New plastic alternative made from peas

Spider silk has inspired scientists to make transparent film from peas that could replace single use plastics
22 June 2021

Interview with 

Marc Rodriguez, Xampla


Plastic in the ocean


We all use plastic every day, and a lot of it regrettably ends up contaminating the environment, where it doesn’t break down. Now a Cambridge University spin-out company called Xampla may have found a possible solution with a biodegradable plastic film made from peas.

Sally - Plastic films are everywhere. Just looking around my kitchen right now. I've got it around bread, tomatoes, cereal. Plastic is strong and flexible, and it's very durable, which is great if you need it to last for decades, but I don't really need my cereal bag to last for decades. And if it ends up in the environment, it's not going to biodegrade. But what if an alternative to plastic film was also tucked away in my kitchen in this. A bag of peas.

Marc - We just take pea protein, a little bit of concentrated vinegar and a little bit of heat and energy. And essentially just by combining all those things produces our material, which is a very strong, flexible, and transparent material that can be used as a single use plastic replacement.

Sally - That's Marc Rodriguez from Cambridge spin-out company Xampla talking about a new material they've invented, a biodegradable film made from peas.

Marc - If I was giving you a tiny piece of this film, you couldn't really tell the difference with plastic other than that it feels a little bit softer. And sometimes it's a bit more brown in color that it's not completely clear, but other than that, it almost completely, looks like plastic.

Sally - The Cambridge team got their inspiration from spider silk. Gram for gram silk is stronger than steel and is made almost entirely from protein. The protein molecules in the silk are all packed tightly together, which is what allows it to be so strong while also being flexible. But rather than try to use silk proteins to make their plastic alternative, the researchers realise that they could use pea proteins instead, which being plant-based, are much cheaper and more readily available. They were able to do this because all proteins have a very similar underlying chemical structure. So with the right manipulation, you can make a pea protein look very similar to silk protein.

Marc - Fundamentally, you could take any protein and generate these structures that you find in silk.

Sally - And because it has the same properties as spider silk, that also means it biodegrades.

Marc - You can think of it as if it was like a food waste. We are taking something that already exists in nature and putting it back.

Sally - But if a material biodegrades too readily, it will start rotting on the shelves before you've even finished using it. So I asked Marc what stops that from happening?

Marc - The really good thing about plant proteins is that they're very insoluble. So that will provide them with a lot more stability specifically when there's like a very humid environment, for example. But at the same time, they can still break down in the presence of microorganisms and enzymes. So that essentially enables you to have very good shelf life. But then when that material ends up in the environment where there's a lot more microorganisms and bacteria to start breaking it down, it will then break down completely.

Sally - There have been quite a few biodegradable plant-based plastics around, like cellophane has been around for literally a hundred years. So what makes this material better?

Marc - It's not one material that's going to solve all the plastics problem. And actually cellophane is a great material itself. The problem with cellophane is it probably requires very like aggressive chemicals to be able to process it. Traditionally, cellophane manufacturers use carbon disulfide, which is a very polluting chemical. When you think about trying to find the right materials to replace plastics, you don't have to think only about the end of life or its biodegradation. You also need to look at the raw materials, how those raw materials are processed and whether the entire process to make that material is actually sustainable.

Sally - What are your plans for this material?

Marc - Lots of plans at the moment, and it's not just the single use plastic problem we're trying to solve. It's also the microplastic, because there's lots of small particles, a small microplastics that are added to a lot of consumer products. So just as an example, fabric softeners, a lot of fabric softener, if not the majority of them, have tiny microplastic particles. And that's to provide specific function when it comes to release fragrance. So one of the main areas we're working on is specifically that area, which is replacing microplastics in a lot of consumer products.

Sally - And how long is that going to take?

Marc - We are expecting that next year, we will launch our first product specifically on the microplastic replacement, but we already working on generating these transparent films that can replace single use plastics and things like sachets, for example.


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