It is almost common knowledge that eggs are nutritious, earning them grand titles such as "the world's most nutritious breakfast," "an ideal nutrient reservoir," and "the highest quality protein." But did you know that different cooking methods, such as boiled, steamed, poached, or scrambled eggs, have a significant impact on their nutritional absorption? Below, authoritative nutrition experts provide a detailed analysis of egg nutrition and list a "ranking of egg cooking methods" to tell you which cooking method is best for absorbing the most protein, benefiting your heart, and supplementing vitamins.
Protein is all in the egg white
When eating eggs, you're essentially consuming two parts: the egg white and the yolk. Some believe the yolk is nutritious and discard the white, eating only the yolk. Others, fearing weight gain, eat only the white and throw away the yolk. So, which is more nutritious, the yolk or the white?
Actually, the egg white and yolk each have their own advantages, but their nutritional components are very different. Besides 90% water, the remaining 10% of the egg white is mainly protein. Don't underestimate this 10% protein, as it contains most of the protein in an egg. Professor Lin Xinying from the Institute of Nutrition and Food Hygiene at Shandong University also pointed out that egg protein is second only to breast milk in terms of utilization by the human body. It is one of the highest-quality proteins in food. It is recommended that people with low immunity, especially those who have just had surgery, eat more egg whites to supplement protein.
Compared to the egg white, the nutritional components of the yolk are much more complex. All the fat in an egg is concentrated in the yolk, but most of it is fatty acids beneficial to the human body. It also contains oleic acid, the main component of olive oil, which is beneficial for preventing heart disease. In addition, vitamins A, D, E, K, and minerals such as phosphorus and iron are mostly found in the yolk. Although the absorption rate of iron is relatively low, it is crucial for infants who cannot eat meat. At the same time, the yolk also contains a very important substance—lecithin, which is particularly important for brain development and also has the effect of lowering cholesterol. The color of the yolk also hides a rich nutritional code: it contains riboflavin to prevent cracked corners of the mouth, as well as lutein and zeaxanthin that protect the eyes. Often, the darker the yolk, the higher the content of these vitamins.
Some people fear the cholesterol in egg yolks, but this is a very mistaken idea. If the serum cholesterol in the human body is too low, it can lead to low immunity and affect the strength of blood vessels, which is also not good for cardiovascular health. Therefore, for healthy people, eating one or two egg yolks a day is very healthy; for people who already have high blood lipids, eating half a yolk a day is more appropriate.
Among all foods, the ways to cook eggs are almost the most diverse. Fan Zhihong, an associate professor at the College of Food Science at China Agricultural University, who is dedicated to culinary and nutrition research, has listed three rankings of egg cooking methods for us based on various research and experimental data. In the end, it was found that on every list, "boiled egg in its shell" ranks first.
"Heart-Healthy Ranking":
First place: Boiled egg in its shell. Without a drop of oil, a low cooking temperature, and the cholesterol in the yolk not being exposed to oxygen (once oxidized, cholesterol becomes one of the most serious threats to cardiovascular health), it is the most heart-healthy way to eat eggs.
Second place: Poached egg.
Third place: Egg drop soup and steamed egg.
Fourth place: Fried egg.
Fifth place: Scrambled egg (thin omelet). This refers to an egg pancake made with a small amount of oil over low heat, so the cholesterol in the yolk is not oxidized much.
Sixth place: Scrambled eggs. After the eggs are beaten and scrambled, the cholesterol in the yolk is in full contact with the air, resulting in more oxidation. Eggs absorb oil easily, so the amount of oil used is also large.
"Best Protein Digestibility Ranking":
First place: Boiled egg in its shell. Research shows that the protein digestibility of a boiled egg is as high as 99.7%, almost completely absorbed and utilized by the body.
Second place: Fried egg and scrambled egg (thin omelet). The protein digestibility of these two methods is 98%.
Third place: Scrambled eggs. Protein digestibility is 97%.
Fourth place: Steamed egg. Protein digestibility is 92.5%.
Fifth place: Raw egg. Protein digestibility is only 30%-50%.
"Vitamin Retention Ranking":
First place: Boiled egg in its shell. Low heating temperature retains nutrients comprehensively.
Second place: Steamed egg. Low heating temperature results in less loss of water-soluble vitamins such as riboflavin and lutein.
Third place: Poached egg. Low heating temperature results in a slight loss of water-soluble vitamins.
Fourth place: Fried egg. High heating temperature leads to the loss of both fat-soluble vitamins (A, D, E, K) and water-soluble vitamins.
Fifth place: Scrambled egg (thin omelet). High heating temperature leads to the loss of all vitamins.
Sixth place: Scrambled eggs. High heating temperature results in significant vitamin loss.
Soak the boiled egg for 5 minutes
Just knowing which egg cooking method is best is not enough. If the operation is incorrect, it not only affects the texture but also impacts nutrition and can even produce harmful substances.
Boiling eggs: Eggs should be placed in cold water, heated slowly, and simmered over low heat for 3 minutes after boiling, then soaked for another 5 minutes after turning off the heat. This method results in tender egg whites, a firm but not overcooked yolk, optimal protein denaturation, and is easiest to digest. Eggs boiled for more than 10 minutes not only become tough in texture and lose a lot of vitamins, but the protein also becomes difficult to digest.
Poaching eggs: Crack the egg into boiling water, then turn to low heat to cook through. For savory poached eggs, you can add tomatoes, greens, etc. For sweet ones, you can add fermented glutinous rice, red dates, goji berries, and other ingredients.
Steamed egg custard: Do not add oil or salt when beating the eggs, as this can easily damage the egg colloid, making the custard coarse and hard. Do not stir vigorously; just stir a few times to ensure it's even before steaming. Also, adding a little milk when steaming the custard can make its texture smoother and increase its nutritional value.
Fried egg: It is best to use low heat and a small amount of oil. Some people like to fry the egg white until it's crispy, which not only loses nutrients but may also produce carcinogens. It is best to fry only one side until the egg white is set.
Scrambled egg (thin omelet): Use a small amount of oil and medium heat is best. If the omelet is a bit thicker, it is more conducive to retaining nutrients.
Scrambled eggs: Medium heat is best; avoid high heat, as it will cause significant nutrient loss and make the eggs hard. But the heat shouldn't be too low either, because over time, too much moisture is lost, the eggs become dry, and the texture is affected.