Egg whites are key players in many recipes and often are the reason for recipe failures. Egg whites should whip up high in volume yet be stable, moist and soft enough (even with stiff peaks) to fold easily into batter or spread for meringues. These tips will help make sure your whipping efforts succeed.
Temperature
To ensure the greatest yield when whipped, whites should be at room temperature. Because warm eggs are harder to separate, however, separate them while they are still cold. Then bring the egg whites to room temperature by placing them in a bowl that is then set in another bowl of warm water.
Hand Separation
The best way to separate eggs is with your hands. This is because you are less likely to break the yolk. Place two bowls on the counter. Crack the egg, and dump the yolk and egg white into one hand, over one of the bowls. Spread apart your fingers slightly to let the white fall through, into the bowl. Place the yolk into the other bowl. Make sure you thoroughly wash your hands before and after separating eggs.
Shell Rescue
If you contaminate the whites with a small amount of yolk, use the shell to scoop out the yolk.
Clean Equipment
Make sure the bowl and beaters are clean and free of fat. Even a small amount of fat, such as egg yolk or oil, can contaminate the whites and prevent them from whipping properly. As a precaution, lightly wipe the clean mixing bowl and beaters with vinegar or lemon juice.
Best Bowl
A copper bowl is ideal to use for mixing whites. There is a chemical reaction between the copper and the whites, resulting in more stable whites. If you do not have copper, use a stainless steel bowl.
Slow Start
Begin beating whites at medium-low to low speed until they are frothy. Then increase the speed to medium-high or high and beat continuously until they reach the desired stage.
Whisk by Hand
If you consistently have problems with over-beating whites, try whipping them by hand using a copper bowl and a large balloon whisk with lots of fine tines. Doing so produces more stable whites and it is nearly impossible to over-beat them.
Perfectly Whipped
Whites are perfectly whipped when they remain stable, even if you tip the bowl upside down.
Folding Egg Whites
Sponge-style cakes are light and airy in texture. The cakes owe their texture to beaten egg whites and sugar that are folded with egg yolks and flour. The cakes' leavening, or rising power, comes entirely from the egg whites, so the step of folding the egg whites is critical. If you mix the batter too much when folding, the eggs will deflate and you will have a flat cake.
After the egg whites and sugar have been beaten to stiff but not dry peaks, add the egg yolk mixture and half of the flour. To keep the mixture light and airy, add the flour using a sieve of sifter.
To fold the mixture together, bring a rubber spatula straight down into the mixture and slide it across the bottom of the bowl, bringing it up the side and turning over the mixture. Move the bowl one-quarter turn and repeat the process until most of the flour has been incorporated. Not all of the flour will be completely mixed in - this is okay.
Sift the remaining flour over the mixture, and repeat the folding process. This is a gentle process in which you are trying to keep as much air in the egg mixture as possible, so you want to be careful not to over mix. When you are finished, the batter should be light and airy; there may even be a few traces of flour or egg white that are not mixed in. If you over mix the batter, your cake may stay flat and not rise.