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Scientists turn cabbage into construction material stronger than concrete

Turns out scraps from onions and fruit also make for durable building products.

food scrap materials
Researchers at the University of Tokyo pressed cabbage, fruit peels and other food scraps into a strong construction material. 
Institute of Industrial Science, the University of Tokyo

The witch in the Hansel and Gretel fairy tale might have been onto something with her edible, child-enticing house. A research team at the Institute of Industrial Science at The University of Tokyo has figured out how to make durable, strong and still-edible construction materials out of food.

Pulverized cabbage leaves, seaweed and banana peels might not be as thrilling as gingerbread and pastries, but they could be part of a recipe for sustainable building products.

"Our goal was to use seaweed and common food scraps to construct materials that were at least as strong as concrete," said Yuya Sakai, a sustainable construction materials specialist and senior author of an upcoming study on the materials, in a University of Toyko statement on Tuesday. "But since we were using edible food waste, we were also interested in determining whether the recycling process impacted the flavor of the original materials."    

The team tried a heat-pressing technique usually used to compress wood powder into construction materials. Instead of wood, they vacuum-dried and then pulverized a variety of food waste items, including onion and fruit peels, as well as cabbage.  

"The processing technique involved mixing the food powder with water and seasonings, then pressing the mixture into a mold at high temperature," the university said. All of the resulting products, with the exception of the pumpkin peel, passed the team's tests for strength.   

The researchers figured out a workaround for the pumpkin issue. "We also found that Chinese cabbage leaves, which produced a material over three times stronger than concrete, could be mixed with the weaker pumpkin-based material to provide effective reinforcement," said Kota Machida, a collaborator on the project.

The molded materials remained edible, though the team didn't say if they were hard to chew. Even leaving the materials exposed to air for four months didn't change the taste, and there were no issues with rot or insects.

The development of potentially munchable materials is still in an early stage, but perhaps some day you could build a shelter and then snack on it when it's no longer needed. It would bring the witch's house into the modern age.