A man has been arrested in northern China after he boiled up barrels of "fake" congealed duck blood in his small house and added the preservative formaldehyde before selling it as a gourmet delicacy, according to a media report. Genuine congealed duck blood is prized by diners in many areas of China, but the man used cheaper cow and sheep blood, along with the chemical, and passed it off as the real thing, the news website Sina.cn reported. The authorities in Ankang in Shaanxi province were first alerted shortly after he started boiling up the blood in February because of the smell coming from his house, the report said. Twenty boxes of his products were seized. Three months later the authorities were tipped off that he had started production again and his premises were raided. The authorities said they found animals parts, several large pots and a coal-burning furnace on the ground floor of the man’s home, while he lived on a floor above. Officials were quoted as saying that the room where he worked was “overflowing with blood”. He had bought the sheep and cattle blood from a nearby slaughterhouse, the report said. Five barrels of congealed blood were seized, according to the article. The media in China regularly report on food safety scandals. The government announced earlier this week that police had broken up gang that had produced 20,000 tonnes of lower-grade industrial salt and sold it to stores and restaurants as table salt. Industrial salt is used in a huge number of processes including making glass, polyester and fabric.