While most cooks would be dismayed if their bread burned while it was baking, researchers from China's Harbin Institute of Technology have been busy torching their loaves to create a material known as carbon foam. The lightweight material serves as a thermal insulator, electromagnetic shield and electrical conductor, and it costs, well, just about as much as a loaf of bread.

Carbon foam itself is nothing new. Because of its mix of low weight and high performance, it's been of special interest in the aerospace industry as an insulating material but currently, many methods of producing it can be costly.

Making carbon foam from food also isn't new. Previously, the material has been made from such edibles as bananas and watermelons. But in those cases, it was difficult to finely tune the end result to produce the foam with exactly the right characteristics for the job, as the size of the cells inside the material were inconsistent.

The new method begins with a simple loaf of bread. But once the initial loaf is made and dried in an oven for 18 hours at 80 ºC (176 ºF), it is put into a special furnace that uses argon gas to blast it into the carbon foam.

The resulting foam was found to have the same characteristics as other carbon foams. It was strong, a good temperature insulator, lightweight and it provided shielding from electromagnetic waves. It was also more flame-resistant than current carbon foams, so it could make a fine insulation for planes, spacecraft or even homes. The process is also, obviously, low cost considering the ingredients used.

What's especially interesting about the bread-based process though, is that based on the amount of water and yeast the researchers introduced into the dough, they were able to change the pores inside the foam, meaning that the process was tunable. In other words, it was possible to create foams with different pore sizes based on different needs.

The results of the process were published today in the American Chemical Society journal, Applied Materials & Interfaces.

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