why do onions make your eyes water

Why
does chopping an onion make you cry? Unstable
chemicals. Onions produce the chemical irritant known as syn-propanethial-S-oxide. It stimulates the eyes' lachrymal glands so they release tears. Scientists used to blame the enzyme allinase
for the instability of substances in
a cut onion. Recent studies from
Japan,
however,

proved that lachrymatory-factor synthase, (a previously undiscovered
enzyme) is the culprit (Imani et al, 2002). Lachrymatory-factor synthase is released into the air when we
cut an onion. The synthase enzyme converts the amino acids sulfoxides of
the onion into sulfenic acid.


The unstable sulfenic acid rearranges itself into syn-ropanethial-S-oxide. Syn-propanethial-S-oxide gets into the air and comes in contact
with our eyes. The lachrymal glands become irritated and produces
the tears! For
more print resources. onion,
lachrymal gland and crying or tears
in the. Unless you ve avoided cooking, you ve probably cut up an onion and experienced the burning and tearing you get from the vapors it produces. When you cut an onion, you break cells, releasing their contents.


A chemical process results, eventually releasing a compound that causes you to tear up when you re slicing and dicing. Amino acid sulfoxides form sulfenic acids after you slice into an onion. Enzymes that were kept separate are now free to mix with the sulfenic acids to produce Бpropanethiol S-oxide, a volatile sulfur compound that wafts upward toward your eyes. This gas reacts with the water in your tears to form. The sulfuric acid burns, stimulating your eyes to release more tears to wash the irritant away. There are a few ways to stop the chemical process that causes you to cry when you cut an onion, including: Cook the onion.


This process inactivates the enzyme, so while the smell of cooked onions may be strong, it doesn t burn your eyes. goggles or run a fan. This actually prevents the vapors from the compoundб entering yourб eyesБor at least blows the compound s vapors safely away. Refrigerate your onion before cutting it. Doing so slows reactions and changes the chemistry inside the onion. You can accomplish the same thing by cutting the onion under water. Use stainless steel. The sulfur-containing compounds also leave a characteristic odor on your fingers.


You may be able to remove or reduce some of the smellБand tearsБby wiping your fingers on a. There are a few other ways to cut into or prepare an onion while avoiding the waterworks. These involveб cooking prep methods, such as locating the root, removing the bulb and even slicing lengthwiseБat least before you dice the vegetable. So, take heart. With a little preparation, forethought, and understanding of basic chemistry, you can slice, dice and cook an onion and never shed a tear.

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