It sounds like the premise of a comedy sketch, but researchers at the Institute of Industrial Science at the University of Tokyo led by Yuya Sakai have developed a way to recycle food scraps into construction materials that are stronger than concrete, yet remain edible and tasty.
According to the United Nations, 1.3 billion tonnes of food is wasted worldwide every year. Some of this is lost due to inefficiencies in the food chain, but large amounts are also wasted because the produce is deemed to be substandard or past its sell-by date, or because scraps and leftovers are simply discarded.
Recycling such wasted food isn't new. The idea probably dates back to when early humans first hit upon the idea of taking the less edible bits of dinner and using it as bait. Today, there are whole industries that revolve around things like composting or turning restaurant waste into slops for feeding pigs, as well as converting biowaste into fuel or plastics.
The University of Tokyo team is taking things a step further by not only turning food scraps like fruits and vegetables into something useful, but also keeping them in an edible form. The basic idea is to take common scraps, mix them with seaweed, and then process it to produce materials that are stronger than concrete, but still tastes like the original material.
Using a technique originally developed to make building materials from wood powder, the researchers took food scraps including seaweed, cabbage leaves, orange, onion, pumpkin and banana peels, and vacuum-dried and then pulverized them. The powders were then mixed with water and seasonings, then pressed in a mold at high temperature.
The results were a range of materials, some of which had a higher bending strength than concrete, yet remained edible and retained their taste. Despite remaining edible, the material resisted rot, fungi, and insects for a test period of four months. Even adding sugar and salt did not affect a material's strength, though not all scraps proved to be ideal.
"With the exception of the specimen derived from pumpkin, all of the materials exceeded our bending strength target," says Kota Machida, a senior collaborator. "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."
Presumably, the new materials are stronger than concrete, but not anywhere near as hard, otherwise the edibility would be moot. The researchers say that the materials have a wide range of "creative applications," but one wonders if it could also one day lead to the phrase "eating someone out of house and home" being more than just an idiom.
The teams's research will be published in the proceedings of The 70th Annual Meeting of The Society of Materials Science, Japan.
Source: University of Tokyo