Rapid colorimetric detection of illegal cooking oils based on phase transfer technology

In recent years, illegal cooking oil incident led to the serious food safety risks and the negative social repercussions. In this paper, the copper ions and the cationic gold nanoparticles modified by poly(diallyl dimethylammonium) chloride (PDDA) were used as the recognition probes. Two rapid and convenient colorimetric detection methods of illegal cooking oils based on phase transfer technology were established. The results showed that qualified cooking oil mixed with 2.8% of the illegal cooking oil could be detected, and more than 5% of the illegal cooking oil could be detected accurately by naked-eye. These methods were applied in blind test for total of 235 samples; the results showed that the accurate rates of the blind tests were 95.7%. This work would be helpful for the rapid and on-site detection of illegal cooking oils.