Residue from 5,000-Year-Old Chinese Filters Suggests Red-Mold Rice Brewing

Long before distilleries, taverns or even writing, people in the Yangtze delta were already fine-tuning how they made alcohol. A new study of pottery from a Late Neolithic site in Zhejiang Province, eastern China, suggests that brewers roughly 5,000 years ago fermented a rice-based drink with red mold and likely strained it through plant-fiber cloth to make it clearer and tastier.

The site and the puzzling vessels

Wayaoli sits in Zhejiang Province and dates to about 5300 to 5000 years ago (BP). People lived there from the Late Songze period into the Early Liangzhu period, two Neolithic cultures of the lower Yangtze region. Archaeologists there found an odd pottery type called a filter: an upper bowl joined to a lower bowl, built so liquid can drain from one into the other. Filters turn up in Songze and Liangzhu sites, and in this community they appear consistently in burials. Researchers have long wondered what the vessels did. Filter shape alone cannot settle the question, because a draining vessel could also process grain or clean water.

How the team tested them

Ran Chen, now at the University of Arizona and the Stanford Archaeology Center, led the work with colleagues from the Zhejiang Provincial Institute of Cultural Relics and Archaeology and the Fuyang Museum. The team ran a multi-proxy residue analysis on pottery from Wayaoli. They looked for starch grains, phytoliths (tiny silica bodies from plants), fungal remains and microscopic fibers. They examined the filters and compared them with cooking cauldrons, storage jars and serving plates from the same site. A secondary report on the study counts 16 vessels in total, including five filters.

What they found

All five filters held rice residues and remains of Monascus, a red mold that people still use in traditional red rice wine. The authors conclude that the filters helped produce rice-based fermented drinks and that brewers added Monascus as a fermentation starter, which would have given the alcohol a reddish color. Some starch grains showed damage consistent with cooking and fermentation. Foxnut, Job’s tears and underground storage organs also appeared among the starchy plants, although the residues do not show whether brewers added them on purpose or reveal a recipe.

The fibers tell a second story. According to the secondary report, four of the five filters contained microscopic plant fibers, mostly bast fibers of the kind people weave into textiles. None showed up on the cauldrons, jars or plates. The authors infer that brewers laid bast-fiber cloth inside the filters to strain the liquid, which they say would have improved both clarity and taste. No cloth itself survives, so this step rests on the fiber traces.

Why it matters

Rice fermentation in this region has deep roots. A 2024 study from the Shangshan site reported rice fermented with Monascus about 10,000 years ago. The Wayaoli work adds something different: evidence for a filtering step, a piece of technology that makes the final drink cleaner. It also hints at how much the community cared about the result, because filters appear regularly in graves, which suggests that drinking played a role in funeral or ritual practice. The authors read the burial pattern as a sign of that ritual importance, though the offerings alone cannot say how people used the drink.

Caveats and open questions

The published abstract is freely visible but the full paper sits behind a paywall, so some details here, such as the vessel counts and fiber results, come from a summary of the paper and not from the methods section. The percentage of burials containing filters was not available to us from the sources we could read. Residue evidence also has limits: it shows what touched a pot, not exactly what the pot did every time. Future work could test how long the fiber cloth would last, what the finished drink tasted like, and whether other Liangzhu sites show the same method.

Sources

• Chen R. et al. (2026), “Investigating early brewing and filtering technology in late Neolithic: pottery residue analysis of the Wayaoli site in Southern China,” Archaeological and Anthropological Sciences, DOI 10.1007/s12520-026-02595-2
• Phys.org: How Chinese brewers refined their booze 5,000 years ago
• Anthropology.net: Neolithic Rice Alcohol Residues in 5,000-Year-Old Filters

Image credit: figure from Chen et al. (2026), Archaeological and Anthropological Sciences, via Springer Nature.