Eggs can be used in many different ways to make meals, cakes, breakfast and sauces. This article concerns only one half of an egg: the white. The white of an egg is the sloppy, transparent part in which the yellow yolk is suspended. When separated from the yolk, egg white behaves very differently and recipes often call for whisked egg whites that are then folded back into mixtures. But of course you have to actually get your white away from the yolk in the first place.
Chefs on television always make cracking and separating eggs look as easy as drinking a cup of tea. They do it with one hand, two at a time, all while talking to the camera. Your average beginner, however, cannot do this; that's perfectly okay.
When separating an egg it is best to choose as fresh an egg as you can get. There is a protective membrane around the yolk; this weakens with age and breaks more easily. This can cause some pretty serious kitchen problems because as soon as any yolk is in the white, it won't really whisk properly. Using fresh eggs reduces this risk considerably. Also leave the egg(s) out for a while before making your food. Cold egg whites make a weaker froth because it is harder to mix the air in.
There are several ways to separate an egg. Some people find one easier than another, so it's really a case of picking the one you feel will work best for you personally. The first, cracking it into a bowl, can be found at Separating An Egg.
Another good way to separate an egg is to crack your egg into a flat-bottomed bowl or lipped saucer, place an egg cup over the yolk and then pour off the egg white into another bowl. Make sure that your egg cup covers the yolk entirely, otherwise you'll break it and the point of separating it will be lost. It is often tempting to just crack the egg and then hold it in your hand, letting the white run off. By all means do this if you like getting egg all over you and will definitely not drop the yolk...and can resist the urge to squeeze it.
Some people have a small gadget called an egg separator. These can take a number of slightly different forms. Upon investigation, however, a cook finds that this is not an exciting new machine that cracks, separates and disposes of the shells. It's a bit like the egg version of a tea strainer and you could just use one of the other, cheaper, methods. Do not bother getting one, it will add clutter to your kitchen.
Storing Egg Whites
Sometimes recipes only call for yolks. A classic example of this is Hollandaise sauce. This can leave an awful lot of leftover egg white. Luckily, egg whites freeze very well, so put leftovers in small containers and pop them in the freezer. Remember to label the container so that you know how much egg there is. Fresh egg whites should not really be kept for longer than a day, and in that time should be stored in the refrigerator.
Whisking Egg Whites
Whisking egg whites is a bit of a skill and needs practice. This is the perfect excuse to make lots and lots of meringues. There is great opportunity for egg white whisking to go wrong, resulting in something that's definitely not what you intended.
What Happens When You Whisk Egg Whites
The entire point behind whisking egg white is to put air into it. As you whisk, the volume of the egg white can actually be increased by about eight times.
As you whisk in the air, bubbles are formed within the egg white. The more you whisk, the smaller these bubbles become and the stiffer the egg white mixture becomes. All the air is introduced in the first thirty seconds of whisking. It is the continued whisking which makes the bubbles smaller. As with a balloon, not enough air in the mixture will cause the egg white to be floppy; too much air and the bubbles burst and collapse. The secret is getting the right balance.
Chefs always say to use a balloon whisk, which to be honest is just a lot of hard work and has the added danger of over-developing the muscles of one arm. An electric hand whisk is the best and easiest thing to use as you can see and feel the whites but you're not having to put in all the power. A food processor can be used, however most people like to be able to see the egg white all the time and some say that a food processor does not expose the white to enough air. It is entirely up to you really... but use an electric hand whisk!
The most obvious thing that can go wrong when whisking egg whites is the introduction of grease. Grease utterly ruins the whisking. In order to avoid this, always make sure there is no yolk in the bowl, then wash the bowl and the whisk in warm soapy water, and then rinse in boiling hot water and dry them with an absolutely clean cloth. This may seem paranoid but finding that you've wasted five eggs can be rather upsetting. For preference use a stainless steel, earthenware or copper bowl. If you must use a plastic bowl, however, rub lemon or vinegar over the bowl. This minimises the level of grease. Of course, some people will now say, 'But I never bother with any of those things! I just make sure I use a clean bowl!' This is of course entirely up to you; neither the author nor the BBC can take responsibility for any grease that may enter your egg white mixture.
How To Whisk
This seems a bit obvious but there are a few important points that will make your whisking experience an easy and joyful experience.
Use a big bowl. This means that as much air as possible is allowed to form bubbles in the egg white.
Start whisking the egg whites at a low speed for about two or three minutes until it all becomes frothy. Then switch to a medium speed for a further minute or so, before roaring forwards to the highest speed setting and whisking until the egg white is done.
When To Stop And What To Do If It Goes Wrong
This is the tricky part. The only thing to do is to keep whisking until you can stick the whisk in the whites, take it out and the whites stand up in pretty well-defined peaks. The top should flop over, but it should have a definite peak-like quality to it.
If you are making a cake, mousse or soufflé then you are going to be folding the egg whites back into the main mixture. You want the egg whites to form soft peaks, which look a bit like melting ice cream. The egg whites will have a glossy, foamy look.
If you're making meringue, however, the egg white needs to make stiff peaks. It will look a bit like slightly sloppy and shiny clotted cream. If you are confident you could turn the bowl upside down; if nothing falls out, then you've whisked sufficiently.
If you accidentally get the whisking wrong and the egg whites are the wrong consistency then it's not the end of the world. The finished product will taste good and unless you were aiming to impress your partner's parents, then it doesn't really matter if it's a bit flat or has exploded slightly. Of course that doesn't mean that you shouldn't care! Cooking is an art, so while the aim is to get it right, things are not always going to be perfect. If you overwhisk your eggs, then there's not much to do except throw it all away and start again. Stiff-peak egg whites aren't going to do the same thing as the called-for soft-peak ones.