Sustainable Indicators Based on Furfural-Derived Colorant-Doped Biobased Polyurethane to Improve Food Safety

Ensuring food safety is a never-ending challenge. Developing time–temperature indicators (TTIs) having biobased temperature-responsive colorants (TCs) is an effective method for improving food safety. However, these colorants still suffer from limitations, including difficulty in scaling up for industrial production, imposing pressure on edible resources, and poor thermal stability, which seriously impedes their wide use in TTIs. Here, a new generation of biobased TCs based on furfural, featuring high yield, color tunability, reversible color change, and high thermal stability, are demonstrated. After doping them into a plant oil-based polyurethane, the resulting biobased film and corresponding TTI enable us to monitor the thermal history of food stored in the refrigerator precisely and improve food safety before consuming by visual color change. In addition to high biocontent, lightweight, and flexibility, the designed TTIs possess color tunability, durability, reusability, waterproofing ability, and cost efficiency, thus providing a significant step closer to their wide use and sustainability. This work represents an important complement to modern food packaging technology for improving food safety.