Eggs are a common ingredient in the list of baby food supplements, and every time I go to the market and supermarket, I observe that many elderly people like to pick rough eggshells, and it is better to bring a little, thinking that such eggs are fresher and fresher just taken out of the chicken nest.
Is this selection really reliable?
What kind of egg can be considered a "good egg"?
Are different colors of eggs the same nutritional value?
1. How to choose a fresh egg?
Look at the appearance
As mentioned above, in fact, my mother also thought that "eggs with a slightly dirty egg shell are fresh eggs", which is not a minority of people.
In fact, dirty eggs do not mean that eggs are fresh, and dirty eggs are eaten raw without sterilization, which is at risk of infection with bacteria.
The right way to pick:
We can pick up the egg and shake it slightly, and the more pronounced the sound we hear, the less fresh it may be.
(Probably because the egg's air chamber becomes larger and the yolk becomes thinner because it has been stored for too long.) ）
However, most eggs now have a production date, so you can tell from the packaging whether they are fresh or not.
Look inside
The inside of the egg is mainly composed of two parts: egg white and egg yolk.
Eggs of similar size, opened and poured on a plate, the yolk and egg white can maintain the height and freshness is proportional to the freshness, the fresher the egg shape, the more "firm and full".
(This is because the total number of molecules in the yolk is more than the egg white, and the difference in osmotic pressure caused by the difference in concentration creates an irreversible trend: the water in the egg white will always transfer to the yolk.) ）
What is a "loose yolk egg"?
Eggs from the moment it is laid, it opens the countdown to freshness, every day there will be a small amount of water from the egg white to the yolk transfer, which makes the yolk continue to expand, while the yolk also because of the "dilution" becomes soft, the appearance becomes more flat, and finally the yolk membrane wrapped in the yolk will be broken, the yolk overflows, it becomes what we often call "loose yolk egg", and the egg at this stage is already very unfree.
The egg whites of fresh eggs are thick and hazy, while the egg whites that have been left for a long time become loose and easy to flow, and look clearer and more transparent.
(This is because in the process of egg "aging", the alkalinity of the yolk and egg white will gradually increase, the pH directly affects the polymerization state of the protein, the higher the alkalinity, the less conducive to protein aggregation, and the degree of agglomeration will affect the deflection of incoming light.) ）
In addition, the length of time the egg is stored directly affects the taste of the egg, and freshness is the king who determines whether an egg is delicious or not.
The longer the egg is stored, the worse the taste, and after a certain amount of time, the egg white will even emit a faint sulfur smell, and the yolk will also emit an uncomfortable fishy smell.
2. Is the egg color linked to the nutritional value?
You will find that there are many kinds of eggs on the market, including brown, yellow, light yellow, white and so on. What's the difference? Who has higher nutritional value?
In fact, the color of the eggshell has little to do with the nutrition of the egg.
Bin Jie provides you with an egg nutrient composition analysis table, it is easy to see that their nutrient differences are not large.
So why can we see so many different colored eggshells?
Bin sister here to give you a popular science, eggshell is mainly composed of calcium carbonate, calcium phosphate and a small amount of protein, if there is no pigment involvement, eggshell should be white. There are three main types of pigments in the eggshell: protoporphyrin, biliquillin and the metal chelate of biliquillin, under the action of this "three primary colors", we can see eggs in white, red, brown and other colors.
Depending on the breed of chicken, the color of the eggs produced will be different.
In addition, there is some relationship between the color of the eggshell and the thickness of the eggshell. The darker the color, the thicker the eggshell. This kind of egg is less easy to break when slightly bumped, and it is relatively resistant to storage.
About author:Wang Bin, child nutritionist, China registered dietitian, national second-level public nutritionist, national senior nutrition lecturer. Good at combining medicine with modern nutrition knowledge, focusing on the field of maternal and infant nutrition and health, teaching you to feed your children scientifically.