How Wasabi Can Help Preserve Ancient Papyrus

Researchers say the green horseradish-like paste can fight fungal infections without damaging fragile pigments

Wasabi, which is commonly eaten with sushi, is also an effective preservation tool. Charly Triballeau / AFP via Getty Images

A new study has found that wasabi—the spicy green paste that pairs well with sushi—can be used as a tool to conserve ancient papyrus scrolls.

Thousands of years ago, papyrus was used to make a number of items, such as sails, boats and baskets. It was also a writing material, and rare ancient texts were often composed on papyrus. 

Made with stems from the Cyperus papyrus plant, the organic material is fragile, sometimes falling victim to fungal infections. “Fungi can grow deeply,” causing damage such as “cracking” and “paint loss,” according to the researchers.

Enter wasabi, a plant that’s native to Japan, Korea and the Russian Far East. According to the study, which was published this month in the Journal of Archaeological Science, wasabi vapors can actually help fight off fungal infections on ancient papyrus without causing harm to the fragile material itself (or the pigments painted onto it).

“The bio-deterioration of papyri is a worldwide problem,” lead author Hanadi Saada, a researcher at the Grand Egyptian Museum in Egypt, tells New Scientist’s Jeremy Hsu.

Scroll of Hunefer
Many ancient texts were written on papyrus, and surviving samples are prone to fungal infections. Universal History Archive / Universal Images Group via Getty Images

Saada’s team began by recreating 1,000-year-old papyrus. Over the course of 120 days, the researchers heated samples of the material to 212 degrees Fahrenheit to simulate years of wear. Next, they exposed the papyrus—which they had painted with red, yellow and blue pigments—to several fungal species commonly found on ancient scrolls.

To treat the infected scrolls, scientists mixed water and wasabi powder until the resulting mixture reached a “dumpling-like state.” They placed the wasabi on aluminum foil near the papyrus, leaving the replica scrolls exposed to the wasabi vapors.

After three days, the scientists checked back in and found that the contamination had vanished. The exposure to the wasabi vapors even increased the sample’s tensile strength by 26 percent.

Importantly, the vapors also didn’t cause any noticeable change to the color of the samples. The chemical makeup of the pigments was affected “only negligibly,” according to Artnet’s Verity Babbs. In the past, other disinfectants used to treat ancient artifacts have damaged papyrus “possibly as badly as the fungus itself.”

Many of today’s preservation techniques are designed to avert damage in the first place, making them a “passive way of preventing fungal growth and deterioration,” Jessica Byler, a conservator at the Penn Museum in Pennsylvania, tells New Scientist. But because these methods aren’t perfect, Byler adds that her team is interested in “[learning] more about innovative eco-friendly techniques within the field of conservation.”

The new wasabi solution has additional benefits beyond its effectiveness in preserving pigments: Compared with traditional disinfectants, wasabi is “safe for humans [and] greener to the environment,” write the researchers.

The Grand Egyptian Museum, located in Giza, is already planning to use the new preservation technique to protect ancient papyri. Meanwhile, the researchers will be studying whether wasabi can be used on materials such as textiles and paper.

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