Ancient Chinese brewers used red mold and cloth to filter rice alcohol

Researchers found evidence that brewers in eastern China used red mold to produce rice alcohol and filtered the liquid through cloth more than 5,000 years ago.

Ran Chen of the University of Arizona and colleagues analyzed 16 pottery vessels from Wayaoli, a site in the Zhejiang province of China. The pottery dates back approximately 5,000 to 5,300 years. The team identified five specific pottery filters consisting of connected upper and lower bowls.

Microscopic analysis revealed rice residues and remains of Monascus, a mold used to break down starch into fermentable sugars. Because Monascus also creates red pigments, the researchers believe the ancient inhabitants produced a drink with a reddish color. The vessels also contained starch from foxnut, an aquatic plant with edible seeds. The study showed that brewers likely lined the pottery filters with cloth made from bast fibers, which come from the inner bark of plant stems.

While no intact cloth survived, the presence of these fibers on the filters, but not on other household items like plates or jars, suggests they were used to strain out fine particles. The researchers note that these brewing tools were common in burial sites, appearing in about 71% of the excavated graves at Wayaoli. This high frequency suggests that preparing alcohol was a central part of the community's social and ritual life.