Question: Is it necessary to use vinegar when poaching an egg?
By: Camille Willemain
Published: January 11, 2011

I've seen recipes and instructional videos for poaching an egg and some require adding vinegar to the poaching liquid while others don't. How does adding vinegar affect the poaching process?

Answers:
Dr. Mitchell R....

Camille,
While it's not strictly a requirement to use vinegar to poach an egg, it does cause a more rapid setting and cooking of the egg white.  This can lead to a more compact poached egg, with fewer egg white "streamers."
When using vinegar in the poaching water, never use more than 1 tablespoon  (half an ounce) per pint of water.  I use a bit less.
The chemistry is an important consideration.  Vinegar, an edible acid, helps to "denature" the albumin proteins in the egg white (which is about 10% proteins and 90% water in a fresh egg).  In layman's terms, this means the individual proteins unfold and begin to interact more strongly with their neighbors, making a strong network of protein-protein bonds.  (Think of one piece of string, as compared to fishnet; or a ball of twine after a kitten has played with it.)  This network causes the white to "set," and the egg becomes solid.  With vinegar, this happens  more quickly than with heat alone.
Chris Paulk

It's not necessary but, vinegar is added to water to assist in the coagulation of the albumin. It holds the egg together. You can poach an egg in water, or whatever liquid you like, with or without vinegar.
Barnaby Dorfman

We've found that salt in the water also helps with the setting and flavoring.
Carla Saunders

I'm afraid I don't like the hint of vinegar taste so I cheat a little. i soft boil an egg then peel it under the cold water tap. I pop it on buttered toast and voila, I have my poached egg on toast!