As you could probably tell by spending two minutes in my presence, I love chemistry. It鈥檚 part of who I am. To some people, that might get a little annoying, but I promise I know to tone down the chemistry nerdiness depending on my audience. While learning the technical information is great and all, what really excites me is seeing chemistry in action, especially when it catches me by surprise.
Because I鈥檓 such a chemistry enthusiast, I have made it my mission to convince people that chemistry could be fun (I know, not exactly an easy task). Naturally, this has made me gravitate towards science education initiatives such as the OSS and the 91丝瓜视频 Chemistry Outreach group. Through these experiences I have been able to nurture my love of teaching all while satisfying my overcurious mind. But what I really want to talk about here is a moment that made me fall in love with chemistry all over again.
Love at first light
This past week, I coordinated the Chemistry Outreach Group鈥檚 participation in . Every year this festival brings together organizations from across Montreal to share science with the public through hands-on activities and demonstrations. This year, our group put together an impressive tent featuring demonstrations that showcased materials chemistry at its finest (no bias, of course).
One of these demos involved making body paint, using various extracts of dyes and pigments. Among them was curcumin, the compound responsible for giving turmeric its vibrant yellow colour. To make our paint we added some of this powdered spice to a white face paint base and mixed until smooth. As expected, the curcumin paint would go on the skin a beautiful bright yellow. This obviously prompted all of us demonstrators to decorate ourselves with matching sun-shaped tattoos.
But after a quick walk in the sun, something unexpected happened.
My colleagues went to check out some of the other booths, but when they returned holding out their arms, I was intrigued. I went over to them only to see that their previously yellow tattoos, had turned white. At that moment, this article practically wrote itself.
Getting to know turmeric
We all know turmeric in a kitchen setting. Whether you鈥檙e adding it to enhance the flavour of your curry or even in your ginger 鈥渨ellness鈥� shots, its smell and colour are very familiar. But what we don鈥檛 think of often, is its chemistry.
Curcuminoids are the family of compounds responsible for both turmeric鈥檚 vibrant colour and , the major one being curcumin. Because of their structure, these curcuminoids are potent . Their phenolic rings (those polyphenols Dr. Joe talks about so often) are able to neutralize those nasty free radicals and protect our cells from oxidative stress. Also, there is some that turmeric can be used to manage certain inflammatory conditions, but it鈥檚 not a miracle worker. Anyways, I鈥檓 not here to teach you how to cook or eat, I am here to answer the question: why did our tattoos turn white?
Photodegradation
After looking into this, the answer to my question is relatively simple. Curcumin is UV sensitive. When exposed to the rays of the sun for long periods of time, it starts to degrade by a process known as . As the name suggests, this process refers to a . This change is usually triggered by the combined effects of sunlight and air which can cause compounds to break down. We鈥檙e not talking about a chemical breakdown due to heat; we鈥檙e really talking about degradation throughout the ultraviolet spectrum.
In the case of our turmeric tattoos, exposing them to the sunlight during our walk, triggered photodegradation, causing the curcuminoids to breakdown into smaller phenolic fragments like (the compound responsible for vanilla flavour). This breakdown is responsible for the colour fading. The original structure of curcumin is long and complex and has the ability to absorb blue-violet light, thus reflecting yellow light (by the principle of ). When we disrupt this structure, the molecule can no longer absorb light in the same way, causing the
At this point, you may be wondering what this has to do with your everyday life. As it turns out, understanding turmeric鈥檚 chemistry can be surprisingly useful when it comes to organizing your spice cabinet. You probably already sore it away from direct sunlight, but now you know why.
Love actually is all around
So, there you have it, we unintentionally made colour-changing tattoos, and to me that鈥檚 the wonder of chemistry. The smallest observations can inspire fascinating questions and unexpected lessons. This experience reminded me why I fell in love with chemistry in the first place, and just how interesting the world becomes when you鈥檙e willing to be curious. My friends often say I ask too many questions, I think it鈥檚 part of how we learn. Stay curious.
Angelina Lapalme is a U3 BSc student majoring in Bio-Organic Chemistry at 91丝瓜视频.聽
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