Nature’s Packaging: Building Cutlery Without Plastic
Single-use plastic cutlery is one of the everyday items that has proved difficult to replace; it is cheap, lightweight, and produced at an enormous scale. But as pressure mounts to move away from fossil-based plastics, finding a material that can do the same job without the environmental impact is becoming increasingly important. And at this point, most can admit, paper straws can’t do all the heavy lifting.
As part of InnoProtein’s ongoing work on bio-based applications, research partners at AIMPLAS have been doing exactly that: developing a fully plastic-free material made from chitin and starch, with disposable cutlery in mind.
Finding the right recipe
Chitin is an incredibly abundant organic material sourced from shells of crustaceans, such as the insect cultivated in earlier InnoProtein research[1]. When combined with starch, it forms the basis of a material that is fully bio-based and biodegradable. However, the challenge is that in their natural form, neither material behaves anything like plastic.
To be shaped using standard manufacturing equipment, they need to be transformed into something that softens when heated, and that requires a plasticizer. In this case, that’s glycerin, with small amounts of citric acid and wax added to help the ingredients work better together. Getting the balance right took considerable trial and error. Too much chitin and too little glycerin, and the mixture stays powdery and crumbly rather than forming a smooth, pliable melt. Turning up the heat to compensate just caused the material to break down. The breakthrough came from finding the right proportions: enough glycerin to properly soften the mixture, a moderate amount of chitin, and the additives doing their part. Three formulations came out of this phase as strong candidates.
Scaling up
The two most promising formulations were then run through an extruder (a machine that works a bit like a high-powered pasta maker) using rotating screws to continuously mix, heat, and push the material into a consistent shape. Both performed well, with steady output and good quality.
One early issue was small bubbles forming in the material as moisture escaped under heat, but opening a vent on the extruder drew those gases out and solved the problem. A third formulation with higher chitin content was attempted, too, but the process became unstable, and it was set aside.
From pellets to plates
The extruded material was then shaped into flat plates using a hot press, applying controlled heat and gradually increasing pressure to produce uniform, solid sheets. These plates will be cut into smaller pieces and physically tested to see how the material holds up under stress, the same way any material destined for real-world use would be evaluated.
If the material is strong and stable enough, the best-performing formulation will be scaled up and run through injection molding, the process used to manufacture actual cutlery shapes. That will be the real-world proof of concept: a fork or spoon made entirely from natural, biodegradable materials, produced using the same kind of equipment already used for conventional plastic cutlery.
References
[1] Muxika, A., Etxabide, A., Uranga, J., Guerrero, P., & De La Caba, K. (2017). Chitosan as a
bioactive polymer: Processing, properties and applications. International Journal of
Biological Macromolecules, 105(Pt 2), 1358–
