U.S. researchers say they've discovered a class of nanostructures that could be used for gas storage and food or medical technologies -- oh, and they're edible.

Northwestern University scientists say the porous crystals are the first known all-natural metal-organic frameworks that are simple to make. Most MOFs are made from petroleum-based ingredients, but you can pop the Northwestern MOFs into your mouth and eat them -- and the researchers have, the university says.

"They taste kind of bitter, like a Saltine cracker, starchy and bland," Ronald A. Smaldone, a postdoctoral fellow at Northwestern, said. "But the beauty is that all the starting materials are nontoxic, biorenewable and widely available, offering a green approach to storing hydrogen to power vehicles."

Metal-organic frameworks are well-ordered, lattice-like crystals. Within their very spacious pores, MOFs can easily store gases such as hydrogen or carbon dioxide, making the nanostructures of special interest to engineers as well as scientists.

"Using natural products as building blocks provides a new direction for an old technology," Jeremiah J. Gassensmith, a postdoctoral fellow in the Northwestern lab said.

"The metal-organic framework technology has been around since 1999 and relies on chemicals that come from crude oil," said Ross S. Forgan, also a postdoctoral fellow in the lab. "Our main constituent is a starch molecule that is a leftover from corn production."

The research group included a trio of postdoctoral fellows in chemistry at Northwestern and colleagues from the University of California, Los Angeles and the University of St. Andrews in England.