Today’s lesson is about eggs and their role in baking. In pastries, eggs act as a glue that helps bind things together. They add proteins, moisture, and fat to baked goods, and give structure and texture to a dish. Egg whites act as a leavening agent, and when heated, stirred, or whipped, the proteins in egg whites uncoil and then recombine. This process creates a network of proteins that traps air or liquid, which can result in a range of textures, depending on the other ingredients. These proteins force out moisture when they are heated, which results in puffy, but dry pastries (think meringue cookies!). Egg yolks, on the other hand, give moisture and richness to baked goods that you cannot get from egg whites alone. When eggs are whisked, they can trap enough air to to make a foam, which gives a light airiness to recipes like souffles and mousses. In batters and doughs, the water in eggs expands when you bake them, helping them to rise.
When eggs are stirred over heat (such as in custard), the protein coils remain short due to being agitated. This prevents a solid network of long protein strands from forming, resulting in a smooth, spoonable consistency. Then, when in the oven, since you are no longer stirring the mixture, longer strands of protein form and allow a firm structure to form for your final product.
Tip: Brushing the top of breads and pastries with an egg wash (mixture of water or milk and egg) before baking makes the resulting pastry glossy.
Eggs at Room Temperature
Most recipes call for you to use room temperature eggs. I’m sure – like I have – many amateur bakers often brush this step aside as unnecessary and an inconvenience. I am here to report this is not true! At room temperature, eggs, butter, and milk bond and form an emulsion that traps air. The resulting batters are smooth and evenly dispersed. Better egg dispersion results in more even baking and a lighter texture because, in the oven, the air expands, producing light, airy, evenly baked goods. Cold eggs, on the other hand, don’t incorporate with fats like butter and shortening well. They don’t mix as nicely with other ingredients to bond, resulting in not as delicious treats, such as denser cookies and cakes, and harder breads.
…If these sciencey reasons don’t convince you, it is simply easier to blend room temperature eggs into a recipe. At room temperature, egg whites are more “relaxed”, combining with yolks and breaking up in batter more easily. They also get more volume when beaten. In addition, cold eggs can actually firm up butter that you so nicely softened for easy mixing, giving your batter a slightly curdled look (it is usually fine to continue on if this happens, though).
Bringing eggs to room temperature
You can take eggs out of the refrigerator 30 minutes to a few hours before using them. If you are about to start baking and realized you didn’t take your eggs out, here is a quick-cheat method that works quite well: Put the eggs in a warm water bath for about 5-10 minutes. You want to ensure the water isn’t too hot – we don’t want to cook our eggs!
Now, your egg temperature generally won’t have a big impact on your basic cake recipe. If you are making a cake that requires many eggs, or a more delicate cake (such as angel food, pound, or chiffon cake), you should definitely use room temperature eggs. These more demanding cakes rely on air incorporated during beating the eggs for their main source of leavening. When made with cold eggs, these light cakes do not rise properly because cold eggs don’t whip as well as room temperature eggs. The resulting cakes will be too dense.
As a general rule, use room temperature eggs and your cakes will be lighter and fluffier.
Another thing to note is that eggs are easier to separate when they are cold. Unfortunately, most recipes calling for just egg whites want them at room temperature too, and, like we said earlier, this gives them more volume after processing, so we want to listen! Now, you can still separate eggs at room temperature, or alternatively, you can put the cold, separated egg whites or yolks in a small bowl and place this bowl in a slightly larger bowl of warm water for 5-10 minutes, to bring them to room temperature.
Storing egg whites and egg yolks
When I have a recipe calling for just egg whites or egg yolks, it pains me to throw the other parts of the egg down the drain. Luckily, I recently learned that you can actually save them for later use! Egg whites can be stored covered in the fridge for a few days. If you want to save them for longer, you can freeze them! Wow! Who knew?!?! (Not me!) A convenient method is to pour each egg white into one cube of an ice tray and freeze them. Once frozen, just put the cubes in a bag and take them out whenever you need them. Egg yolks are slightly trickier, and don’t save quite as long, since freezing them is not really a good option (though I did read that you can freeze them if you mix them with a little salt or sugar first. They also will dry out in the fridge after just a day. The best way to store them is to keep the yolks whole and add a little water to the container they are in. They can be kept for 2-3 days in a covered contained this way. Still, if you bake a lot, this may be enough time for you to waste not an egg yolk!
…That’s all I have for you on eggs. I hope you learned a much as I did! See you next time!
Put you new knowledge to use with these recipes!