| The 1H NMR and 13C NMR spectra of soybean oil, rapeseed oil, mustard oil，sesame oil, olive oil, peanut oil, corn oil, sunflower seed oil, lard, fish oil and swill-cooked dirty oil were detected. The results showed that vegetable oils had obvious differences with lard and fish oil; in the 1H NMR spectra of swill-cooked dirty oil, there were distinctive extra peaks in the ranges of δ 6.70-5.50, δ5.10 and δ3.73,probably because the molecular structure of part triglycerides had been changed during the production, rancidity and treatment of swill-cooked dirty oil. The δ 1.26 peak in ′H NMR spectra of swill-cooked dirty oil, lard and fish oil was much higher than δ 1.30 peak. In the 13C NMR spectra of swill-cooked dirty oil, there were distinctive extra small peaks in δ 178.33, δ173.87, δ86.60, δ 68.39 and δ 65.06. These characteristic peaks could be used as proofs for the discerning of swill-cooked dirty oil. This method was simple and quick without the need for the pretreatment of samples compared with other methods. |
