2019 is a massive year for celebrations; Fiftieth anniversary of the Moon landing, and the 150th of the Periodic system by Dmitry Mendeleev too. That’s lots of physics, and chemistry to crack away at. I would usually prepare a show that would hit these things but have decided to do something different. After all, it’s only been a couple of years since I produced the ‘Subliming the Ridiculous’ show based on the history of chemistry. So I’ve gone down a more scatalogical route.
One thing unites the fascinations of children and adults, and that is poo. Specifically, the science of food, from plate to poo. We’re going to look at it before and after, while trying to follow the journey between the two as best as possible. But there is one food-based topic we need to talk about which I don’t really want to cover in the show. That is plastic.
2018 has seen an unprecedented focus on single use plastics prevalence in marine life as impact of the second series of Blue Planet. There has been much good said about our overuse of plastics around our food, and I agree with it. However, there needs to be some balance to it, and it lies in the hands of engineers to explain.
The Smallest of Print
Much of the processing of food relies on the use of single use plastics. For instance, a prepared salad will have the words, ‘packaged in a protective atmosphere’ on the packet. This atmosphere is likely 73% nitrogen, 21% oxygen and 5% carbon dioxide, about 100 times the usual amount of that last gas than is usually in our air. This provides nutrients for transpiration of the salad leaves, and also slows the growth of aerobic bacteria, which find the higher carbon dioxide levels quite toxic. It keeps your salad fresher for longer, and needs to be sealed in. Likewise your pre-packed meat, which will be packaged in a protective atmosphere of 100% oxygen which keeps the meat muscle cells from denaturing too quickly. Did you ever notice that oxygenated blood always looks bright red, which deoxygenated blood goes a darker colour? Well the same happens to your meat if it doesn’t get enough oxygen.
Even your organic, ‘Pink Lady’ apples come in a plastic wrapper; but for a good reason. The ripening and the subsequent decay of fruit is caused by the action of polyphenol oxidase, which in apples, is largely near the skin. In order to slow down the action of this enzyme, the skin of the apple is sprayed with citric acid which changes the pH, limiting its effectiveness. The plastic wrapper prevents the removal of this coating and means that your fruit lasts longer, is more resilient to spoilage on its way to your kitchen, and you don’t throw away as much food. Ever wondered why the packaging on your organic apples states it should be washed before eating? Ahh, I’m guessing you didn’t read the packaging. Yet another reason you need it. The clues to the way our modern world is constructed is there, on the packaging.
The message is that we shouldn’t be too quick to wield the axe on things that are engineered to make the most of the goods we produce. Not all single use plastics are for convenience, some serve a valuable function. I’m not saying that we should do nothing. However, I believe engineers could do a better job of communicating how the modern world is constructed and for what purpose. I’m calling for transparency, so that people can decide what they are prepared to forego before we do something we might regret.