5 FALSE MYTHS ABOUT EGGS
For World Egg Day and in conjunction with Tecnozoo Egg Week, we have decided to debunk 5 false myths about eggs.
THE SHELL COLOR DEPENDS ON THE DIET: FALSE
There are various shell colors for eggs, although most consumers are familiar with the typical brownish-pink or white eggs commonly found in supermarkets.
Some breeds of hens lay eggs with colors ranging from blue to brown. The dominant pigment in brown eggs is protoporphyrin IX, with traces of other porphyrins: biliverdin, coproporphyrin, and uroporphyrin, while blue eggs are colored by biliverdin.
The expression of these pigments, and thus the shell color, is genetically determined. However, the intensity of color, uniformity of color, and other factors can depend on the age of the hen, health conditions, environment, and diet. Since diet does not affect shell color, the nutritional properties of the egg are not related to this, and it is not true that a brown egg is more nutritious than a white egg.
A MORE COLORED YOLK INDICATES A MORE NUTRITIOUS EGG: FALSE
The color of the yolk is an important organoleptic aspect for consumers and is often associated with egg quality.
The color of the egg yolk is determined by the type and profile of carotenoids present in the feed, their concentration, and their intestinal absorption. The yolk color does not affect the lipid or protein profile of the egg, and therefore its nutritional characteristics.
It is also true that physiological changes in the animal, such as aging, stress, or health conditions affecting pigment absorption, can influence yolk color intensity. However, these variations mostly affect the uniformity of color from egg to egg within the same group.
The main carotenoids used in poultry nutrition to modulate yolk color are xanthophylls that give a yellow color, such as zeaxanthin and lutein, or those that give a red color, such as canthaxanthin. The pigments used are mainly synthetic, but they can also be found in various food sources: corn is rich in zeaxanthin, while alfalfa is rich in lutein. Spices also represent a great source of natural carotenoids.
A ROOSTER IN THE HENHOUSE INCREASES EGG PRODUCTION: FALSE
Roosters are not necessary for egg laying. There is no scientific evidence of a correlation between the presence of a rooster and egg production.
Egg production is regulated by light hours. The hypothalamus is responsible for the hormonal mechanism that leads to egg production, and light stimulation regulates its activity. 14-16 hours of light are sufficient to stimulate full hypothalamic activity, which is why, in non-intensive farming contexts (no light programs and environmental management), a decreasing photoperiod (shorter days) often corresponds to a reduction in egg production.
Therefore, the rooster is not necessary for egg laying. In fact, fertilized eggs are not commercially available for food use, and the shelf life of the product (the time between production and consumption without health risks) is reduced.
EGG CHOLESTEROL INCREASES THE RISK OF CARDIOVASCULAR DISEASE: FALSE
For many years, the high cholesterol content in eggs was directly correlated with increased blood cholesterol levels and thus a higher predisposition to cardiovascular diseases.
More recent studies have disproved the direct correlation between cholesterol intake and blood cholesterol levels and have shown that the mechanisms regulating cholesterol levels are much more complex and multifactorial. Likewise, the onset of cardiovascular diseases related to high cholesterol is complex and multifactorial.
Studies agree that consuming up to two eggs a day does not lead to significant changes in cholesterol levels in people without particular metabolic issues.
THE WHITISH FILAMENTS NEAR THE YOLK INDICATE FERTILIZATION: FALSE
The filaments found near the yolk, in close contact with the vitelline membrane, are called chalazae and are the result of the egg’s rotation in the oviduct. They are protein structures that anchor to the egg’s poles and suspend the yolk in the center of the egg.
These structures are entirely normal and have nothing to do with fertilization.
Furthermore, commercial eggs are not fertilized.
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BIBLIOGRAPHY “5 FALSE MYTHS ABOUT EGGS”
- Arch.Geflügelk – “Variation of eggshell colour in different egg-type chickens”
- Dr. Ekaitz Maguregui – “The egg yolk color and pigments”
- Samiullah Khan, J R Roberts, Kapil K Chousalkar – “Eggshell color in brown-egg laying hens — a review”
- P J H Jones – “Dietary cholesterol and the risk of cardiovascular disease in patients: a review of the Harvard Egg Study and other data”
- Silvia Cerolini, Margherita Marzoni Fecia di Cossato, Isabella Romboli – “Avicoltura e coniglicoltura”
