A restaurant in Wuhan, capital of Hubei Province, was found to have used formaldehyde to soak about 2,000 kgs of beef tripe and tendons worth about 100,000 yuan (USD 15,000), Jianghan People's Procuratorate said.
Beef offal is a common ingredient in Chinese food.
Soaked in cancerogenic formaldehyde, it appears fresh and white.
The restaurant owner with his son and other staff added the banned addictive to the offal in February last year, state-run Xinhua news agency reported, without giving details of the prison terms.