Double-yolked eggs are the result of a hen releasing two yolks in quick succession. The two yolks travel down the hen’s oviduct together and are encased in a single shell.
I’ve never gone out of my way to purchase double-yolked eggs, but I recently learned that many people do. Tempted by a chance of finding a double yolk, Redditors exchange tips on finding the rare eggs. Certain companies, such as Sauder’s Eggs, promise a dozen double-yolked eggs in cartons called Double Yolkers, a feat made possible by shining a bright light on each egg before packaging.
But what creates a double-yolked egg in the first place? I decided to find out.
How Are Double Yolks Produced?
Double yolks are a byproduct of ovulation, and their production is almost identical to that of a single yolk egg. In a typical egg-producing cycle, a hen releases a yolk from its follicle in one of its ovaries 30 minutes after laying an egg. The yolk travels down the oviduct (the fallopian tube, aka the egg’s assembly line), which produces albumen (egg whites) and shell materials along the way. Eventually, at the end of the oviduct, the egg is encased in a shell. (Each yolk contains a germinal disc, which, if fertilized, develops into a baby chick. In fertilized eggs, the yolk is the primary source of nutrition for the embryo, but in store-bought eggs, the yolk remains dormant and becomes part of the edible egg.)
The same logic applies to double-yolked eggs. Sometimes a hen will release two yolks in quick succession, and the two yolks will travel together down the oviduct before they are encased in a single shell. Young and old hens are particularly prone to releasing double yolks, since both experience irregular production cycles as they ramp up or wind down egg reproduction.
Some eggs can even contain more than two yolks. According to the Guinness World Records, Diane Hainsworth of Hainsworth Poultry Farms in New York reported finding an egg with nine yolks in 1971, the most ever reported. On the flipside, eggs known as dwarf or fairy eggs contain no yolks whatsoever; young hens typically lay these as they start their reproductive cycle for the first time.
What to Do If You Find a Double Yolk
These eggs are completely safe to eat, and for dishes like scrambled eggs and omelettes, you can cook them like any other egg. They look particularly striking when hard-boiled, and the extra yolk gives omelettes and scrambles a bright golden hue.
If you’re baking, however, note that one double-yolked egg is not equivalent to two whole eggs. A standard large egg contains about one tablespoon of yolk and two tablespoons of egg whites. Since a double-yolked egg typically contains more yolks than whites, it can throw off the fat-to-sugar ratios in desserts, such as lemon curd and chocolate pot de crèmes, resulting in an undesirable texture. It’s not usually a big deal, unless you accidentally crack a double yolk into your batter. To avoid that, always crack eggs into a small bowl first. If you find a double yolk, you can weigh the yolk and white separately and adjust by adding more egg white as needed.
Beyond cartons of Double Yolkers, double-yolked eggs exist in the wild, too. According to Pete & Gerry’s, their largest eggs—jumbo or super jumbo—are most likely to contain double-yolked eggs laid by mature hens. Eggs from small-scale producers at farmers markets may also carry double yolks, as their eggs are less likely to undergo egg candling, a scanning process used in the commercial egg industry to identify and remove double-yolked eggs in the name of quality control. If you find a double-yolked egg in your carton, you may find another one, as egg producers often group eggs by age of the flock.
I may not actively scavenge for double-yolked eggs, but I’m always delighted when I find one. I think of them as a brilliant surprise from nature, and a sure path to an extra-delicious scramble.
