Effects of storage time and temperature on toxic aldehydes and polycyclic aromatic hydrocarbons in flavouring oil gravy during storage

Abstract The health risk of toxic aldehydes has attracted substantial attention. Among these aldehydes, 4-hydroxy-2-trans-hexenal (4-HHE) and 4-hydroxy-2-trans-nonenal (4-HNE) are two of the most toxic. In addition, polycyclic aromatic hydrocarbons (PAHs) and oxygenated aromatic hydrocarbons (OPAHs) have also been widely investigated because of their carcinogenicity. Changes in these contaminants were investigated in three flavouring oil gravies during consecutive storage at different storage temperatures. The concentrations of all the contaminants increased with storage time and higher temperature. The enrichment rates of 4-HHE and 4-HNE in the gravies stored at 37 °C were approximately 2.5 times that of those stored at 4 °C. The concentration of total PAHs at 25 °C increased from 1.72 to 3.17 μg/kg to 22.44–36.20 μg/kg. Similarly, the concentration of total PAHs showed the largest increase at 37 °C. Acid values and peroxide values, which were within the regulatory limits in China after storage, were also determined using titrimetry. In addition, two other toxic aldehydes, acetaldehyde and propionaldehyde, were found in the gravies. These results might help control the concentration of 4-HHE, 4-HNE, PAHs and oxygenated PAHs (OPAHs) in foods rich in oil.