What is freeze-drying? A technique that helped Whirlpool take food to the Moon

We’ve all heard of the Punjabi doodhwala who adapted a washing machine to make lassi. But what about the company best known for washing machines that catered the first Moon landing, 50 years ago this week?

Whirlpool got a contract to develop a space food kitchen in 1960. The US was trying to catch up with the Soviet Union, which had launched the Sputnik satellite three years earlier. Using the expertise of American corporations was an obvious shortcut and Whirlpool was making home appliances for cramped spaces. This was extended to other space food problems. For example, crumbs which can’t just be brushed away in a zero-gravity environment because they float and cause problems if they get into machines. So the first space foods were pastes packed in tubes squeezed directly into the eater’s mouth.

The problem with tube eating, as Mary Roach notes in Packing for Mars, her entertaining book on the practical side of space travel, is that “it requires bypassing the two quality control systems available to the human organism: Looking and sniffing”. Food pastes might work for babies, but adult astronauts loathed them.


They hated the next solution too: Bite-sized cubes of compressed food sealed in films of fat to stop breakaway crumbs. These worked when spaceflights lasted just hours, but over days and weeks, it was evident that less demoralising foods were needed.



This is where food corporations, already skilled at creating appealing products for consumers, really scored. Dehydrated fruit juice didn’t reconstitute well in space, but an existing artificial drink powder called Tang did fine — and got a huge boost when the astronaut John Glenn drank it in 1962. Many food preservation techniques developed for the space programme were dead-ends, or took decades to become successful. For example, Whirlpool mixed gases to create atmospheres in which salad leaves stayed fresh longer; it was only in the 1990s that this became a huge business for supermarkets (not spaceships).

One of the oddest challenges was simply boiling water. A Whirlpool video explains that unlike on Earth, where water heated from below a pot rises to warm the whole pot, in zero gravity this doesn’t happen, so the whole container must be heated at once. This was possible by the time the Moon missions took place, and is why the lunar landers could enjoy hot, rehydrated meals.

Dehydration was a key technology, making foods lighter and less easy to spoil. Freeze-drying received a particular boost from the space program. Drying at high temperatures cooks food a bit, but freeze-drying changes it much less. A dried grape is a raisin, but a freeze-dried grape tastes like a fresh grape that just happens, weirdly, to be crisp and dry.

Many fruits are being freeze-dried now in India, as part of efforts to prevent produce going waste. Bananas, chikoos, mangoes and others can be eaten in pieces, as a snack, or pulverised, to be used in intense-tasting milk shakes. It’s a delicious way to bring the Moon landings into your meals.