Jan 21 2010

In Search of The Perfectly Cooked Egg – Sous Vide Style

January 21st, 2010 at 9:27 am (AST) by Jake Richter

As mentioned in my previous postings about sous vide cooking, my own adventures and exploration of sous vide started with the noble egg. Eggs are a wonderful natural food, and for those of you interested in the specifics of an egg’s composition, characteristics, and cooking, I again have to recommend Harold McGee’s “On Food and Cooking, 2nd Edition“, pages 68-117.

I still recall my first encounter with a sous vide cooked egged in a restaurant a couple of years ago, and after trying it I was in gastronomic heaven – the whites were like a soft, delicate custard, while the yolk was thick, rich, and gooey. I could not believe that I had simply settled for chewy, poorly textured, and mediocre eggs all my life. But if you don’t know about alternatives, you never know what you might be missing.

I personally am a huge fan of liquid yolks, and prefer my traditional eggs over easy or poached, and so my first sous vide cooking foray was to make the perfect soft-boiled egg.

McGee explains that egg whites and the yolk are composed of a variety of different proteins, all of which coagulate (solidify) at different temperatures, with the proteins in the egg whites thickening at higher temperatures than the egg yolks. He indicates that egg yolks tend to thicken at around 150°F / 65°C, and the various proteins in egg whites thicken at temperatures ranging from 145°F / 63°C to 180°F / 80°C.

Experiment #1 – Eggs au Naturel @ 64°C – Failed

My first attempt involved just putting the eggs in a water-bath at 64°C to get still runny but nearly solid yolks. Turns out it was a bad idea to put the eggs in the water directly, as they cracked slightly from both the temperature and from bouncing around as a result of the current caused by the immersion circulator, gumming the immersion circulator up with wisps of egg white as a result. I managed to get it clean, but it provided a great first lesson about cooking in a water bath – make sure that your ingredients are sealed away from the water to ensure the water remains clean and pure.

Experiment #2 – Eggs Sous Vide @ 64°C – Better

For the next experiment in cooking eggs sous vide, I actually used sous vide – I vacuum sealed the eggs to prevent them from cracking into the water bath and gumming up the works.

A Multivac vacuum sealer with a pouch with two raw chicken eggs

A Multivac vacuum sealer with a pouch with two raw chicken eggs

Here too I learned something. Normal sized eggs are less likely to crack when you vacuum seal them into a bag than bigger eggs. I assume that’s because big eggs are likelier to have thinner shells. I learned my lesson quickly, and only cracked one egg out of the dozen or so I used during my experiments.

Two vacuum sealed raw eggs in a Multivac vacuum sealer

Two vacuum sealed raw eggs in a Multivac vacuum sealer

One of the interesting things about cooking in a low-temperature water bath is that for most things, as long as your temperature is within a proper range for the thing you’re cooking and you have reached the point where the food has reached the target temperature throughout, you can cook the item for a wide range of time and still achieve the same result. Thus, the result of cooking an egg at 64°C for an hour is not hugely different from cooking it for three hours or five hours. The same applies to many meats in my experience.

Putting the vacuum sealed eggs in the water bath

Putting the vacuum sealed eggs in the water bath

With that in mind, I cooked my sous vide eggs at 64°C for around two hours. When I took them out of the bath and cracked them open, I found the yolks were unfortunately a bit more solid than I would like, but the whites had that wonderful light custard texture. The rest of the family agreed the yolk was too firm, and found the whites a bit runny.

A Sous Vide cooked egg at 64°C with a barely solid yolk and creamy whites

A Sous Vide cooked egg at 64°C with a barely solid yolk and creamy whites

Experiment #3 – Eggs Sous Vide @ 63°C – Perfect Yolks

Undeterred, I sealed up some more eggs and cooked them for a couple of hours at a slightly lower temperature – 63°C. The result was the whites were a wee bit runnier, but still like a delicate custard, and the egg yolks were perfectly cooked – gooey and rich but fully cooked. However, the rest of the family was still not wild about the consistency of the egg whites.

A Sous Vide cooked egg with a thick and gooey yolk and creamy whites - cooked at 63 degrees Celsius

A Sous Vide cooked egg with a thick and gooey yolk and creamy whites - cooked at 63 degrees Celsius

The yolk of the 63 degree Sous Vide cooked egg - rich and thick

The yolk of the 63 degree Sous Vide cooked egg - rich and thick

Experiment #4 – Long-cooked Eggs @ 70°C

As I was curious about the effect of long cooking of eggs to see whether time really doesn’t make a difference, I also cooked some eggs at 70°C for about 10 hours while I was experimenting with cooking pork ribs in the water bath at the same time.

The yolk was firm, but creamy, and the whites less runny but still delicate. This inspired the next and final (for now) experiment.

Experiment #5 – Separately cooking the whites and yolks

For the final egg sous vide experiment, I took eight eggs and separated the whites and yolks into two cooking-safe bowls. While I am certainly capable of separating whites and yolks using just the egg shell itself, I find I am more productive with a dedicated separating device as pictured below. Plus, it’s cute. Trick to using it properly is to slide the egg innards into the device instead of dropping the egg insides onto the device, as the drop creates enough force that the egg yolk membrane might burst.

Jake's way to separate egg yolks and whites

Jake's way to separate egg yolks and whites

Eight eggs - separated into whites and yolks

Eight eggs - separated into whites and yolks

Once I was done with separating the eggs, I vacuum sealed each bowl. Another two lessons learned here: First, use bowls or jars that leave about one-third of the top empty – do not fill them to the rim; and second, don’t seal to maximum vacuum – 85-90% vacuum (or 150-100 millibar or so) should be sufficient. Not having known these things, I found my whites and yolks sucked a bit out of the containers during the vacuum sealing process, which in turn burst a couple of the yolks. Fortunately burst yolks still taste good.

The whites and yolks after being vacuum sealed - note that a couple of yolks burst

The whites and yolks after being vacuum sealed - note that a couple of yolks burst

Both were cooked for about an hour at 63°C (to cook the yolks just right). The yolks were then removed along with enough water to keep them warm while the whites got cooked for another hour at 70°C.

Starting the eggs in a water bath - both at 63C, and then the whites for a while longer at 70C

Starting the eggs in a water bath - both at 63C, and then the whites for a while longer at 70C

Result? The yolks were great, of course, and the whites far less runny – just like when I long-cooked the whole eggs, but still custard-like, and most importantly, more to my family’s liking.

Meanwhile, the eggs have been unbagged - creamy rich yolks, and custardy whites

Meanwhile, the eggs have been unbagged - creamy rich yolks, and custardy whites

However, when we are next up for another egg sous vide experiment, we may try the whites at somewhat higher temperatures to see if that makes a difference, since coagulation of some of the egg white proteins is not complete until around 80°C.


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