Ancient Freeze-Drying Techniques


Many people today would be lost -- and hungry -- without refrigerators, freezers and neatly packaged foods preserved in boxes, cans, jars and plastic. It's easy to forget that these are comparatively new ways of storing and preserving food. For the vast majority of human history, food was stored without refrigeration and the often time-consuming labor of food preservation done with the very real possibility of starvation always in mind. Geography and climate had a strong influence on regional food preservation methods. Ancient freeze-drying techniques evolved in particular types of environmental settings.

Something in Common

  • Peru's prehistoric Incas and Japan's ancient Buddhist monks were as dissimilar culturally as any two groups could be. The Incas' religion featured blood-letting rituals and the elaborate sacrificing of children, adults, and animals; whereas non-violence was central to the Buddha's teaching. Many Buddhist monks and followers were vegetarians who believed it was wrong to kill animals. The two groups had completely different worldviews, reflected in many aspects of their cultures, including diet. Even with such radical cultural differences, the influence of geography and climate was strong to lead the Incas and the monks along similar paths of discovery. The Peruvian Incas inhabited the highlands of the Andes mountains and the monks who brought Buddhism to Japan established a monastery on Mount Koya. In both places, freeze drying emerged as an important means of food preservation.

They Shared Something Special

  • Far into the modern era, most people did one or the other; They either froze their food or dried it, but not both. Freeze drying combines cold, pressure and sometimes heat to extract more than 95 percent of water weight, without damaging food cell structure, texture or nutritional quality. The process creates an inhospitable environment for bacteria, dramatically increasing the lifespan of well-sealed foods. It wasn't until the development of modern equipment that had the ability to supply precise timing, temperatures and pressure that freeze drying began in a widespread commercial manner. Nestle began selling their freeze-dried instant coffee in 1938. Freeze drying continued to evolve through the twentieth century and into the present. What allowed the Incas and the Buddhist monks to freeze dry centuries sooner was the special nature of their physical environment. Their high altitude mountain regions featured just the right balance of dry cold and low atmospheric pressure to make freeze drying work.

Old-School Techniques

  • The Buddhist monks and Andean Incas learned how to freeze dry during periods of crop failure, which could mean starvation and death. This means of food preservation allowed food to be stored for years, an important way of increasing food security during what were often insecure times. The process, like that of today -- though taking far longer -- involves cycles of freezing and drying, extracting and evaporating away moisture. The Buddhist monks worked with tofu, while the Incas freeze-dried potatoes, meat and other foods. Potatoes offer a good example of the basic process. After harvest, they'd be allowed to freeze; next, they were stomped into a paste. That paste was put through cycles of night freezing, evaporation under the sun, and freezing again for days to remove moisture; then, it was carefully prepared for storage and put away.

Foods Still Used Today

  • Koya-dofu is the name of the freeze-dried tofu created by the monks on Mt. Koyo so many centuries ago. It was a new food product back then, but it's still on the market today. The freeze-dried potato paste the Incas made came to be called chuno, which is also still in use today. It still serves its original purpose, as a hedge against hunger and, even today, is made in many villages the same way it always has been. In August of 2013, the Associated Press reported that a bag of chuno large enough to last for a year cost about 10 dollars.

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