All you need to know about – Eggs. As a cook there are a number of ingredients life would be very difficult without and eggs are definitely one of them. Whether it’s in baking, mousses, meringues or just a fried egg butty we use eggs almost every day. Having an understanding of eggs, and how we can use them, opens a wealth of opportunities. It may also shed some light on the how and why of what we do with them, and possibly what went wrong.
Eggs have suffered from a good deal of bad press over the years. Back in 1988 the government put out a warning that vulnerable people should not eat eggs that we not completely cooked through. This was because teats had shown extremely high levels of Salmonella in the egg which if not completely eradicated by cooking would cause food poisoning. I remember some hotels refusing to serve eggs with a runny yolk to protect themselves from possible litigation.
I’m please to say that today that that danger has been averted and the recommendation now states that it is safe to eat UK Lion Stamped Eggs undercooked. If you’re not using stamped eggs, it still a good idea to check if the flock has been inoculated against salmonella.
Always check the use by date on the eggs, this is not only for safety but gives you an idea if the egg is going to be suitable for the use you want to put it to i.e., Poached Eggs take a look at my Poached Egg, Kale and Bacon post for the best method to poach an egg.
What is a fresh egg?
Now let’s have a look at why freshness is important if we want to poach or fry an egg.
look at the image of a fresh egg above, the yolk is sitting central in the white and the white is sitting up proudly supporting the white. Its this robustness of the white that will form the shape of the cooked egg.
Now in the shot above of an old egg, the white is flat, has no strength to it and the yolk is unsupported. try to poach that and you are likely to get a lonely yolk with strands of white string moving around the pan. However the older egg white is more suitable for meringues and could be used for Butter/Sugar Batter cakes. Have a look at the yolk, the deep rich colour may make you believe it’s a better more nutritious egg. it’s could be if its from somebody who has their own birds. Its more likely the colour has been controlled by additives in the chicken feed. This also applies to brown eggs, see below. Where a belief has grown that they will be better. Its of course the classic route to success. Produce what people think or has been led to believe is better.
Eggs are safe to eat after the use by date in fact the F.S.A advice states that “eggs can be eaten after their best before date, as long as they are cooked thoroughly until both yolk and white are solid, or if they are used in dishes where they will be fully cooked, such as a cake”. So if you have some eggs past their best before date, don’t waste them, get your baking hat on!
A very common question at the cook school related to the storage of eggs. Current advice is that you should store them in the fridge at home. But you say, in the supermarket, they are just sitting on the shelf at room temperature? Yes, that’s right, and there is a logic, have a look at the box you bought then in. It’s there to protect them, right? We yes but it also has a second function. Notice that the eggs are stored pointed end down. The blunt end of the egg contains the air sack where bacteria can enter by keeping this at the top, we keep it away from the yolk which will keep the egg fresher longer and protect the vulnerable yolk. Having more of the liquid egg surrounded by the box means the egg will dehydrate less and be less prone to drawing in contamination. This also has the advantage of keeping the yolk in the middle of the egg which looks much better if you are making hard boiled eggs for a salad.
You should also note that the box prevents the shells touching. If the eggs were in contact with each other contamination could spread from egg to egg and spoil the whole batch. So, if you have one of those metal wire chickens sitting proudly on your worktop, send it off to the charity shop and keep your eggs in the fridge in their box. The shell is porous and will ready absorb flavours in the vicinity of the egg. Now this means we need to be careful not to store our eggs close to strong cheese or onions then try and make a sponge with them. Of course, if you have a truffle or two on hand you can place them in a contain with the eggs and infuse the essence of truffle to impress your friends.
Don’t forget though to bring out any eggs you will be using to warm up to room temperature before use.
So, there we have it, now let’s look at an egg itself. There are three main parts. The shell, the white and the yolk. You may have also seen a couple of while strands or blobs when cracking eggs. These are called `chalazae’ think of them as elastic bungees, there function is to support the yolk and keep it central in the egg where it is protected by the white.
Egg whites v Yolks
Yolks.
The yolk contains all the fat of the egg together with the cholesterol. It also has roughly half of the protein in the egg along with most of the vitamins and minerals in the egg. The yolk is a natural binding agent when added to soups, pastry, mousses, mayonnaise, etc. That’s partly due to it lecithin content which is the mystery ingredient when making chefs foams to top off a dish. It’s the binding and thickening ability of the yolk that makes them so valuable in the kitchen. If you have an excess of yolks keep then in the fridge in a small container with a small amount of water covering them to stop a crust forming on top. Check out our Food Files page on Understanding Pastry to see how egg yolks work in pastry.
Whites.
You may argue that compared with the yolk the egg white is uninteresting, not a bit of it. The white is around 90% water with the balance been proteins. The most important of these to us is albumen which is fundamental in allowing the white to hold an important ingredient – Air.
When egg white are beaten the protein begins to unravel known as denaturation. As we continue to beat the eggs these strands of protein begin to hold air. As the air and the water in the white become in contact the protein begins to bond together and hold a foam. This foam become a vehicle for us to introduce air into a mixture like a mousse or a souffle. A very small amount of acid (lemon juice) added to the white after denaturation assists the binding and make for a more elastic foam. If the beating is overdone and the binding is over stretched the foam will begin to collapse and fall in on itself. Adding sugar to the whites once a good foam is created stiffens up the whites and gives stability (meringue). You can still overdo it though and of course you may not want sugar in the dish you are creating. Any fat present in the whites or on the tools we are using will prevent the proteins from binding and its impossible to create a foam. If you have leftover egg whites keep them in the freezer. Not only is this a really handy standby the process of freezing and defrosting breaks down the protein and helps them wisk up to a foam easier than fresh ones.
Personally, I always prefer to whisk whites by hand as I can control the whisking and judge the density of the foam. When using a machine to do the job for you it all too easy to over whisk and collapse the foam. Years ago, the curved base bowl used for beating whites were made of copper combined with a bulbus whisk known as a balloon whisk. Today we still use the whisk but not the copper bowl, stainless steel is the material of choice. Not only is it easier to clean but the action of vigorously beating the white could remove tiny amounts of copper into the food which is poisonous to us.
So, in the kitchen the whole egg is useful to us as a component in cakes and pasties -understand pasty. But it’s the flexibility of the individual parts of the egg that excite us.
In practical terms use egg yolks to enrich, bind and thicken a preparation. We use egg white to lighten by adding air, like a souffle or strengthen a preparation by adding more protein, like a chicken mousseline. Think of a crème brulee, soft, rich, texture eaten out of a container- we use egg yolks. For a crème caramel, a bit firmer, not as rich and sitting up proudly we use whole egg. The addition of the white gives the dessert the ability to support itself.
The next time you are using egg in a dish or baking try to work out what the egg is providing and how best to maximise on the affect it brings. You may be able to improve the result and begin creating new ideas.
Enjoy life.
John