TAMBO VIEJO — Researchers discovered two samples of 500-year-old freeze-dried potatoes in a storage room at the Inca site of Tambo Viejo on Peru's south coast during the 2024 field season. The findings were published in the Journal of Field Archaeology on May 1, 2026, with Lidio Valdez as the principal investigator.

The freeze-dried potatoes, identified as chuño, were found inside a clay pot sunk into the dirt floor of the storage room. "Almost at the base of the vessel, the two samples of freeze-dried potatoes were found," said Valdez, an adjunct professor in the Department of Anthropology and Archaeology at the University of Calgary. "They showed me without knowing what they were, and right away I said: chuño!" The discovery predates the Spanish invasion of the Inca Empire.

This marks the second time chuño has been recovered from an Inca archaeological site. Chuño is produced by exposing potatoes to nighttime frost and daytime sun until most moisture evaporates. This technique requires high elevations, specifically above approximately 11,800 feet (3,600 meters), where severe frost occurs regularly. The chuño found at Tambo Viejo was transported from the highlands to the coast. Llamas were used to transport goods across the Inca Empire. "Chuño being a light product probably also made its transportation easier," Valdez said.

The Acarí Valley, where Tambo Viejo is situated, has extremely dry conditions that helped preserve the freeze-dried potatoes. Potatoes are approximately 80% water and typically rot within a week in warmer, lower elevations. Along with the chuño, an Inca pottery fragment and a broken spindle whorl were found. A spindle whorl is a tool used for spinning fibers into yarn or thread. Katrina Bettcher, an independent archaeologist, co-authored the study.

The Inca used a similar drying method to preserve meat, producing a product called charki. The word 'jerky' is derived from the word 'charki'.