早餐3桌:怎样知道一只蛋的新鲜程度?|How to tell how fresh an egg is?

早餐1

怎样知道一只鸡蛋的新鲜程度?
How to tell how fresh an egg is?

鸡蛋是早餐桌上一个重要食材!炒蛋,煎蛋,水煮蛋,水波蛋等等都需要用到新鲜的鸡蛋,甚至,需要用到新鲜程度不同的鸡蛋。

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.

那么,问题来了!

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?

答案是:一杯清水就可以了!

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.

1long
1周内的蛋:放进水后,蛋的大头端会向上稍稍翘起,尖头端仍贴着杯底;打破蛋壳后,可见蛋黄会稍扁一些,浓蛋白和稀蛋白依然界线清晰。

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.

2long

2周或以上的蛋:放进水后,蛋的大头端明显向上翘得,甚至会垂直于杯底;打破蛋壳后,蛋黄扁平且明显缺乏弹性,浓蛋白明显减少甚至消失,蛋周围液体增多,浓蛋白和稀蛋白界线模糊甚至消失。

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.

3long

变质的蛋:蛋大头端垂直于杯底,整只蛋浮出水面。打破蛋壳后,蛋黄变色,稍稍摇动就会散开,蛋白全是液体,此时鸡蛋甚至会发臭。

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.4

 

充满好奇心且求知欲强的厨友此时会问:

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?

这要先来了解鸡蛋的结构。

We need to start from the construction of an egg.

鸡蛋的结构|The construction of an egg

Schematic of a chicken egg. Illustration showing the bird egg anatomy.

Schematic of a chicken egg. Illustration showing the bird egg anatomy.

刚生下鸡蛋,蛋内空气含量非常少。随着放置的时间增加,空气以及一些微生物会通过具有透气性的蛋壳进入到蛋内。与此同时,蛋内水份会随之蒸发,微生物会与蛋内物质发生化学反应。

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.

刚生下的蛋,蛋内空气及微生物很少,所以蛋在水中几乎没有任何浮力。打破蛋壳后可以看到饱满有弹性的蛋黄浓蛋白较多且与浓蛋白与稀蛋白的界线清晰可见。随着存放时间的增加,蛋内的多层结构会发生改变。存放时间较长的鸡蛋,蛋黄会变得扁平且弹性下降,稍微震动则会破裂而出现散黄蛋,而浓蛋白的面积会转化为液体,所以浓蛋白的面积会变小甚至消失,稀蛋白会增多。

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.

现在,你们大概已经明白浮力测试的原理所在了。

Now, you guys might already get the theory in the experiment.

对烹饪鸡蛋追求极致的厨友会再问:

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?

鸡蛋放置时间的长短会直接影响蛋内物质的结构和状态。如果你是个讲究的厨娘/厨子,你一定想知道究竟用怎样的蛋才能做出完美成品。下面是两个对鸡蛋的新鲜程度有要求且要求不同的例子:

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

煎蛋(特别是希望蛋黄保持完整)和做水波蛋(特别是希望蛋白层尽量厚)时,选一只尽量新鲜的鸡蛋是关键中的关键。原因是新鲜的鸡蛋蛋黄有弹性,和周边蛋白紧黏在一起,浓蛋白层粘稠且面积大,这样煎蛋时不仅蛋黄不容易散(即使翻转时也不易散开),煎出来的蛋白层面积也足够大。而用尽量新鲜的蛋做水波蛋就更关键了!!新鲜的蛋放进水中后,蛋白会紧紧裹在蛋黄周围,不易散开。同样地,成品的蛋白层也会更厚。

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

可以用刚生下的鸡蛋来做水煮蛋吗?当然可以!只是,剥蛋壳时会非常困难!刚生下的鸡蛋蛋壳膜会紧紧粘在蛋壳和蛋白上,所以剥壳时很容易连蛋白一起剥出,影响蛋表面的光滑。所以做水煮蛋时,我们一般选择一周左右的蛋。这样的蛋不但依然新鲜,而且因为放置了数天,空气进入蛋内使得蛋壳膜稍松弛。用这样的蛋做水煮蛋就能轻松剥壳了啦。

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.

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