Have you ever wondered why slicing into an onion can turn even the toughest cook into a blubbering mess? It’s a common kitchen conundrum, but the science behind those tears is surprisingly fascinating!
Onions, you see, are part of the Allium family, just like garlic and chives. They’re pretty good at absorbing sulfur from the soil, and they store it in compounds within their cells.
Now, here’s where the magic, or rather, the chemistry, happens! When you cut an onion, you’re actually breaking open its cells. This releases previously separated enzymes, like alliinase, and sulfur-rich amino acids.
These enzymes and sulfur compounds then mix and react to form unstable sulfenic acids. But they don’t stop there! Another enzyme, called lachrymatory factor synthase, quickly rearranges these sulfenic acids into a tricky little chemical called syn-propanethial S-oxide.
This syn-propanethial S-oxide is a volatile gas, meaning it easily evaporates and floats into the air. And guess what? It loves to make a beeline for your eyes!
When this gas comes into contact with the watery surface of your eyeballs, it reacts, forming a mild sulfuric acid. Yes, you heard that right – a tiny bit of acid in your eyes!
Your eyes, being the sensitive organs they are, quickly detect this irritant. In a desperate attempt to protect themselves and wash away the offending chemical, your brain sends a signal to your tear glands, triggering a flood of tears! It’s basically your body’s built-in defense mechanism against this botanical “tear gas.”
So, while it feels like the onion is out to get you, it’s actually just protecting itself! Some onion varieties, like sweet onions, have less of these tear-inducing compounds, which is why they might make you cry less.
Now you know the teary truth behind onions! Understanding this chemical reaction can even help you reduce the tears next time you’re in the kitchen.