What are the chemical reasons vinegar helps with poaching eggs?
Cooking an egg involves denaturing its proteins with heat. Acid can also denature proteins and cook the egg. When you first add a raw egg to the simmering water, it takes time for the proteins to absorb heat and denature. During this time, the egg can deform into threads of congealed protein, and look… not nice. The acid in the vinegar helps to denature the protein more quickly, thus maintaining a better appearance. Swirling the water to form a vortex (pocket for the egg) can help accomplish the same end. See Related Links.
