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Science

Onions are so good for you, they’ll make you cry

Sometimes, there’s nothing better than a good cry. This is especially true when chopping onions, although not for the emotional release. The component in that pungent misty stuff in onions that irritates the heck out of our eyes is scientifically known as lachrymatory factor, appropriately derived from the Latin word lacrima, which means “tear”. Interestingly enough, lachrymatory factor is actually doing us a a few excellent health favors, possibly even protecting us against cancer. Doesn’t seem like such a terrible chore now, does it?

Onions are naturally rich in two health-benefiting compounds: flavonoids and sulfur-containing compounds. Flavonoids are typically found at high concentrations in the skin and outer layers of onions with yellow, brown, red, or purple coloring. These compounds are also potential antioxidants that could protect us against heart disease, cancer, and aging. The sulfur-containing compounds are where onions give us their taste, odor, and – you guessed it – misty tear gas. So what does this mean?

When an onion is cut, sulfur compounds are released into the air. These compounds are broken down into an unstable intermediate and can then either turn into lachrymatory factor or spontaneously turn into thiosulfinate. This thiosulfinate is not only responsible for the onion’s distinct odor and flavor, but also converts into other sulfur-containing compounds with potential health benefits including anti-inflammation, anti-blood clotting, anti-cancer, anti-asthma, and lowering cholesterol levels. Sounds great to me, and I don’t even like onions!

Maybe you do enjoy onions in your favorite Thanksgiving recipes but you don’t particularly enjoy crying – who could blame you? Never fear; scientists have been working on bringing tear-free onions to the general market since 2008. Tear-free onions were originally developed by Crop & Food Research of New Zealand and House Foods Corporation of Japan. These onions look and taste like regular onions but have lowered activity of lachrymatory-factor synthase through genetic modification and thus do not make your eyes water upon chopping or crushing, but still increase the production of beneficial thiosulfinate – which means none of the tears with all of the health benefits!

Unfortunately, commercializing genetically modified foods is no simple task, so it will probably be a few more years before we find tear-free onions in the Wegman’s produce section. However, the largest share of the liquids and therefore, of the phosphates that make us cry are found in the tips of the bulb – the northern and southern hemispheres, you might say. To avoid getting too much juice out into the air and minimize the crying, try not to cut into the poles too much. This is why classical French technique only has you cut into the poles once, as demonstrated here for a tear-free Thanksgiving feast preparation:

[youtube]http://www.youtube.com/watch?v=fff1xobJ4BQ[/youtube]

In the meantime, keep chopping your onions with the knowledge that through your tears come wonderful health benefits! And hey, while you’re at it, check out our Turkey Day Turkeys playlist and tell us which “turkeys” you think we should add!

Categories
Science

Tasty T-Day Science: why does vinegar keep poached eggs together?

Yum. Poached eggs. The stuff of foodie dreams, with the runny yolk that makes a sauce for whatever lies beneath it. And for those of you who get your Thanksgiving on early in the day (and there are lots of you, don’t lie), your day of thanks may very well begin with one of these delicacies on toast. Or a Toad in the Hole, for you Brits.

If you’ve noticed, most people who make poached eggs with some regularly tend to use a few drops of vinegar in the water. Why is this? The answer has nothing whatsoever to do with flavour. It has to do with physics and specifically, with a concept known as molecular polarity.

But let’s back up a step. Poaching is about cooking food in hot water. Boiling, essentially. The thing with an egg is: you face the obvious problem of trying to poach something which is itself liquid. Dropping the egg into a pot of boiling water should, we would expect, cause the egg to spread out evenly in the pot. But that is not what we want when we poach an egg. We want a nice, fluffy cloud of egg that can be taken out whole and dropped onto whatever foods we wish to bathe in unctuous goodness. This requires that the white or albumen of the egg poach quickly and more or less in one place.

Water’s molecular structure. Note the polarity of the two elements. Photo:

The trick, though, is that water has a chemical structure that is built to be magnetic. With its negatively-charged oxygen ion on one side and its positively-charged hydrogen ion on the other, water forms a natural magnet. That magnetism is called molecular polarity, and allows it to do two things: create a meniscus at the top of a column of water and more importantly for our discussion, naturally adhere to other surfaces.

An example of water’s molecular polarity in action. Note the beads of water formed by surface tension.
Notice. Them.
Photo: Blue Waikiki

That ability to adhere to other surfaces is the problem, because it’s what draws the egg out of its nice shape and into nastiness. But vinegar, while it still has some molecular polarity, is nowhere near as magnetic. By introducing a few drops of vinegar into the water, you can change the overall ability of the cooking liquid to leech albumen out of shape.

So, yet another reason that vinegar is a must-have for any kitchen, even if you don’t particularly like the taste. What else is vinegar good for? Well, it is a natural counterbalance to heat. If you’ve made that chili a wee bit too hot for the little ‘uns, add a couple of dashes of vinegar to the pot. You’ll never taste the acid of the vinegar, but the heat will be magically cut. Hmm… Maybe I just came up with another Tasty T-Day Science article…

And Spotify users, don’t forget to check out Jillian and I on Spotify, where we’ve created a Turkey Day set list of truly awful “turkeys.” Great, cheesy fun!