China Central Television (CCTV), the state television station, first raised public worries over the quality of domestic soy sauce by uncovering a substandard workshop in central China's Hubei Province, where piles of waste human hair were found. The hairs were treated in special containers to distill amino acid, the most common substance contained in soybean sauce.

Human hair is rich in protein content, just like soybean, wheat and bran, the conventional and legally accepted raw ingredients for the production of soy sauce.