Effect of grilling and smoking on levels of heavy metal(loid)s and polycyclic aromatic hydrocarbons in tilapia

Abstract

The study assessed the effect of smoking and grilling on the levels of As, Cd, Hg, Pb and 18 PAH congeners in 48 composite fillet samples of O. niloticus from 2 aquatic environments on the Afram Arm of the Volta Lake. The PAH congeners were analysed by GC-MS using Agilent bond Elut QuEChERS dSPE sample preparation and a Highefficiency DB-5ms Ultra Inert GC column. For HM analysis, fillets samples were digested in HNO3 and H2O2 and analysed for As, Pb, Hg and Cd using ICP-MS with helium as the carrier gas. The mean levels of HMs in fresh fillets from both environments was As > Pb > Cd with no significant difference in the levels of Cd and Pb, but a higher mean of As in fillets of cultured O. niloticus. Ant, Pyr, Pyl and Ind were detected in fresh fillets of cultured O. niloticus, whiles only Pyr was detected in wild O. niloticus. Sixteen (16) and fourteen (14) PAHs were detected in smoked wild and cultured O. niloticus, respectively. Grilled cultured and wild O. niloticus fillets contained PAHs in the order Ant > Pyr > FL = B[a]A > Ind and Ant > Pyr > FL > B[a]A > Pyl = Ind respectively. Smoking and grilling increased the total PAHs in all fillets but decreased the level of Ind in fillets of cultured O. niloticus. Smoking and grilling had a greater effect on the mean level of detected PAHs in wild and cultured O. niloticus, respectively. The effect of smoking was, however, more significant than grilling. Smoking increased levels of Pb, Hg and As; however, its effect on As in cultured O. niloticus and Hg in wild O. niloticus was significantly high. Grilling increased the mean level of Pb in cultured O. niloticus and As in all fillets and decreased the level of Pb in fillets of wild O. niloticus. Smoking and grilling did not affect the mean levels of DBA, BP, and Cd in all fillets. The mean levels of HMs detected in the study were below the Maximum Permissible Limits, whiles the mean