Formation mechanism of polycyclic aromatic hydrocarbons in grilled beef and the mitigative effect of flavonoids

Polycyclic aromatic hydrocarbons (PAHs) are found in many common foods and increase the risk of cancer in humans. This study systematically screened the components that may be related to the formation of PAHs by an excessive addition of 19 amino acids and glucose in the beef patties. Phenylalanine and glucose exhibited the potential as promoters of PAHs, while lysine, aspartic acid, glutamic acid, valine, and methionine exhibited excellent potential as inhibitors of PAHs. Subsequently, a chemical model containing phenylalanine and glucose was established to confirm their roles as precursors of PAHs. The formation mechanism of PAHs showed that naphthalene was first formed as a basic structure, and then, PAHs with more rings were further formed through substitution, addition reactions, or intramolecular cyclization reactions. The mitigative effects of four flavonoids on total PAH contents were in the order: kaempferol > naringenin (better for individual PAH) > myricetin > quercetin (contradictory), which suggested that the antioxidant ability or radical scavenging capacity of flavonoids may be one of the pathways for PAH inhibition.