Why are some hard-cooked eggs easier to peel than others?
Ironically, the hard-cooked eggs that are most difficult to peel are usually fresh eggs. As mentioned above, properly handled eggs that are a few days old contain more CO2 than old eggs, so their albumen has a lower (less basic) pH value. The difficulty you may encounter in removing the shell of a fresh hard-cooked egg has been associated with the low pH of the albumen. As stored eggs lose CO2 , the albumen pH rises; when these eggs are hard-cooked, they are easier to peel. Thus, eggs that have been stored in the refrigerator for about a week are usually easier to peel when hard-cooked. If you are unsure about the age of a carton of eggs, you can check the sell-by date on the carton. Regulations require that the sell-by date be no more than 30 days from the packing date. If more than 23 days remain before the sell-by date, the eggs may not peel well. Why do boiled eggs have grayish-green yolks? When eggs are boiled for a long period of time and cooled too slowly, iron and sulfur (two o
