Hitting the books: The ancient technology behind astronaut ice cream
It’s been one week since astronauts Robert Behnken and Douglas Hurley made history by successfully riding SpaceX’s Falcon 9 rocket up to the International Space Station. This calls for a celebration! And what orbital party would be complete without the most American of freeze-dried fare, astronaut ice cream? But while the cold and crunchy confection is most often associated with our most technologically advanced industry, the technique’s development dates back to ancient times.
In his latest book, Ingredients: The Strange Chemistry of What We Put in Us, author and chemist George Zaidan breaks down the techniques and technologies we use to process the foods and products we put in and on ourselves and how, in turn, those things impact our health and well-being. In the ecerpt below, Zaidan explains how the Aymara people, an indigenous nation spread throughout Bolivia, Peru and Chile, pioneered the process of freeze drying foods for indefinite storage — as well as to leech out pesky poisons.
From INGREDIENTS by George Zaidan, published by Dutton, an imprint of Penguin Publishing Group, a division of Penguin Random House, LLC. Copyright © 2020 by George Zaidan
Eating clay (or other minerals) to detoxify potentially dangerous food is arguably the very first thing we did as a species that could be considered “processing”: we took something from nature and—before eating or using it—we changed it in some way. At its heart, processing is simply changing nature to suit our needs. Now, if you’re thinking, “Eating clay with potatoes isn’t processing potatoes; it’s just eating two things at the same time,” I understand. Dipping potatoes into a clay slurry might fall just outside the broadest possible definition of processing; it’s basically like dipping fries in ketchup, if the fries were toxic and the ketchup was the antidote. So let’s take another example, also involving the Aymara and poisonous potatoes.
As a kid, I would make annual summer pilgrimages to the National Air and Space Museum in Washington, D.C. The highlight of these trips was always buying space ice cream, a small rectangular lump of freeze-dried ice cream: regular old Earth ice cream that had been simultaneously frozen and dried, leaving the flavor and (most of) the texture, but removing all the water. Freeze-drying something is a pain in the ass. With modern technology, the process goes something like this:
1. Get a strong vacuum pump, some alcohol and dry ice, and some leakproof piping and flasks.
2. Freeze the thing you want to freeze-dry, then put it in a flask.
3. Connect the flask to some pipe, then connect the other end to a second flask.
4. Dunk the second flask into an alcohol/dry-ice bath.
5. Connect the second flask to a vacuum pump.
6. Turn on the pump, and let run for at least twelve hours.
7. A few hours in, heat the flask gently with one of those red lightbulbs that keeps you warm after a shower.
8. Wait a few more hours, and finally . . .
9. Enjoy your NASA ice cream.
Here’s how this works: the vacuum pump lowers the pressure to almost zero, which causes the frozen water in the ice cream to start to evaporate—without melting. Heat from the light helps this process along. As the water vapor enters the second flask, it freezes. Eventually you end up with freezing cold, bone-dry food.
Essentially what you’re doing is using low pressure, extreme cold, and gentle heat to remove solid water (ice) out of a frozen food without melting the food first. Freeze-drying food seems like a modern technology. But the Aymara figured out how to freeze-dry potatoes without pumps or pipes or a freezer. Here’s how they do it:
1. Get some wild toxic potatoes.
2. Freeze the potatoes by leaving them outside overnight at high altitude.
3. Trample the frozen-solid potatoes like a French winemaker tramples grapes.
4. Put the trampled potatoes in a loose wicker basket, put the basket in a stream or creek, and leave for a few weeks.
5. Put the potatoes on your front doorstep and let them freeze overnight and dry out in the daytime, squeezing occasionally, then leave for another few weeks.
6. ¡Y voilà! Freeze-dried potatoes.
This method is astonishingly similar to modern-day techniques. Instead of a vacuum pump, the Aymara use their environment: at high altitudes, the pressure is low. Instead of warming lightbulbs, the Aymara use the sun. The Aymara method is even a bit more sophisticated than modern methods: trampling the potatoes and then leaving them in running water leaches out about 97 percent of the toxins in the wild potatoes.* And not only is the final product edible without gastrointestinal distress, it’s much more storable. Fresh potatoes might last for a year; leached and freeze-dried potatoes can last for twenty (some people say in-definitely). If you were a member of a society like the Aymara, having a ready supply of edible stored carbs that would last you through a two- or three-year famine might just be the key to your survival.
The historical record is not clear as to whether or not this is the world’s first processed food, but it is clear that this is processing: taking something from nature and changing it to suit our purposes—in this case making it nontoxic.
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