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[The Chemistry of Tears: Why Do Onions Make Us Cry?]-[Hey Onion! You're Makin' Me Cry!]

Wow in the World · B1 · 2017-11-06

Preschool Enlightenment
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📋 Summary

The Science Behind the Onion Sting

In this episode of Wow in the World, hosts Mindy and Guy Raz explore the culinary mystery that has plagued home cooks for generations: why do onions make us cry? Through a mix of humor, scientific curiosity, and a fantastical journey into the microscopic world, the duo breaks down the chemical defense mechanism of the common onion.

The Lacrimatory Factor (LF)

The episode begins with a comedic misunderstanding where Guy Raz is found in tears while chopping onions. Mindy quickly identifies the culprit: the lacrimatory factor, or LF for short. This natural chemical is the primary irritant that causes human eyes to water upon exposure.

Guy Raz explains that the onion, often perceived as just a vegetable, is actually engaging in a sophisticated form of biological warfare. By releasing these fumes, the onion plant creates a "defense system" intended to deter predators—including humans—from eating it. While humans have developed workarounds, such as wearing "flight goggles" or scuba masks to block the fumes, the chemical reaction remains an inescapable part of the onion’s biology.

A Journey Inside the Onion Cell

To understand the mechanism, the hosts embark on a scientific adventure. Utilizing a shrink wand, Mindy enters the microscopic environment of an onion cell. Inside this "aquarium-like" space filled with cytoplasm, she observes the two key components responsible for the reaction:

  1. Sulfenic acid precursors
  2. Alliinase protein bubbles

Under the observation of Guy Raz, who acts as the narrator via microscope, they witness what happens when an onion is sliced. The destruction of the cell wall causes these previously separated components to mix. This interaction creates the chemical reaction that releases the lacrimatory factor (LF) gas. As Mindy describes it, the gas creates a stinging sensation that makes the eyes "tear up in water," effectively proving that the onion is "biting back."

The Trade-off: Flavor vs. Tears

Addressing the possibility of a "tearless onion," the hosts discuss research from Japan where scientists successfully engineered a variety that does not induce crying. However, there is a catch: the same chemical pathway that produces the tear-inducing LF is also responsible for the onion's signature flavor. By removing the irritant, scientists inadvertently removed the "special oniony deliciousness" that makes the vegetable a culinary staple. This reveals a fundamental truth about nature: some of the most pungent and defensive characteristics of plants are inextricably linked to their sensory appeal.

Conclusion

The episode concludes by highlighting that despite the pain and the "stinging eyeballs," the human fascination with the onion persists. Whether it is the chemistry of the reaction or the cultural history of cooking, the onion remains a marvel of nature. The episode serves as a playful reminder that science is happening all around us—even in the simple act of preparing lunch in the kitchen.

🎯Key Sentences

1
I gotta let you know that
2
this one is going to be music to your ears.
3
I'm here to help you get through it
4
Whatever it is, I'm sure it'll pass.
5
I just need to plow through.
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📝Key Phrases

1
music to your ears
2
get on with the show
3
get through it
4
plow through
5
keep to a minimum
Expand All

📖 Transcript

Grownups, Wondery Plus subscribers can listen to Wow in the World early and ad-free right now.
Join Wondery Plus in the Wondery app or Wondery Kids Plus on Apple Podcasts.
Hey, Wowzer fans, Mindy here.
And before we start the show, I gotta let you know that this November, with a special new episode featuring our friends at Circle Round and Terrestrials on Radiolab for Kids,
And don't miss when Elmo from Sesame Street stops by Wow in the World to make us all belly laugh on November 24th.
Oh, but that's not all, Reg.

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