Refrigerating Onions Cuts Tears, Food Writers Say
Chilling onions for one to two hours before chopping reduces the potency of the tear-inducing enzyme alliinase, according to food science experts.
Refrigerating onions for an hour or two before chopping them can significantly reduce the vegetable's notorious tear-inducing effect. This simple technique works by slowing down the enzyme responsible for producing the irritating sulfur compounds, according to food science explanations from experts including Harold McGee and Nik Sharma.
Why Onions Make You Cry
When an onion's cells are damaged by cutting, they release an enzyme called alliinase. This enzyme produces volatile sulfur compounds. In his book On Food and Cooking, food science writer Harold McGee explains that this is a defensive mechanism. Plants, being immobile, produce strong-tasting or irritating chemical signals to deter predators. For onions, these sulfur compounds are meant to annoy and repel attackers by irritating their eyes, nose, and mouth.
The potency of these compounds is directly linked to temperature. The chemical reactions driven by the alliinase enzyme are most active in warmth.
The Chilling Solution
Cookbook author and Serious Eats contributor Nik Sharma offers a direct solution based on this science. In his cookbook Veg-Table, he writes that alliinase "produces its most potent chemicals at warmer temperatures; cold temperatures will reduce the activity of this enzyme." His recommended method is straightforward: simply refrigerate whole onions for one to two hours before you need to slice or dice them.
The cold temperature slows the enzyme's activity, resulting in fewer of the irritating compounds being released into the air when the onion is cut. This method targets the root cause of the problem rather than attempting to block the compounds after they are airborne.
Anecdotal Success
A writer for Serious Eats tested Sharma's method after reading about it in Veg-Table, which was released in 2023. They refrigerated an onion for an hour before slicing it. The result was a tear-free chopping experience. The writer acknowledges this is an anecdotal, personal test and not a rigorous scientific comparison to other techniques. However, based on that experience, they report becoming a "converted believer" in the pre-chill method.
While individual results may vary, the technique is supported by the underlying food science principle that enzyme activity diminishes in the cold. For cooks tired of weeping over their cutting boards, this low-effort trick offers a promising way to minimize kitchen tears.
