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Tearless onions

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I’m a sensitive kinda guy. I fact, I’m so sensitive I sometimes tear up just during the process of making dinner.

It’s not that I’m overcome with emotion at the blessing of having at my disposal the wherewithal to stir-fry. (I’m not that sensitive.) No, it’s usually because I’m slicing onions.

Onions have been a part of the human diet since prehistoric times. We don’t even know where they originated: some say central Asia, others Iran or West Pakistan. (So I learned from the interesting history of onions I found on the website of the U.S.’s National Onion Association, an organization whose very existence had heretofore escaped me.)

Once humans started farming, onions may have been one of their very first crops. They’re less perishable than many, can be easily transported, and will grow in a variety of soils and climates. They’re full of water, so they help prevent thirst, but they can also be dried and stored for eating later when food is scarce.

Chinese gardens had onions 5,000 years ago. The Egyptians, for whom the onion symbolized eternity, buried them with their Pharaohs and frequently depicted them in religious imagery. Onions are mentioned in the Bible The ancient Greeks fed onions to athletes to fortify them for the Olympic Games.

Onions were a staple in the Middle Ages in Europe, and the first Europeans brought onions with them to North America—only to discover the First Nations people were already using onions in a variety of ways.

But for all those thousands of years, onions made people cry once they were sliced open. The reason: when you break open the cells of an onion, you release enzymes that decompose some of the other substances that escape from the broken cells, forming sulfenic acids which escape the onion as a volatile gas.

This gas reacts with the water on your eyes to form, among other things, a mild sulfuric acid—very irritating, as you’d expect. When your eyes are irritated, they produce extra tears in an attempt to dilute or wash away the irritating substance. (A process we contact-lens wearers are particularly familiar with.)

But your teary-eyed onion-cutting days may soon be over, for recently in The Netherlands, at the Fifth International Symposium on Edible Alliaceae (Super Bowl, Schmuper Bowl—what an event that must have been!) Dr. Colin Eady of The New Zealand Institute for Crop & Food Research (one of their Crown corporations) announced that he and his Japanese collaborators have been successfully produced and tested tearless onions in the laboratory.

How do you take the tears out of an onion? By silencing the lachrymatory factor synthase gene, which tells the onion’s cells to turn sulfur compounds into the chemical that decomposes into the sulfenic acids that causes your eyes to sting. With that gene silenced, the sulfur compounds that would normally go into that chemical are instead available for the onion to turn into other compounds that contribute to the flavor and health benefits the onion provides.

Better yet, the gene silencing technology does not involve genetic engineering as it is usually thought of: no genes are introduced from other species, so no proteins show up in the onions that aren’t already present in onions. It’s a process of subtraction, rather than addition.

The announcement hit the onion world like a bombshell. Dr. Eady’s work was featured on the front cover of Onion World magazine’s final issue of 2007. The magazine quoted renowned onion scientist Dr. Michael J. Havey, a professor of horticulture at the University of Wisconsin, as saying that Dr. Eady’s work was the number one topic of discussion at the symposium in The Netherlands. Dr. Havey predicts that tearless onions will eventually become a mainstay in kitchens around the world.

When you cut an onion and your eyes well up, you are part of a great unbroken link of weepy-eyed onion-cutters dating back through millennia to before the dawn of civilization. It’s astonishing to think that, if this research pans out, that link may soon be severed.

But you know what? Sensitive though I am, I won’t shed a tear over it.

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    • Edward Willett on February 7, 2008 at 6:22 pm
    • Reply

    If I understand them correctly, they seem to be saying this might actually increase the flavor, because the sulphur compounds that would otherwise be wasted on sulfenic acids to make your eyes sting will be available to be developed into flavor compounds.

    • Ian H. on February 5, 2008 at 9:36 pm
    • Reply

    The question is, did they manage to maintain the taste of the onion? it’s all well and good to get rid of the tears, but if there is a commensurate decrease in the taste, then it’s all for naught.

    • Janet on February 4, 2008 at 9:50 pm
    • Reply

    Will you shed a tear if I tell you I tagged you?

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