You might want to save those leftover egg whites at breakfast. Researchers at Princeton University found a way to use them to filter salt and tiny bits of plastic from sea water. It’s a method that could be cheap and reliable, and could be used on a large scale.

 The team was trying to mix up a new recipe for aerogel—a material that’s mostly air or other gas. It’s extremely light weight, but it’s versatile. It’s used for insulation, water filtration, and even to catch bits of comet dust.

But the researchers wanted a version that was much more efficient at filtering water. So they mixed carbon with various breakfast ingredients—different bread recipes, eggs, and others. After a lot of trial and error, they settled on egg whites. They made a good aerogel even if the eggs had been cooked or whipped like a merengue.

The result was lighter than other aerogels—a cubic yard would weigh about six and a half pounds; by comparison, the same volume of sea water weighs more than 1700 pounds. And the egg whites filtered more than 98 percent of the salt from sea water, and missed only one in 20,000 bits of plastic.

At first, the team used the same eggs you buy in the grocery store. Later, it worked with similar proteins found in other products. The researchers say their aerogel would be more efficient and less expensive than current filtration systems—straining sea water with a material developed from a common breakfast food.