Why We Do It and How to Stop It
I just read an article in which the author waxed rhapsodic over the virtues of onion goggles. In case you're not up to speed with the concept, these are actual goggles designed to fit tightly over your eyes when you chop an onion, the purpose being to keep you from tearing up. Apparently, they're all the rage and even come in cool designer colors.
My first reaction was, “Yikes! What a wimp!” Then I realized I was being unfair; just because I don't cry over chopped onions doesn't mean that it's not a problem for some people. I'm not sure it's such a problem that I'd shell out twenty bucks for funky looking eyewear, but, again, that's just me. So, why do some people get all weepy when chopping onions while some people don't? And what can those who do do about it, short of popping for a set of dedicated – and silly-looking – goggles?
Okay, we've all seen the cartoon chefs crying rivers of tears as they cut up onions, but does that actually happen in real life or is it just a corny comedic device? The answer is, it depends on your sensitivity to the chemical elements involved. Onions contain a complex combination of acids and enzymes within their cell structure. When you cut into an onion, you open up those cells and all hell breaks loose. Amino acid sulfoxides reform into sulfenic acids that combine with an enzyme called allinase to produce a volatile sulfur compound called Propanethiol S-oxide. The more you cut, the more cells you rupture and the more sulfur compound you release into the air. The gaseous compounds in the air interact with the moisture in your eyes to form a mild sulfuric acid that irritates your eyes and stimulates tear production to wash it away. Once the onions are cooked, the enzymes are deactivated, so no more tears. But in the meantime.....
On the good news front, Vidalia and other sweet varieties of onion have higher concentrations of sugar and water that serve to dilute the offending enzymes. Scientists have even developed a “no-tears” onion that is grown in low-sulfur soil. But if you're using plain old yellow onions and their sharp, tangy cousins, you're in for a crying jag if your eyes are particularly sensitive to the sulfuric gas. Mine aren't, but my wife's are, so guess who gets to chop onions in my kitchen?
You may ask, “Why are your eyes less sensitive than hers?” And I'll tell you: contact lenses. Contacts sit on the front surfaces of your eyes, in front of the cornea where most of the affected nerves are located. So in the first place, they form a sort of protective barrier. Also, because people who wear contacts are accustomed to having “foreign bodies” in their eyes, they naturally produce more tears to keep flushing away the stuff that builds up on the contacts. That's why lens wearers tend to blink more often. And that's why the mild sulfuric compound doesn't affect them as much; between the barrier effect and the tear production, the irritating gas never gets to the surface of the eye.
So, other than getting your contact-wearing spouse or friend to cut up your onions, what do you do? The very first defense against onion-induced tears is a very sharp knife. Slicing cleanly through the onion cells will produce fewer irritants than crushing them. I was helping a friend prepare a casserole the other day and the alleged knife she handed me to cut onions with mashed them more than it cut it them. I could tell by the smell that anybody else would have been standing in a puddle of tears. I don't carry my Victorinox chef's knife with me everywhere. Maybe I should.
Another slick cutting trick involves minimizing your exposure to the freshly-cut cells. When you make that first cut, turn the two halves of the onion cut side down against the board. And try to do that with subsequent cuts, too. It'll really help. So will removing the chopped onions from the vicinity. Don't try to cut them all into a heaping, reeking pile right under your eyes and nose. As you work, scrape the chopped pieces into a bowl and move it off to the side. You may not look as much like Julia Child, but you'll look a lot less like those cartoon chefs.
A simple trick if you want to keep your eyes dry is to start with chilled onions. Cold inhibits the evaporation rate of the irritating gas. Don't keep your onions in the refrigerator or you'll be very disappointed with the results. But it's okay to stick the ones you're preparing to cut in there for 15 or 20 minutes.
If you've got a vent hood over your stove, turn it on “high” and cut your onions near it. The vapors will get sucked up before they get to you. Even working under a ceiling fan will help.
Now, there are some tips and tricks circulating out there that make me go “hmmmmm.” I've never tried any of them, but I'll repeat them here for the sake of keeping good urban legends going. Feel free to give any or all of them a shot.
The most common advice of this type is to cut your onion under or near running water. I can see why “under” would work, but I'm not so sure about “near.” I'm also not sure I want to dilute the onion flavor by holding it under running water. And I'm definitely not sure about trying to control the cut pieces as they scatter through the standing water or get blasted by the running stream. Another watery tip says to have a kettle or pot of boiling water near your cutting area. The steam supposedly helps dissipate the vapors.
Some people swear by breathing through the mouth while cutting onions. Theoretically, the gas sticks to your wet tongue and bypasses your olfactory nerves. I think this theory is all wet because it's the nerves in your eyes that get irritated, not the ones in your nose. Admittedly, the two are somewhat interconnected and sucking up onion fumes through your nose is not especially pleasant, but that's not where the tears come from. However, if you want to be a mouth-breather, you have my blessing.
You might also like the tip that involves lighting a candle near where you're cutting the onion. The theory is that the flame will burn off the fumes before they get to you. I don't buy it, but if you pick a nice scented candle, at least your kitchen won't smell like onions. And if you're Catholic, lighting a candle never hurts, anyway.
Another weird wives tale says to leave the root intact because the root is where all the bad stuff is. Wrong. The entire onion is made up of “bad stuff.” Yeah, there might be more of a concentration of it near the root, but it's still in other parts of the onion, too. There is a legitimate point to leaving the root intact: it makes the onion easier to cut and chop.
Chewing gum or sticking a piece of bread in your mouth while chopping away are a couple of methods I've seen recommended but for the life of me, can't figure out why.
Finally, there's those goofy goggles. Yes, they really work. No, I'm not going to pay twenty bucks for them. I don't care about the designer colors. A cheap pair of swimming or safety goggles will work just as well. But remember to take them off before you leave the kitchen. Otherwise, you'll amuse the adults and frighten the children and small animals.
Of course, if you really want to be on the safe side, you could cut up cold onions under running water with a fan going and a candle burning next to a steaming teakettle while wearing goggles and breathing through your open mouth into which you have inserted a piece of bread. Oh, and did I mention whistling? Some people say whistling helps. And you might do it while standing on one foot. That has nothing to do with onions, but it would increase ticket sales.
Now that's entertainment!