Chinese police have seized over 30,000 tons of tainted chicken feet, common on restaurant menus in China, in the latest food scandal to hit the country.

Authorities have detained 38 people involved in the sale of the chicken feet in provinces including the eastern province of Zhejiang, the official Xinhua news agency reported on Tuesday.

The arrests followed raids on nine supplier factories in nearby Jiangsu, Anhui, Henan and Guangdong provinces, Xinhua said, adding police found that excess hydrogen peroxide was being added to the meat.

China has been rocked by a number of high-profile food scandals from milk powder tainted with industrial chemical melamine to re-used “gutter oil” for cooking. Earlier this month, US ketchup maker H.J. Heinz Co apologized to Chinese consumers as it recalled some infant cereal due to excess levels of lead.

Last month, McDonald’s Corp and KFC-parent Yum Brands Inc were caught up in a scandal after it was found that workers at a China-based supplier had used expired meat and doctored food production dates.

Zhejiang police had broken up 35 sales networks for the tainted chicken feet, valued at over 300 million yuan ($48.76 million), local police said in a microblog post. Eleven suspects were still on the run, the police said.

Chicken feet are a popular dish in China where they are often broiled or put in soups. China was the largest buyer of chicken feet exported from the United States last year.

In 2013, Xinhua reported that China had seized 20 tons of chicken feet, some of which had production dates on their packaging going back as far as 1967.

Chinese authorities also said on Monday that a local chef had gone on trial accused of painting abalones and goose feet to make the dishes visually more appealing, Xinhua said.