This sounds like the premise of a comedy sketch, but researchers at the University of Tokyo’s Institute of Industrial Science, led by Yuya Sakai, have developed a method that can recycle food waste into a building material stronger than concrete, but still edible and tasty.

According to United Nations data, 1.3 billion tons of food are wasted every year in the world. Some of them are lost due to inefficiency in the food chain, but there is also a lot of waste, because the product is considered substandard or has exceeded its shelf life, or because waste and leftovers are simply discarded.

Recycling these wasted food is not new. This idea may be traced back to the first time that early humans thought of eating the less edible part of dinner and using it as a bait. Today, the entire industry revolves around composting or turning restaurant waste into pig manure to feed pigs, and turning bio-waste into fuel or plastic.

The team at the University of Tokyo went further, not only turning food residues such as fruits and vegetables into useful things, but also keeping them in an edible state. The basic idea is to mix ordinary crumbs with seaweed, and then process it into a stronger material than concrete, but still have the taste of the original material.

Researchers used a technology originally developed to make building materials from wood flour to vacuum dry food residues such as seaweed, cabbage leaves, oranges, onions, pumpkins, and banana peels, and then crush them. The powder is then mixed with water and seasonings, and then pressed in a mold at high temperature.

The result is a series of materials, some of which have higher flexural strength than concrete, but are still edible and retain their taste. Although still edible, the material is still resistant to rot, fungi and insects during the four-month test period. Even adding sugar and salt will not affect the strength of the material, although not all fragments have proven to be ideal.

"Except for the specimen from the pumpkin, all materials exceeded our flexural strength targets," said senior collaborator Kota Machida. "We also found that Chinese cabbage leaves are more than three times stronger than concrete and can be mixed with weaker pumpkin-based materials to provide effective reinforcement."

Presumably, the new material is stronger than concrete, but not as hard as anywhere else, otherwise the edibility will be meaningless. Researchers say that these materials have a wide range of "creative applications", but some wonder if it will one day cause the phrase "eating people at home and outside" to be more than just an idiom.

The team’s research will be published in the proceedings of the 70th Annual Meeting of the Japanese Society of Materials Science.