How to tell how fresh an egg is?
Egg is an essential ingredient for making breakfast! Scrambled eggs, fried eggs, hard boiled eggs, poached eggs, etc., all require fresh eggs, even different level of freshness.
So, here comes a question!
怎样知道一只蛋是否新鲜，有多新鲜？| How to know if an egg is fresh or not and how to tell how fresh it is?
The answer is: all you need is a glass of water.
浮水测试法｜ Floating test?
以上小实验中我们可以看到｜The above shows ：
非常新鲜的蛋：放进水后，蛋会直沉杯底并水平躺着；打破蛋壳后，蛋黄饱满有弹性; 浓蛋白黏稠,面积大且紧紧裹着蛋黄; 稀蛋白面积小；浓蛋白与稀蛋白界线清晰。
If an egg is very fresh: the egg will sink to the bottom of the glass and sit horizontally when placed in a glass of water; if you crack it, you will see a rounded,plump yolk that sits up proudly. The white has a thicker,gelatinous layer that clings all around the yolk. The outer layer is thin. The line between the thick layer and the thin layer is obvious.
If an egg is a week old egg: it will lie semi-horizontally and tilt up slightly on the round size; if you crack it, the egg yolk is flatter but the two separate textures of whites are still visible.
If an egg is 2 or more weeks old: it will tilt up significantly or?even to a vertical position, but the other side will still be touching?the bottom. If you crack it, the egg yolk is very flat and no?flexibility; The thick layer of white reduced or even disappeared and?more liquid in the outer layer; The line of thick white layer and thin?white layer is not visible or even disappeared.
If the egg is stale: It will float in a vertical position. If you?crack it, the colour of the yolk gets darker and the yolk will disperse;?The egg white becomes all liquid; The egg will even sting if you smell it.
Those Chooers that are full of curiosity will keep asking:
为什么新鲜程度不同的蛋在水中以及打破蛋壳后的状态会不同？| Why there are such difference?
We need to start from the construction of an egg.
鸡蛋的结构｜The construction of an egg
In a newly laid egg, there is hardly any air inside the egg. With?time passing, air and some micro-organism will get into the egg through?the breathable egg shell. At the same time, the moisture content of the?egg begins to evaporate and the micro-organism will have a chemical?reaction with the egg.
In a newly laid egg, there is little air and micro-organisms, so?there is no floating power when placed in the water. Also, when you?crack a newly laid egg, you can see a plump and flexible yolk, a big?thick white layer and two clear rings in the egg whites. When the egg is?older, the structure of the egg inside will change. The egg yolk will?get flatter and the flexibility will decrease, the thick white layer?will turn to liquid.
Now, you guys might already get the theory in the experiment.
Those who pursue excellence in cooking will keep asking:
烹饪鸡蛋时为什么不是越新鲜的鸡蛋越好？| Why a very fresh egg isn’t always the best?
The age of the egg will directly affect the structure and status of the?materiel inside. If you are very conscious of your cooking, you must?want to know the tricks of producing a perfect egg dish. The following?are two different examples to show you how the freshness of an egg will?affect the final dish:
煎蛋（荷包蛋／太阳蛋）和水波蛋：鸡蛋越新鲜越好｜Fried egg ( Over-easy/Sunny side up)& Poached egg: The freshest egg
When you pan fry an egg (especially if you want to keep the egg yolk?complete) or poach an egg (especially if you want the egg white to?thickly wrap the yolk), it is vitally important to choose a very fresh?egg. The reason is the freshest egg’s egg yolk is flexible and the egg?white tightly clings to the yolk. In this case, it is not easy to?destroy the yolk when you flip over the egg. Also, the fried egg will?have a bigger egg white. Using the freshest egg to make a poached egg is?more key. The freshest egg ensures the egg white won’t disperse in the?water when you poach it and the final dish will have a thick egg white.
水煮蛋｜Hard boiled egg
So, is there any problem to use the freshest egg to make a hard boiled?egg ? Of course you can but the only problem is it will be very?difficult when you peel off the shell! The new laid egg’s cuticula is?taut and stick to the egg shell and egg white. This explains why, if you?hard-boil a really fresh egg, peeling off both the shell and skin is?torture and easily affects the egg white. Therefore, we usually use the?egg that is a few days or even a week old .In this case, the skin will?become looser and the egg will peel like a dream.