Why do we add vinegar when we are poaching an egg? | Te Wāhanga Pūtaiao / Faculty of Science | Te Herenga Waka—Victoria University of Wellington (2024)

FAQs

What is the primary reason for adding vinegar and salt to the water while poaching an egg? ›

Using vinegar in the poaching water can help the egg whites coagulate faster and reduce feathering, however, it is not a necessary ingredient. Some prefer to poach their eggs without vinegar for a more delicate flavour.

It's completely optional and not even necessary, but if you do want to try it, stir one tablespoon of distilled white vinegar into the boiling water before you add the eggs. Can you poach more than one egg at a time? If you're hosting a brunch party, you may want to poach more than one egg at time—and you can!

When vinegar is added to eggs, its acetic acid combines with the calcium carbonate in the eggshell to produce carbon dioxide gas and calcium acetate. This reaction creates an acidic environment in the container, which can cause the egg whites to denature and become opaque and rubbery.

Vinegar (acid) breaks apart the solid calcium carbonate crystals (base) in the eggshell into their calcium and carbonate parts. The calcium ions stay dissolved in the vinegar (calcium ions are atoms that are missing electrons), while the carbonate goes on to make carbon dioxide — the bubbles that you see.

The vinegar contains ethanoic acid (also known as acetic acid), which reacts with calcium carbonate in the eggshell. One product of the reaction is carbon dioxide gas, which appears as little bubbles forming on the eggshell. Over time, this chemical reaction dissolves away the hard eggshell.

Most food dyes are acid dyes, so called because they only work in acidic conditions. The vinegar---a solution of 5 percent acetic acid in water---is there to bring the pH low enough that the dye will actually bind.

The vinegar in the water makes the eggs easier to peel. Here's why: The vinegar's acid not only dissolves some of the calcium carbonate in the shell, it also helps the whites set faster. Running the hard-boiled eggs under cold running water as you're peeling, meanwhile, helps the shell separate from the membrane.

The shell of an egg (typically a chicken egg) is made up of primarily calcium carbonate. If you soak this egg shell in vinegar (which is about 4% acetic acid), you start a chemical reaction that dissolves the calcium carbonate shell.

Perfectly poached eggs are truly a treat at breakfast or brunch. Whether they're spilling their soft golden yolks onto Canadian bacon and rich hollandaise in eggs Benedict, or served atop avocado toast, the runny, creamy yolks and firm yet delicate whites make these eggs a delicious addition to any dish.

The acidity or sourness of vinegar brightens the flavor of food and adds balance to a rich dish. It is found in popular kitchen staples like salad dressings, marinades, sauces, mayonnaise, and ketchup. Vinegar can change the texture of foods.

What happens if you poach an egg without vinegar? ›

Do you need to add vinegar to poach eggs? Adding a splash of vinegar to the water sets the whites faster, so you have fewer wispy bits. However, if you follow the other tips this extra step usually isn't necessary.

Adding a capful of vinegar to the pot ups the overall acidity, increasing the rate at which ovalbumin (the predominant protein in albumen, aka “the egg white”) denatures, in turn, solidifying the shape of a poached egg much faster.

This is because the water in the vinegar can enter the egg through the membrane, moving from the higher water concentration in vinegar to the lower concentration in the egg. If you now put the egg in water, it will grow in size a lot more due to the much larger water concentration gradient across the membrane.

Here's how to do it right:

Fill a tall pot with water, salt it well, and add 3 tablespoons of vinegar per 1 gallon of water. (The vinegar helps to coagulate the egg.) I prefer a deep pot because I love how the egg develops a teardrop shape as its plunges into water and sinks to the bottom.

If the water is hot enough (near boiling), salt increases the density of the cooking liquid just enough to make the egg bob to the surface when it's about perfectly done. While you can certainly poach eggs without the salt and vinegar, they'll want to sit on the bottom of the pan and thus cook unevenly.