The question of whether commercial supermarket eggs can hatch is common, often fueled by curiosity about the origins of our food. Generally, eggs purchased from a supermarket will not hatch, primarily because they are unfertilized and undergo rigorous processing.
The Commercial Egg Production Process
Commercial egg production facilities are designed to produce unfertilized eggs. Laying hens are typically kept without roosters, so their eggs lack the male genetic contribution necessary for embryonic development. Hens lay eggs regardless of a rooster’s presence, meaning most store-bought eggs cannot develop into a chick.
After being laid, eggs are collected rapidly to ensure cleanliness and freshness. They then undergo washing with warm water and mild detergent, which removes contaminants and the egg’s natural protective layer (the bloom). This removal makes refrigeration essential to prevent bacterial entry. Eggs are then candled over a light source to detect defects, sorted by size and quality, and packaged. Finally, they are transported and stored at cool temperatures (typically 45°F/7°C or lower), which inhibits any potential cellular development.
What Makes an Egg Hatch
For an egg to hatch, two primary conditions must be met: fertilization and proper incubation. Fertilization requires a rooster to mate with the hen, allowing sperm to unite with the ovum. A developing embryo within a fertilized egg begins cell division even before the egg is laid.
Once fertilized, eggs require consistent and precise incubation. Chicken eggs need 21 days at a steady temperature around 99.5°F (37.5°C) in a forced-air incubator or 102°F (39°C) in a still-air incubator. Humidity is also important, generally 50-55% relative humidity, increasing to 70-85% during the last three days. Eggs must be turned regularly, at least 2-3 times daily for the first 18 days, to prevent the embryo from sticking. Without these specific environmental controls, an embryo cannot fully develop and hatch.
Rare Occurrences and Misconceptions
While most supermarket eggs are unfertilized and processed to prevent development, extremely rare instances of a fertilized egg can occur. This is more likely with eggs from smaller, free-range farms where roosters are present, or with certain poultry species like ducks or quail. Even if fertilized, cold storage conditions typically suppress any embryonic growth.
A common misconception is that blood spots inside an egg indicate fertilization or a developing embryo. These spots are actually caused by the rupture of a tiny blood vessel on the yolk’s surface during the egg’s formation. Blood spots do not signify a developing chick and are safe to consume.