Dude, are you crying?

As our journey here in Siena comes to an end, we say our goodbyes to new friends, wondering if we will ever see them again or come back to this beautiful city. After saying goodbye to some of our closest Italian friends, Angelo and Paolo, I started wondering if there was any chemistry behind the act of crying. Being a guy, of course I have never shed a tear in my life, except in the movie Click, which was an unbelievably sad movie. Though I could find little information about the emotional act of crying, I did come across why onions make people cry, which I also found interesting. After eating an entire onion for fun at one point in my life, I have been somewhat curious about this vegetable.
Everyone knows that cutting up onions will make your eyes burn a bit and tear up. When you cut an onion, you break cells, releasing their contents of amino acid sulfoxides. Enzymes mix with these acids to form propanethiol that float to your eyes. This reacts with the water in your eyes to form sulfuric acid; this irritates your eyes, causing your eyes to release tears to wash it away. Cooking onions inactivates the enzyme, so the smell of cooked onions do not burn your eyes. If your eyes really irritate you when you are trying to chop up onions, you can try refrigerating onions before cutting them, as the cooler temperature will slow down the reaction, or cutting the onion underwater.
Also, I had a great time in Siena with all of you. I wish nothing but the best for everyone’s future. If anyone wants to have a glass of wine with me back in the states, give me a ring and I’ll try my best to come, after all, I do like to party.

http://chemistry.about.com/od/chemistryfaqs/f/onionscry.htm