Wow, In doing research for Ask-A-Chef generally I will need to dive deep. How deep you may ask? Reading 3-5 dry scientific journals that have as many numbers as they do words, deep. But thankful sous vide eggs are not the most difficult one to find information on. It’s a bit cliche to sit here and promote how incredible and edible eggs are but it really is true. They’re self contained protein packed packages that makes so many foods possible. We will never know who the first person to use an egg for cooking was but they were the first great innovator in food history. They and the person who decided to use fire should be on the cooking Mount Rushmore along with Careme, Escoffier, and Adria. We are often asked about egg replacement in all types of food, this article may help explain why there is no single perfect egg replacement out there as well since egg gelling is so unique in how it works. What makes eggs so special and how can sous vide help you perfect the perfect ingredient.
“How can you perfect the perfect egg?”
Eggs are made up of many different proteins, only a couple of these proteins react during the heating process. As the egg is heated the different proteins will coagulate and gel at different temperatures. This is very surprising to people as they cook their first eggs sous vide. Cooking an egg to 147-155°F will yield a solid fudgey yolk and a semi soft egg white that almost falls off the yolk. For me the yolk at this temperature is perfect but the white leaves much to be desired. Across the grades of eggs, the yolks are pretty consistent for sous vide within a few degrees. But what is the perfect temperature for an egg white. Traditionally we are used to the yolk being the last thing to cook in an egg. Think of an over easy, poached, or soft boiled egg. They all have a perfectly set white and a runny yolk. This is because of how the heat is transferred to the egg. Cooking an egg in either in a pot of boiling water or a frying pan bombards the outside of the egg with high temperatures and cook the whites first. The gentle heat of cooking sous vide only allows you to heat to specific temperatures and not one degree higher. The egg white will not cook first. So what is the perfect temp for cooking an egg white? First we need to look at all the proteins found in egg white, here is a list :
Ovoglobulin G2: 4%
Ovoglobulin G3: 4%
While all these proteins make up the egg white, two of them will unravel and cause the gelling. The first one that gels is the Ovotransferrin, this is the egg protein that causes the semi firm egg whites. This protein begins gelling at 140°F and will continue to around 183°F. At 180°F Ovalbumin also known as albumin gels. This is the distinct firm gelled egg white that you can best associate with a hard boiled egg. A soft egg can be sous vide at 150°F for an hour and then cracked into a pot of 180°F water to make a perfect poached egg. An egg can be cooked to a perfect 6 minute soft boiled egg and then shocked in an ice bath before cooking sous vide at 150°F to create the perfect hard boiled egg that is not chalky or crumbly. While eggs are the perfect ingredient creating the perfect egg all boils down to finding that exact recipe that can be replicated every single time and thankfully sous vide helps us achieve that.
Quick tip: Always use grade AA for egg cookery and custards. Other grades (A or B) of eggs can be used for baking without affecting the quality. The quality of eggs do play a part as the higher the grade, the egg whites will be more firm. The lower quality eggs will have egg whites that do not set at the same temperatures. This also goes for custards where both egg yolks and egg whites are being used. In custards like flan where you use whole eggs they will need to be of a high grade to achieve the most consistent results.
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