Can You Fry Things in Space?

Can the good old American tradition of caking foods in grease continue in the vast recesses of space?

Fried food

Space is a hostile place. You cannot breathe, or scream, or really do much of anything without a spaceship to keep you safe. And even inside the spaceship, things don't follow the same rules they do on Earth. Crying, washing your hair and boiling water are all totally different in space. But what about frying? Can the good old American tradition of caking foods in grease continue in the vast recesses of space?

Thankfully, scientists are on top of this. In a recent paper published in Food Research International, two researchers investigated the "effect of increased gravitational acceleration in potato deep-fat frying." Philip Ball at BBC Future explains why frying might be different on a space ship:

For frying and boiling, convection is an essential part of the process. The rate at which foods heat up in water or oil is affected by the way hot liquid circulates. On Earth, the hot liquid at the base of a pan rises because it’s less dense than the cooler liquid above. Yet this convection won’t happen in zero gravity. Conversely, in increased gravity convective effects should be more pronounced.

In order to study these variations, the researchers stuck a deep-fryer onto a giant centrifuge at the European Space Research and Technology Center in the Netherlands. The centrifuge can create up to 9gs of force on the poor french fries, but as they watched the deep-fryer spin they noticed that it was at 3g that the frying began to change. You see, as the centrifuge spins and the g-forces rise, the bubbles in the oil get smaller and smaller. This actually makes for a nicer fry, since tiny bubbles make a nice thick crust. But when you get to 3g, the force on the bubbles is so small that they actually get stuck to the potato. Go above 3g, and the crust separates from the potato all together.

So what does that mean for astronauts? Well, the convection part is problematic. In fact, the researchers realized that at zero g, there would be no convective force, and thus soggy fries without a crust. So for now, no french fries for astronauts.

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