Harold McGee had good advice. Apparently super fresh eggs are difficult to peel because the pH of the white is more acidic which causes it to adhere to the shell membrane more tightly. Two solutions here – use older eggs or add a little bicarb soda to the cooking water to increase the pH.
Why do my boiled eggs not peel properly?
The albumen (white) of a just-laid egg contains a store of dissolved carbon dioxide, a weak acid. … At the lower pH of a fresh egg, the proteins in the egg white bind tightly to the keratin in the membrane during the cooking process, which makes it nearly impossible to remove the shell without chunks of white attached.
How long do you boil an egg for hard?
How long to hard boil eggs?
- 7 minutes for a medium egg.
- 8 minutes for a large egg.
- 9 minutes for an extra-large egg.