Recently, Saitama Institute of Technology in Japan developed a technology to produce and mold bio-plastics using discarded leaves from locally grown *Fukaya* scallions. This bio-plastic exhibits processing characteristics similar to conventional plastics and holds great promise for a wide range of applications.
The university is located in Fukaya City, Saitama Prefecture-a major production hub for the renowned "Fukaya scallion," with an annual output of approximately 30,000 tons. To meet shipping standards for cardboard packaging, the long green tops of the scallions must be trimmed before shipment, generating about 6,300 tons of agricultural waste annually. Most of these trimmed leaves are buried directly in the fields; however, because they contain sulfur compounds such as allyl sulfides, they emit a strong, unpleasant odor as they decompose. This has long been a pressing issue for local farmers. Previous attempts to use the waste leaves as fuel for smoking foods proved ineffective and failed to gain traction.
A research team led by Professor Teruhisa Hongo focused on the cellulose content within the scallion leaves. Analysis revealed that dried leaves contain up to 28% cellulose. The team soaked fresh waste leaves in an alkaline solution to remove hemicellulose and some lignin, followed by bleaching to eliminate remaining lignin. This process yielded high-purity, white, insoluble cellulose fibers free from any scallion odor. These extracted fibers were processed by a partner company into composite resin pellets consisting of 55% scallion-derived cellulose and 45% polypropylene. The resulting pellets are brownish-tan, odorless, and stable for long-term storage without degradation. The technology enables an annual production of approximately 350 tons of these resin pellets. Additionally, the process incorporates composting for the remaining agricultural waste; this approach achieves superior CO2 reduction compared to simple incineration, cutting emissions by more than half relative to incineration.
The material is compatible with standard injection molding processes: the resin pellets are heated to approximately 190°C and injected into molds to create various products. The research team has produced prototype chopstick rests shaped like Japanese bunching onions and developed a unique Othello (Reversi) set. The game pieces are made from onion-based plastic-featuring one white side and one soft dark-green side-while the board is crafted from recycled local rice husks. This Othello set has attracted the attention of the Fukaya municipal government, with plans to include it in the list of return gifts for the "Hometown Tax Donation" program in the 2026 fiscal year; a product launch event held in November 2025 was attended by the Mayor of Fukaya.
This initiative is a collaborative regional revitalization project involving industry, government, and academia. Its primary objective is to transform waste into valuable resources, thereby channeling profits back to farmers and improving their financial well-being. Beyond bunching onions, the team is exploring upcycling other agricultural waste-such as creating black tableware from green plum pits and producing activated carbon from pruned plum tree branches-and is investigating ways to utilize discarded broccoli leaves. These efforts aim to continuously convert agricultural waste into high-value-added products, embodying the principles of a circular economy.
