Chemical properties, heavy metals and polycyclic aromatic hydrocarbon level of smoked mackerel (Scomber scombrus) in Abeokuta North and South Local Government Areas of Ogun State, Nigeria

Abstract

Smoked mackerel (Scomber scombrus) is commonly consumed in Abeokuta metropolis. However, its consumption may pose food safety risk because of poor handling practices. This study assessed the quality and safety of smoked mackerel in Abeokuta North and South Local Government Areas (LGAs) of Ogun State Nigeria. Smoked mackerel samples were collected aseptically from two processors each in three different locations of Abeokuta North and South LGAs. Chemical quality indices (proximate composition, heavy metals, and polycyclic aromatic hydrocarbons) were carried out using standard methods. Data obtained were analyzed using analysis of variance and means were separated using Duncan multiple range test. The moisture, ash, fat, crude fibre and protein contents of the smoked mackerel ranged from 51.30-61.84%, 1.03-2.54%, 10.02-12.80%, 0.20-1.09% and 24.97-34.44%, respectively. Also, pH, peroxide, free fatty acid, thiobarbituric acid, total volatile base-nitrogen and trimethylamine values ranged from 5.44-6.21, 2.49-8.03 meq./kg, 0.01-0.02%, 0.28-0.32 mg malonaldehyde/ kg, 8.69-15.95 mgN/kg and 1.74-6.21 mgN/kg respectively. Lead, cadmium, mercury and chromium contents ranged from 0.86-0.91 mg/kg, 0.37-0.41mg/kg, 0.01-0.04 mg/kg and 28.67-32.44 mg/kg, respectively. All the parameters evaluated were found to be significantly different at (p < 0.05). Polycyclic aromatic hydrocarbons (PAHs) detected in smoked mackerel include fluorene (3.86-156.17 ppm), phenanthene (0.29-0.75 ppm), anthracene (0.26-5.95 ppm) and flouranthene (4.15-55.72 ppm). In conclusion, this study revealed that smoked mackerel had higher concentrations of cadmium, chromium, lead and
PAHs were generally above the maximum permissible limit set by World Health Organization.

Keywords: Polycyclic aromatic hydrocarbons (PAH), heavy metals, smoked mackerel