Effect of frying and aluminium on the levels and migration of parent and oxygenated PAHs in a popular Chinese fried bread youtiao

• Oxy-PAHs were firstly investigated in high levels in fried foods.
• Prolonged continuous frying decreased parent and oxy-PAH content in youtiao.
• Frying temperature and aluminium content did not affect PAH concentrations.
• PAH migration rates varied significantly based on the frying oil type.

This study investigated the effects of frying conditions on the change, migration and correlation of polycyclic aromatic hydrocarbons (PAHs) and oxygenated PAHs (oxy-PAHs) in youtiao, a typical Chinese fried bread. PAH migration was evaluated using an isotope tracer method. High concentrations of oxy-PAHs, especially 9-fluorenone (1.75 μg/kg) and anthracene-9,10-dione (6.41 μg/kg), were detected. The results revealed that 1) prolonged continuous frying decreased parent PAH and oxy-PAH concentrations, 2) frying temperature and aluminium content did not have significant effects on parent PAH concentrations, 3) PAH migration rates (2.02–18.48%) varied significantly based on the frying oil type, and 4) the sum of five oxy-PAH concentrations was significantly correlated with the sum of 16 parent PAH concentrations in soybean oil-fried youtiao. Three oxy-PAHs (9-fluorenone, anthracene-9,10-dione, and 9,10-dihydrobenzo[a]pyren-7(8h)-one) were significantly correlated with their respective parent PAHs. The results might be helpful for further study and evaluation on oxy-PAHs and PAHs in fried foods.