| Dough sticks were fried continuously using peanut oil, rapeseed oil and sunflower seed oil, and then the formation and correlation between polar components (PC) and oxidized triglycerides polymers (TGP) or polycyclic aromatic hydrocarbons (PAHs) in fried oils were studied. The results showed that the contents of PC, TGP and PAHs increased with frying time prolonging. In the process of 32 h frying experiment, the contents of PC, TGP and PAH16 in peanut oil increased from 3.34%, 0.43% and 16988 μg/kg to 29.00%, 16.92% and 282.66 μg/kg, respectively. The contents of PC, TGP and PAH16 in rapeseed oil increased from 4.02%, 0.51% and 18.85 μg/kg to 25.80%, 15.55% and 4292 μg/kg, respectively. The contents of PC, TGP and PAH16 in sunflower seed oil increased from 2.43%, 0.42% and 21.49 μg/kg to 34.19%, 24.76% and 51.95 μg/kg, respectively. Comparatively, after frying for 32 h, rapeseed oil had the lowest growth rate of PC content among these three kinds of oils and within the limited quantity of national standard (≤27%). Besides, PC content was significantly and positively correlated with the contents of TGP and PAH4 during frying. In this case, the contents of TGP and PAH4 could be predicted based on PC content. In all, besides testing and controlling PC content according to national standard, the change of TGP and PAHs in frying oil should also cause great concern to ensure the safety of frying oil comprehensively. |
