What kind of eggs are fresh? How to save eggs? Do eggs need to be cleaned? What is the nutritional composition of eggs? Do eating more eggs cause cholesterol and arteriosclerosis?
These questions, I believe that many people who have the power to master the kitchen can answer one or two or three points. However, if you can guarantee the accuracy, you need to discuss it.
Professor Tong Qigen from the School of Food Science and Engineering, Beijing Agricultural College answered some questions about eggs.news world ahmed
To distinguish whether the eggs are fresh, just five strokes
First move, see, touch, listen, sniff
Look: Observe the appearance, color, cleanliness, etc. of the egg. Good quality fresh eggshells are clean, delicate, bright color, regular egg shape, no cracks, soft skin, obvious pores, etc.; inferior eggshell color is bright, black or dark black, with oily leaching, there is more More or larger mildew.
Touch: The fresh egg is sinking in the hand, it has a pressing feel, slightly rough; the egg is light in weight and the surface is smooth.news world ahmed
Listen: Gently shake the egg at the ear, if the egg has a sound or the material in the egg has a large vibration, it is a poor quality egg; put a few eggs in the hands and touch each other, if the sound is really good If the sound is like knocking the sound of the tile, it is a sticky egg and a stinky egg. If it is a "beep" sound, the egg must have cracks.news world ahmed
Sniffing: Use your mouth to gently sip a hot breath on the eggshell, then sniff the smell with your nose. The good quality egg has a slight lime smell, and if it is a poor quality egg, it has an odor.
The second trick, the more thick protein, the fresher the egg
The protein is also called egg white. The protein is layered and is divided into four layers from the outside to the inside in the whole egg. The first layer is a thin protein, the second layer is a thick protein, the third layer is a thin protein, and the fourth layer is a ligated layer of concentrated protein.
During the storage of the egg, the proportion of concentrated protein in the newly produced egg is about 60%, but as time goes on, the thick protein is converted into a thin protein. Therefore, the amount of thick protein can represent the freshness of the egg.news world ahmed
The third trick is to buy eggs in summer, more than 25 days of production date is not recommended to buy news world ahmed
Usually, the eggs in the farmer's market are the freshest, but nowadays people rarely have time and energy to go to the farmer's market to buy eggs. More often, they go to the supermarket to buy packaged eggs. Boxed eggs do not mean that the eggs are not fresh, but the circulation time is longer.
Buy the boxed eggs in the supermarket must carefully check the production date. If it is hot summer, and the egg output has been more than 25 days, do not buy it. It is recommended to buy eggs under 15 days. If the weather is cold and the eggs are always stored in the refrigerator, then the eggs will not be edible for more than 35 days. Of course, it is not recommended to buy eggs that are longer than the date of manufacture.news world ahmed
Also pay attention to check the shelf life of the boxed eggs. Different manufacturers' eggs have different shelf life. This can only be used as a reference. The eggs that are about to expire will be bought less or not bought. Brand and price are also important reference bases, and the quality of large brands of eggs is guaranteed.news world ahmed
The fourth stroke The longer the storage time, the larger the gas chamber, the less fresh the egg
At the blunt end of the egg (large head), the balloon formed by the separation of the protein membrane and the eggshell membrane is called a gas chamber. The air chamber of the egg is formed only at the blunt end, mainly because the blunt end is larger and larger than the vent of the tip eggshell. During the storage of the egg, the moisture in the egg is lost from the pores of the egg to the air, making the chamber larger, and the longer the egg is stored, the larger the chamber will be, so the size of the chamber and the freshness of the egg It is also one of the main indicators for evaluating the freshness of eggs.news world ahmed
The fifth trick Eggs with blood stains, feces and various stains on the surface of the eggshell, it is best not to buy
If there are too many blood stains or feces on the surface of the egg shell, it means that the egg is heavily polluted. The bacteria may penetrate into the inside of the egg through the pores on the surface of the egg. It is best not to buy such an egg.
"It is not advisable to eat protein without egg yolk"
It is very popular in the market to "eat only protein and not eat egg yolk", but I don't know how to lose most of the nutrients in the egg.news world ahmed
87% of the protein is water, while the egg yolk has a water content of only 50% and a protein content of 15%, far exceeding the protein. In addition, vitamins and minerals such as calcium and phosphorus are also basically in the egg yolk.
Many people worry about the fat and cholesterol in the egg yolk. In fact, the egg yolk contains lipids, not exactly the fat in the usual sense, because it includes not only cholesterol but also lecithin. Lecithin in egg yolk is four times that of cholesterol, and lecithin is a beneficial ingredient for cardiovascular health. Studies have also shown that choline in lecithin can prevent Alzheimer's disease.
So far, there is no direct evidence that eating eggs must lead to an increase in the probability of arteriosclerosis. Therefore, it is not advisable to blindly abandon the egg yolk.
N ways to safely store eggs
Although every family has a refrigerator, how to use the refrigerator to store eggs safely has a doorway.
It is not recommended to store the eggs in a closed container: because the eggs are living organisms, they should also breathe and discharge the waste. If sealed, the flavor of the eggs will deteriorate.
Use a few to take a few to avoid "secondary pollution": When using eggs, do not take the container for storing eggs out of the refrigerator, but how much to use directly from the refrigerator, avoid taking it out of the refrigerator and put it back, This will make egg storage difficult. Because the eggs will be condensed out of the surface after the eggs are taken out of the refrigerator, the bacteria and microorganisms in these beads will enter the egg and shorten the egg's shelf life.
Eggs should be placed with their heads upright: When storing, it is best to erect the eggs in the egg box board and pay attention to the big heads. The top of the big head is the air chamber. As the storage time increases, the thick protein gradually decreases, and the egg yolk will go up. If the small head is facing up and there is no obstruction of the air chamber, the egg yolk is easy to stick directly on the egg skin, resulting in a shell egg.
Scientific egg washing can prevent pollution and extend shelf life
Do you want to buy the eggs you bought? In fact, if the purchased eggs are not dirty, they do not need to be cleaned before storage, because cleaning may shorten the shelf life of the eggs. If you buy more eggs with more stains, be sure to wash them before storing.
If it is cleaned, what is scientific?
First of all, when you wash eggs, you must not soak the eggs directly in the water, otherwise it will easily cause pollution. The correct way is to first wet the surface of the eggshell, then wipe the dirt with a wet wipe, and finally rinse.
Secondly, the water temperature of the egg wash is preferably higher than the egg temperature, that is, water having a temperature between 36 ° C and 38 ° C. This is done in consideration of the fact that the egg has pores, and the water whose temperature is higher than the temperature of the egg does not easily enter the egg through the pore.
Finally, the cleaned egg is preferably boiled in hot water at 90 ° C to 95 ° C for 2 to 3 seconds, then the surface is dried and stored. After this treatment, the egg's shelf life will not decrease, but will increase.
