English 箭头
Podcast Cover

[The Chemistry of Tears: Why Do Onions Make Us Cry?]-[Hey Onion! You're Makin' Me Cry! (Encore - 10/14/19)]

Wow in the World · B1 · 2019-10-14

Preschool Enlightenment
Or study on the web version

📋 Summary

The Science Behind the Onion-Induced Tears

In this episode of Wow in the World, hosts Mindy and Guy Raz delve into the common, yet often painful, culinary experience of chopping onions. What begins as a comedic misunderstanding—Guy Raz appearing to sob over his lunch preparation—transforms into an educational exploration of plant defense mechanisms and chemical reactions.

The Lacrimatory Factor (LF)

Guy Raz initially attributes his tears to the act of chopping onions, a phenomenon many listeners will find relatable. Mindy identifies the culprit as a specific chemical known as the "lacrimatory factor," or "LF" for short. This chemical is responsible for the stinging sensation in the eyes and the subsequent production of tears. As the hosts explain, this is not merely a biological accident; it is a sophisticated "defense system" that the onion plant has evolved to deter pests and predators from consuming it.

Inside the Onion Cell: A Microscopic View

To understand the chemistry in action, the hosts utilize a metaphorical (and humorous) shrinking scenario to observe the interior of an onion cell. Inside the cell, they identify two key components that remain separated until the onion is damaged:

  1. Sulfenic acid precursors: These float within the cell's cytoplasm.
  2. Alliinase: A protein stored in separate bubbles within the cell.

When a knife slices through the onion, these components are released and mix together. This reaction creates a gas that, upon reaching our eyes, triggers the formation of the lacrimatory factor. The hosts describe this as witnessing a "true chemical reaction in nature," where the onion essentially "bites back" when it is cut into.

The Trade-off: Flavor vs. Tears

The episode also touches upon modern scientific attempts to engineer a solution. Mindy mentions that scientists in Japan have successfully developed a "tearless onion." However, there is a significant culinary trade-off: the very chemical responsible for the lacrimatory factor is also linked to the onion's distinct flavor profile. By removing the chemical that causes tears, scientists inadvertently removed the substance that gives onions their "special oniony deliciousness." Consequently, the hosts conclude that for the time being, home cooks must accept the tears as an unavoidable part of preparing their favorite dishes.

Practical Tips and Conclusions

Throughout the discussion, the hosts offer lighthearted but scientifically grounded advice for minimizing the irritation caused by onions. Guy Raz notes that wearing "flight goggles" or scuba masks can effectively block the onion fumes from reaching the eyes. They also provide a necessary "public service announcement," reminding younger listeners that any kitchen experiments should only be conducted under the supervision of a grown-up, as cutting onions can lead to "runny nose" and "temporary loss of friends" due to the pungent smell.

Ultimately, this episode highlights how even the most mundane kitchen tasks are governed by fascinating chemical processes, reminding us that nature's defenses are often the very things that provide the complex flavors we enjoy in our food.

🎯Key Sentences

1
I'm sure it'll pass.
2
I just need to plow through.
3
I'm coming over.
4
Sounds like you need a hug.
5
Why are you so sad, anyway?
Expand All

📝Key Phrases

1
music to your ears
2
get on with the show
3
help you 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.

ListenLeap Brings You Into Real Context Learning

🎨 Interesting Content
🌍 Real Materials
📱 Listen Anytime
Or study on the web version