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!


The delicious science of the Maillard Reaction

Roast turkey on Thanksgiving! Who doesn’t love it? In fact, the best part of the bird, really, is that luscious brown, crispy turkey skin. So much flavour! And so pretty!

But what makes that delicious crust? If you said, “caramelization,” you’re close. The process by which sugar is turned to carmel happens in a lot of the same ways. But the real hero of this story is a complex and barely-understood process called the Maillard Reaction.

In short, the Maillard Reaction is the process by which amino acids, sugars and heat form to create hundreds of different chemicals, many of which create the many subtle flavors that make roasted or seared meats so delicious and some of which are brown, therefore adding to the color.

The Maillard Reaction is common to a variety of forms of cooking and lots of different types of foods. Roasting, searing, frying and grilling meats, breads and vegetables of all kinds benefit from this mystery reaction.

So, if you want to make your food taste even better this holiday season, remember the Maillard Reaction and plan for it:

  • High heat is key to this reaction. If you are cooking something big – like a turkey – best to cook at a low temp until nearly cooked, then crank the heat for the last bit to get that Maillard deliciousness working. This is especially good because..
  • Water evaporates at 200 degrees or so, but the Maillard Reaction happens around 300 degrees. Why does this matter? Because excess water on what you’re cooking will rob the food of the energy necessary to make the Maillard Reaction happen. It either won’t happen or will happen after the food has dried out!
  • The higher the water content in the food, the less likely to get that lovely brown color. Also, pan-frying things will increase the likelihood of that nice browning because its so close to the fire.