You cry when you cut garlic due to a chemical reaction that irritates your eyes, stimulating tear production.
Here's a breakdown of what happens:
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The Culprit: Allicin Formation: When you cut or crush garlic, you break open its cells. This releases an enzyme called alliinase.
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Chemical Reaction: Alliinase converts alliin, a naturally occurring compound in garlic, into allicin. Allicin is what gives garlic its pungent smell and flavor.
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Further Transformation: Allicin is unstable and quickly breaks down into other sulfur-containing compounds, including propanethial S-oxide.
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Eye Irritation: Propanethial S-oxide is volatile, meaning it easily evaporates and becomes airborne. When it reaches your eyes, it reacts with the moisture to form a mild form of sulfuric acid.
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Tear Production: This mild acid irritates the nerves in your eyes, triggering your tear glands to produce tears in an attempt to wash away the irritant. It's a natural defense mechanism.
In summary, the process looks like this:
Garlic Cells Broken --> Alliinase Released --> Alliin converted to Allicin --> Allicin breaks down into Propanethial S-oxide --> Propanethial S-oxide irritates eyes --> Tear production.
Tips to Reduce Tearing:
While you can't completely eliminate the reaction, you can minimize the irritation:
- Chill the Garlic: Refrigerating garlic can slow down the enzymatic reaction.
- Use a Sharp Knife: A sharp knife causes cleaner cuts, reducing cell damage and the release of enzymes.
- Work Near Ventilation: Cutting garlic near a fan or open window helps to dissipate the irritating compounds before they reach your eyes.
- Wear Goggles: While not the most stylish solution, goggles provide a physical barrier to protect your eyes.
- Consider Pre-Minced Garlic: Though not as flavorful, using pre-minced garlic eliminates the need to cut it yourself.
The same compounds that make you cry when cutting garlic are also present, though often in smaller quantities, in onions and spring onions, which is why you might experience a similar reaction when preparing them. The irritation to the tear glands causes it to secrete tears continuously, independent of any emotional state.
