This week's Ask a Baker question is one I was CLUELESS about prior to working in the kitchen at Muddy's Bake Shop:
"A lot of recipes call for room temperature eggs. Why? Just how important is it to bring your eggs to room temperature?"
Such a great question! I have to say, being a baker in a large-scale homestyle kitchen--where we crack literally hundreds of eggs a day--gives me a unique perspective on this one.
The short answer to this question, gleaned from year of experience baking with both cold and room temperature eggs: Room temperature eggs do not make that big of a difference when baking with recipes calling for both the yolk and white, provided they are added to the butter/sugar mixture slowly (and with some recipes, this step is not even necessary). HOWEVER, if your recipe calls for egg whites only, room temperature eggs are the bomb! You want to use room temperature egg whites for recipes requiring them, but I recommend only bringing them to temperature after separating them. Cold eggs separate best!
So why are room temperature eggs recommended? Let's talk about the egg protein albumin for the third blogpost in a row! (Apparently albumin is some important stuff in the baking world.) Egg whites are composed of 90 percent water and 10 percent protein, mostly the protein albumin. When eggs are cold, the albumin is more tightly wound and less inclined to unwind and join its peers than when the egg is room temperature. This is why when you are making something which relies on egg white fluff for its volume--like angel food cake or meringue--you want to use warmer egg whites rather than whites straight out of the refrigerator.
If you are baking cookies or a cake beginning with creamed butter and sugar, you have another reason why room temperature eggs might be recommended. When cold eggs hit butter, the butter chills and becomes solid once again. If your batter has a lumpy, curdled look to it in spite of the softened butter you used, it is likely because you added too cold eggs too quickly. Adding eggs one at a time (or slowly, in the case of a cake batter requiring 24 or more eggs, like we often encounter in the Muddy's kitchen!) allows the temperature of your egg-butter-sugar mixture to remain in a safe range.
As for the benefits of added volume and lighter texture attributed by many to room temperature eggs, we have yet to see much of a difference between cold and room temperature eggs in our Muddy's cupcakes and cakes. They say that in the olden days--that is, prior to today's ultra-powerful hand mixers and stand mixers--when you beat eggs into any type of batter, they would hold more air more quickly if they were room temperature. And that is likely true. However, we must remember that our mechanical mixers today are super-powerful and can create those bubbles whether the eggs are cold or not!
While egg temperature makes but a negligible difference in Muddy's cake batter, cookies are another story altogether.
We don't necessarily always use room temperature eggs for cookies, but we do have a major egg policy involving our cookie dough. Muddy's bakers must add eggs one at a time to any batch of cookie dough, no matter what. If a baker does not follow this direction, it is immediately obvious in the baked cookie.
Cookies made with all of the eggs dumped in at once will cause the butter to freeze up--sometimes just microscopically--but for some reason the reaction causes a very ugly cookie. We call them "lizard skins," and no, I am not going to mess up a batch of cookies just to take a picture to show you what this looks like. Just imagine lizard skin, a crackly, scaly-looking mess. Blech.
So how do you bring an egg to temperature, especially if you don't have the 30 minutes (or more) to leave it out on the counter? It's simple: just place the egg in a bowl of lukewarm water, and the egg will come to temperature in no time! And remember, all the proteins are looser in your egg when it is warm, so you will want to separate your eggs--if your required by your recipe--while they are still cold to keep your yolks from breaking. Just place your bowl of egg whites into a container of lukewarm water, and voila! Room temperature egg whites!