Whether or not sautéed, grilled, caramelized or uncooked, onions are a staple in lots of U.S. households; the common American consumes 20 kilos (9 kilograms) of onions per 12 months. However their coveted taste comes at a worth: Whoever chops them might quickly really feel tears working from their burning eyes. However why does slicing onions make you cry?
The perpetrator is known as the lachrymatory issue, a chemical that irritates the eyes. When the onion is unbroken, a gaggle of compounds known as cysteine sulfoxides are saved separate from an enzyme known as alliinase. However while you slice, cube or crush the onion, the barrier separating the compounds and enzyme is damaged. The 2 come collectively, setting off a response: The alliinase causes the cysteine sulfoxides to develop into sulfenic acid.
“Sulfenic acids will not be very steady,” so they need to grow to be one thing else, mentioned Josie Silvaroli, a health care provider of pharmacy doctoral candidate at The Ohio State College and first writer of a 2017 examine within the American Chemical Society’s journal ACS Chemical Biology concerning the lachrymatory issue. In an onion, the sulfenic acid has two choices. Choice one is that it could spontaneously condense, a response inside itself, and develop into an organosulfur compound. Organosulfur compounds are what give onions their sturdy scent and taste. An analogous response occurs in garlic, which is why it additionally has such a pungent taste, Silvaroli mentioned.
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However choice two for the sulfenic acid is exclusive to onions and a pair different alliums, or a genus of flowering vegetation that produce greens reminiscent of onions, garlic, scallions and shallots. One other enzyme, known as lachrymatory issue synthase, that is been hiding out within the cell comes into play and rearranges sulfenic acid into the lachrymatory issue.
The lachrymatory issue is a unstable liquid, that means it turns to vapor in a short time, Silvaroli mentioned. That is the way it reaches your eyes and irritates sensory nerves. “Your eyes begin tearing as much as eliminate the irritant,” Silvaroli informed Dwell Science.
It is doubtless that each the organosulfur compounds that give onions their intense taste and the tear-inducing lachrymatory issue advanced as protection mechanisms, Silvaroli mentioned. They’re meant to cease bugs, animals or parasites which may injury the onion plant.
If burning tears are greater than you may bear, you do have choices. Bon Appetit recommends you put on goggles or a face protect to guard your eyes. (Contact lenses additionally provide a barrier towards lachrymatory issue.) Utilizing a pointy knife, which damages fewer cells and creates much less “tear fuel” than a uninteresting knife, can also assist.
There are additionally efforts to create tear-free (or at the very least fewer-tear) onions. The Sunion, whose cultivators describe it as “candy and delicate,” was developed utilizing crossbreeding strategies to be much less pungent. However Silvaroli is cautious; as a result of the compounds liable for lachrymatory issue are the identical flavorful organosulfur compounds that give onions their distinct style, lowering the cry issue might additionally uninteresting the onion’s taste. For now, Silvaroli mentioned, “If you’d like that taste, you would possibly must endure by means of some burning.”
Initially printed on Dwell Science.