In a major food safety crackdown, 13 underground workshops were shut down and more than 3,584 tons of "gutter oil" were seized, the official Xinhua news agency reported.
"Gutter oil" is made by taking used up cooking oil, often left over from restaurants, along with spent animal fat, and reprocessing it into edible oil to be sold to restaurants.
Investigators found suspects used not only waste fat and oil, but also fat from rotten meat and slaughterhouse waste.
Xinhua reported the nationwide food safety campaign, launched in August 2011, responded to several food scandals that came to light last year. Such scandals included not only gutter oil, but also the practice of adding the carcinogen clenbuterol to pig feed to produce lean meat.