Most of us dread cooking with onions. For many Indian recipes, the first step involves chopping raw onions which means that the next few steps are usually accomplished with blurry eyesight. We hate how it stings us with tears of irritation and leaves some of us sobbing uncontrollably. If you’re not aware, we’ll give you the answer to the age-old question. Why do onions make you cry and more importantly, how do you make it stop?
First, the science. When you slice an onion, you break through its cells. This releases certain sulfenic acids that react with the other enzymes that are now free. The chemical reaction between the two creates a volatile sulphur gas (propanethiol S-oxide) that wafts upwards towards your eyes. The gas mingles with the water present in the tear glands of your eyes to produce sulphuric acid. It’s the sulphuric acid that causes the burning sensation which stimulates your eyes to form more tears in order to wash away the irritant. Phew!
These sulphur compounds are also responsible for leaving the unwanted odour on your fingers and hands while chopping. When you cook the onion, these enzymes become inactive and so they don’t burn your eyes. And now for the part that you’ve been eagerly waiting for. Seven effective ways of chopping onions without tearing up:
1. Cut the onions near a vent or under a fan that blows the gas away from your eyes. It works, as long as you have a good overhead vent.
2. Refrigerate your onions for about 15 minutes before cutting them. This slows down the reaction and changes the chemistry of the chemicals inside the onion. Extreme temperatures inhibit the release of chemicals that irritate your eyes. Avoid freezing, as frozen onions may turn mushy when thawed.
3. Use a sharp knife. It works! By using a sharp knife you cause less damage to onion cells and thus, fewer irritants will be released.
4. It is believed that the root contains a higher concentration of enzymes and sulphuric compounds, so cut them off before you begin chopping.
5. Martha Stewart suggests that you should slice onions close to an open flame. You can use the flame of a candle or right next to a high flame of your gas stove. The sulphur from the flame disables the compounds in onions.
6. Cut off the tops of the onion and soak it in water for about 15-20 minutes. This is known to draw out the sulfuric compounds from the onion into the water. But some argue that this may also lessen the strong flavour of onions. This also makes the onion a bit slippery, so be careful while cutting.
7. Cut like a pro. Some chefs suggest the right way to cut onions, where the exposed area faces the chopping board and this prevents the gas from coming in contact with your eyes. Watch the following video to learn.