Tikka, tikka, tikka… Boom! On March 24, just as this issue was beginning to develop, our news desk sprang to life as researchers in the US announced that turmeric could detect explosives. We’ve always known spices had a lot to give, but this takes our cherished ingredient to a whole new level. We called up Chaat’s science expert Mark Frary to find out just how this works… Turmeric has long been revered for its health benefits, yet new research shows that it may have uses beyond both the kitchen and the hospital; scientists at the University of Massachusetts in Lowell have shown how the active ingredient in turmeric can be used to detect explosives such as TNT! Professor Jayant Kumar, Dr Mukesh Pandey and Abhishek Kumar revealed in a presentation to the prestigious American Physical Society how the optical properties of curcumin, the active ingredient in turmeric, could be used to detect inute traces of explosives in the air. The technique relies on something called fluorescence spectroscopy which is closely linked to why objects look the colour they do.
Colour Me Baad
Imagine a red balloon. White light, which is made up of a mixture of different colours of light, from a light bulb or the sun lands on the balloon. The reason we see the balloon as red is that the colours other than red are absorbed by the balloon and then re-emitted in every different direction, reducing the intensity of those colours in the direction of viewing. The red light is not absorbed and is simply reflected into our eye. Brightly coloured turmeric, meanwhile, absorbs blue light and reflects the remaining red and green components, which combined to form the yellow we recognise and love. Every different substance or object absorbs a different cocktail of light. The researchers use this, and the fact that curcumin binds together easily with molecules of TNT, to detect those minute traces. Here’s how… Say you were passing through an airport carrying a bag that previously contained a bomb. The security officer could take a sample of the air in the bag and introduce it into a detector containing a thin piece of film coated in curcumin. The film is coated with a sea of nanofibres, giving it a high surface area – important when you are trying to detect the small concentrations of substance involved. When the air passes through this ‘hairy’ film, some of the curcumin embedded in it grabs hold of an explosive particle. Now, when a trong light is shone on the film something strange happens. If there is nothing in the air, then the curcumin-coated film glows brightly. However, curcumin that has reacted with TNT absorbs much more of the light falling on it and the film turns black. You are promptly arrested. “Explosives like TNT and PETN are very hard to detect because [there are] typically only a few molecules per billion air molecules at room temperature,” explains Kumar. The minute traces of material involved mean that an airport security official or the kitchen table amateur scientists couldn’t achieve the same effect with a tub of curry powder. Yet it is amazing to think that the bright colour that we curse when we get it on our pristine white clothes and tablecloths is actually a boon in the war on terrorism. The team’s sensor is so sensitive it can detect less than a trillionth of a gramme of explosive. By tweaking that is used on the special film, the detector can be used to seek traces of toxic gases in mines, at factories and accident sites. So here’s to turmeric; the spice that keeps on giving.