors on the first and fifth days of the week. Physical and chemical parameters- color intensity, viscosity, refractive index, acid value, Free Fatty Acid (FFA) content, iodine value, and peroxide value (PV)- were measured. Additionally, acrylamide and polycyclic aromatic hydrocarbons (PAHs) concentrations were quantified using High Performance Liquid Chromatography (HPLC). Fresh oils from the vendors served as controls. Results were expressed as the mean ± Standard Error of Mean (SEM) and analyzed using one-way analysis of variance (ANOVA) followed by Tukey’s Honestly Significant Difference (HSD) post-hoc test. Values of p<0.05 were considered statistically significant. Statistical analyses were performed using GraphPad Prism version 10.4.1

Results: There was significant difference (p< 0.05) in the refractive index, viscosity, Peroxide Value (PV), and Free Fatty Acid (FFA) content between the control and the recycled oil. However, there was no significant difference in iodine value and color intensity between the fresh and recycled oil. All the oil samples, including the control, had high acrylamide while the recycled oil had elevated concentrations of some Polycyclic Aromatic Hydrocarbons (PAHs) like benzo[a]pyrene.

Conclusion: This study highlights the significant deterioration in the safety and quality of frying oils used by street vendors in the Morogbo rural area of Lagos State.