Onions have little packets of enzymes inside each cell. These are totally harmless on their own, but when the packet is broken they mix with other things in the cell, which turns them into a gas. The process is pretty similar to when you break the tube inside a glowstick – two formerly boring substances mix together and the reaction glows for hours! Fun, right? The problem is, we break millions of onion cells – and enzyme packets – with one slice of an onion. And instead of glowing, the gas made by those enzymes then reacts with the closest source of water to make sulfuric acid. And usually the closest source of water is our eyes. And sulfuric acid burns like hell, making us cry.
This is a pretty clever defence mechanism if you think about it; if you’re a wild animal looking for a feed and just biting an onion blinds you, no way will you eat one again. But cooking makes it all harmless again, and delicious! Yay! However, that still leaves us with the problem of chopping the raw onions in the first place. Don’t worry guys, we’ve got your back!
1) Put that onion in the fridge. If you did high school chemistry, or tried to get out of bed on a chilly Dunedin morning, you’ll know that reactions are slowed down by the cold. This won’t stop the tears, but less gas will be produced so you won’t cry like a little bitch quite as much.
2) Put water everywhere – if your chopping board, knife, onion and cheeks are damp, the nearest water will be there and not your eyes! Woohoo! The sulfuric acid will still be made but it’s a tiny amount that can’t do any damage unless you then put it on a sensitive membraneous surface. And by that, I mean your eyes. Seriously, don’t.
3) If you’re that desperate, just wear some bloody ski goggles. You’ll look pretty damn silly, but it works.
Suck it, onions – that’s science, bitches.
P.S. We were going to write this column about vitamins and minerals, but onions were way cooler. Basically, eat your greens (and other colourful veges) and you won’t get scurvy/rickets/night blindness. And if you’re feeling tired, get your iron levels checked.
Science, Bitches! is written by members of the Science Community of Otago (SciCo).