Generally speaking, the fresher an egg is, the harder it is to peel it. Eggs that have been laid for a few days are easy to peel. That's because fresh eggs have enough water. At the moment when the egg is cooked and fished out, the water in the egg white will evaporate with the pores on the eggshell, so it will stick to the eggshell, while the egg left for a long time will not evaporate so much, so this will happen.

The fresher an egg is, the harder it is to peel it. Foreign food magazines have suggested that it is perfect to boil eggs in the refrigerator for 7 to 10 days. With the passage of time, many characteristics of fresh eggs have gradually changed.

Among them, there are two factors that have the greatest influence on egg peeling-the first is the acidity and alkalinity of egg white, and the second is the content volume of egg. The egg white of fresh eggs just laid contains carbon dioxide produced by previous metabolism, so the egg white is slightly turbid, and the pH value is about 7.6 to 7.9, which is a relatively acidic condition.

After coming into the world, eggs can exchange air with the outside world through porous eggshells-inhaling oxygen and releasing carbon dioxide-in fact, eggs are breathing.

The loss of carbon dioxide increases the alkalinity of egg white and raises the pH value. Generally, after three days, the pH value of egg white rises to about 9.2. 2 1 day, rising to 9.4. The maximum is 9.7.

In addition, eggs will gradually lose some water through porous eggshells during storage. So fresh eggs of the same size are always heavier. When placed in water, the freshest eggs will sink, while old eggs will sometimes float.

The loss of water directly leads to the reduction of the contents of eggs, which provides an expanding space for the air chamber between eggs and eggshells, and forms a tiny gap between the inner and outer membranes, which naturally helps us peel eggs.