The effect of gas versus charcoal open flames on the induction of polycyclic aromatic hydrocarbons in cooked meat: a systematic review and meta-analysis

Purpose Open flames of gas and charcoal can induce polycyclic aromatic hydrocarbons (PAHs) in cooked meat. The current study aimed to compare the effect of gas and charcoal open flames on the induction of PAHs in cooked meat using a meta-analysis approach. Methods A systematic review of the literature was conducted electronically based on the PRISMA guidelines. Experimental studies comparing the PAHs content of cooked meat over open flames of gas and charcoal were searched using the appropriate keywords until June 2018. Results Of 1137 papers retrieved, 7 with a total sample size of 474 meat samples were used in the meta-analysis. The mean difference (MD) between the gas and charcoal cooking methods in the induction of each PAH was 2.053 mu g/Kg. (95%CI: 1.022-3.085 mu g/Kg; P < 0.001). The subgroup analysis of 17 trials indicated the difference between the two cooking methods increases when red meat rather than white meat is cooked (MD in red meat: 3.499 mu g/Kg; 95%CI: 2.030-4.967; P < 0.0001 vs. MD in white meat: 3.319 mu g/Kg; 95% CI: 1.689-4.950; P < 0.0001). Interestingly, studies that analyzed meat samples for fewer PAHs (cut-off <= 7) found a much wider difference between gas and charcoal-cooked meat (MD: 5.106 mu g/Kg; (95% CI: 2.162-8.049; P < 0.001 in studies with <= 7 PAHs vs. MD: 1.447 mu g/Kg; 95% CI: 0.628-2.266; P < 0.001 in studies with >7 PAHs). Conclusions It is necessary to avoid open flames of charcoal as the heat source or change the geometry of charcoal-fired cookstoves to prevent fat dripping on the fire and thus, excessive PAHs induction.