Knife me and you’ll sulfur the consequences.

Volatile compounds. Enzymes. Soil. And how to stop the tears when cutting onions.

oninos1-Minute NomNom

The fresh onion’s pungent aroma and taste can repel some people. Even more bothersome is chopping the onion, every slice bringing more tears to the eyes. Which is a crying shame because onions are layered with antioxidants, especially when eaten raw.

Sulfur is the cause of the waterworks even as sulfur compounds in the onion are responsible for its many health benefits and its odors.Slice of red onion, isolated on white background.Light photomicrograph of an Onion epidermus cells seen through a microscope

Cutting into an onion breaks open the plant cells and starts a chemical chain reaction. Escaped enzymes called lachrymatory-factor synthase react with the amino acid sulfoxides (sulfur compounds) stored in the cells to form sulfenic acids.

These acids are unstable so they rearrange themselves into syn-propanethial-S-oxide, a volatile sulfur gas that wafts up to the eyes and causes a stinging sensation. The lacrimal (tear) glands produce reflex tears to wash away the irritant.goggles on helmetHow can you stop the drama? Wear goggles while chopping the onion to shield your eyes from the tear gas. If you’d rather not look silly in the kitchen, freeze the onion for 15 minutes before chopping. The cold inhibits the enzymes and slows the chemical reactions. Also, start with a sharp knife to minimize damage to the onion cells in the first place.

You can also choose the variety of onions. Regular onions are grown in sulfur-rich soil, which is how they get so pungent. Sweet onions such as the Vidalia variety are grown in low-sulfur soil, so they are milder in taste and cause fewer tears.

Vidalia Onions growing in low sulfur soil


Feed me!

How do you prevent a sob-fest while chopping onions? Share your method in the comments below!


Screen Shot 2015-01-10 at 6.02.39 pmI’ll shed happy tears if you connect with me to discover more. All you need is a minute a day to explore the world’s marvels through the phenomenon of food!


photos: in order – depositphotos/ehaurylikrobynmacclaudiodiviziavladvitekjeep5d

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