Researchers turn food waste into robust construction materials

A research team at the Institute of Industrial Science (IIS) at the University of Tokyo, Japan, has developed a method to reduce food waste by recycling discarded fruit and vegetable scraps into robust construction materials.

Worldwide industrial and household food waste amounts to hundreds of billions of pounds per year, a large proportion of which comprises edible scraps, like fruit and vegetable peels. This unsustainable practice is both costly and environmentally unfriendly, so researchers have been searching for new ways to recycle these organic materials into useful 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, the senior author of the study and associate professor at IIS,  the University of Tokyo. “But since we were using edible food waste, we were also interested in determining whether the recycling process impacted the flavour of the original materials.”

In its statement, the university explained that the researchers borrowed a ‘heat pressing’ concept that is typically used to make construction materials from wood powder, except they used vacuum-dried, pulverised food scraps, such as seaweed, cabbage leaves, and orange, onion, pumpkin, and banana peels as the constituent powders.

The processing technique involved mixing the food powder with water and seasonings, and then pressing the mixture into a mould at high temperature. The researchers tested the bending strength of the resulting materials and monitored their taste, smell and appearance.

“With the exception of the specimen derived from pumpkin, all of the materials exceeded our bending strength target,” said 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.”

The new, robust materials retained their edible nature, and the addition of salt or sugar improved their taste without reducing their strength, according to the university. Furthermore, the durable products resisted rot, fungi and insects, and experienced no appreciable changes in appearance or taste after exposure to air for four months.

The university emphasised that it is crucial to develop methods for recycling food scraps, given that food waste is a global financial burden and environmental concern. “Using these substances to prepare materials that are strong enough for construction projects, but also maintain their edible nature and taste, opens the door to a wide range of creative applications from the one technology.”

This innovative method will be published in the proceedings of the 70th annual meeting of the Society of Materials Science, Japan as ‘Development of Novel Construction Material from Food Waste.’

Photo: Institute of Industrial Science, The University of Tokyo