Quantitative Analysis of Polycyclic Aromatic Hydrocarbons in Heated Soybean Oil

Polycyclic aromatic hydrocarbons (PAHs) are compounds ubiquitous in the environment and are harmful to human health. PAHs can easily enter the human body through the consumption of edible oils due to their high lipophilicity. Most of the published papers investigating PAH concentrations in edible oils focused on virgin (i.e., unheated) samples instead of those being used in cooking at temperatures higher than room temperature. This study aimed to provide a comprehensive landscape of PAH concentration in soybean oil by simulating a more realistic scenario of oil consumption—eating oil being cooked at different temperatures. I quantified the concentration of PAHs in soybean oil after being heated to four temperatures (100°C, 150°C, 190°C, and 222°C) with three durations (5 minutes, 30 minutes, and 60 minutes). Liquid liquid extraction (LLE), tandemly followed by solid phase extraction (SPE), were used to extract PAHs from the matrix and remove interferences from the extract. PAH concentrations were determined by a gas chromatography mass spectrometer (GC-MS). With extended heating time, concentrations of ACE and FLU showed a rising trend in 100°C and 150°C data groups but a falling trend at higher temperature data groups. Concentrations of PHEN and ANTH had a sharp increase when the oil was heated to 222°C and held one hour. Concentrations of B[a]A, CHRY, and B[a]P rose slightly with extended heating time at almost all temperatures. Concentrations of ACY, FLTH, B[b]F, B[k]F, IND, D[ah]A, and B[ghi]P were low and nearly undetectable. Only NAP concentrations in 100°C-oil samples were over the maximum residue level (MRL) set by China’s national standard. Diverse concentration changes of different PAHs after the oil was heated suggested that B[a]P alone or a combination of several PAHs are not sufficiently representative to be the marker or surrogate for PAH exposure. This diversity also resulted in an undetermined correlation between the PAH remaining in the oil and heating temperatures and hold time. The information of PAHs increment caused by heating soybean oil was incomplete because of data unavailability for the vaporized part.