How does one boil an egg? Why should you eat them and what nutrients do they contain? We started thinking about this on the day my graduate daughter phoned to ask the question and so we began chatting about it.  Horrified because we thought that most of us simply used instinct, we thought about it and realised how profound a question it was. A year ago, a book by Hervé This appeared on bookshelves all over the world and opened the door to the science of  molecular gastronomy. Now everyone can understand why and how

cooking processes work and why certain things happen they way the do in a kitchen. The egg consists, roughly, of the shell, the albumin and the yolk and  all three of them need to be taken into account when boiling the perfect egg.

THE SHELL

• The shell of a hen’s egg makes up between 9 – 12% of the total weight of the egg (depending on the size of the egg, of course).
• This shell consists of 94% calcium carbonate flecked with magnesium carbonate, calcium phosphate, a little protein and traces of other organic matter.
• The hen’s diet, naturally, affects the strength of the shell but so does the egg size, thus there is a fixed amount of shell cover available so that the shell becomes thinner, the larger the egg.
• Then there is the matter of the pores – between 7,000 and 17,000 miniscule pores are found over the surface of the shell and as the egg ages, moisture and carbon dioxide diffuses out whilst air diffuses in through the pores causing the shell to grow and the net mass of the shell to decrease.
• The shell is covered with cuticle which, in blocking the pores, helps to preserve the freshness and prevent microbial contamination of the contents.
• In this lies a warning to those of you that have this thing about madly washing everything in sight – you’re nuts.
• Good quality eggs simply musn’t be washed until seconds before you use them for logical reasons (and if the reasons aren’t logical at this point, start at the top and read again).
• The breed of chicken will determine the colour of the shell and therefore, for example, the brown-shelled eggs should be more expensive as they come from the larger breeds that cost more to feed thus producing more expensive egg.
• To those people that have noticed that mass-market eggs have thinner shells – you are all right – these poor hens not only live horrendous lives, they also get sub standard feed as the proportion of “grit” (a calcium supplement) in their feed has been reduced because it’s too expensive to transport – for this reason the shells are cracking easily.
• Eggs need to be checked very carefully when purchasing – not all cracks are immediately visible to the naked eye.
• Pricking an egg with a needle at the blunt end of the egg will not stop the thing from cracking when you boil it, rather add vinegar or salt to the water so that any liquid coming out of a small crack will coagulate immediately and plug the offending hole.

THE ALBUMEN

• Accounts for 67% of the eggs weight and consists of four opalescent layers, alternatively thick and thin.
• A fresh egg white has a pH of 7,6 to 7,9 and is cloudy (opalescent) because of the presence of carbon dioxide.
• As the egg gets older, the carbon dioxide escapes causing the pH to go up.
• Aging also causes the white to become thinner as the protein changes in character and if you sit down quietly and think about it, it all makes perfect sense.
• To see what I mean, take an old egg and very fresh egg and break both into a clean plate – you’ll notice that the fresh one is firm and the older one spreads out – it sort of flops flat.
• Fresh egg whites coagulate at 62 – 65 C but when eggs are older, the coagulation temperatures become lower and so, fresh eggs take longer to cook than old eggs.

THE YOLK

• It makes up 33% of the liquid weight of the egg and contains all the fat but less than half of the protein.
• As far as vitamins go, with the exception of riboflavin and niacin the yolk contains more vitamins than the white.
• All the vitamins A, D and E are found in the yolk of the egg – of special interest is the fact that the yolk is amongst a very limited number of foods available to us that contains naturally occurring Vitamin D, so important for our brothers and sisters of the Northern Hemisphere.
• The minerals – phosphorus, manganese, iron, iodine, copper and calcium are found chiefly in the yolk and all the zinc in the egg is found here as well.
• A yolk consists of 250 KJ of energy.
• Egg yolks have a pH of 6,0 and it remains constant as the eggs age, with little carbon dioxide loss.
• Coagulation starts at 65 – 70 centigrade.

SOFT BOILED EGGS

• Choose the pot so that it will be big enough to fit the number of eggs that you’d like to cook snugly, or choose a bigger pot and place the eggs on the bottom in a single layer.
• Should you have two or three layers of eggs piled in a small pot, they would probably cook unevenly.
• Pour enough water into the pot to cover the eggs with at least 3 cm of water.
• Bring the water to the boil and submerge the eggs in boiling water.
• This is best accomplished using a spoon, placing the eggs on the spoon, individually and lowering them into the boiling water.
• For sensitive hands, use kitchen gloves
• After the eggs are in the pot, turn down heat to a light simmer.
• Timing is vital as with soft boiled eggs, timing is crucial.
• The recommended range of times is between three and four and a half minutes.
• For people living in higher altitudes a little extra time is necessary because water boils at a lower temperature here than at sea level.
• Should you be in a hurry and not be able to wait for the eggs to warm up to room temperature, cook the eggs for at least 4,5 minutes and only then check to see whether they are done.

Too soft-boiled

If your soft-boiled eggs aren’t entirely cooked, don’t fret.

• Simply fix this by cracking and emptying them into a small sturdy, oven-safe ceramic bowls – if they aren’t quite done, take the pot of hot water and pour out some water, so that the water level is less than the height of the bowl.
• Place the bowl with the undercooked eggs directly on the bottom of the saucepan, and put all of this back on the stove burner.
• Another 30 to 60 seconds of cooking and the eggs will be cooked to perfection.

STEAMED EGGS

• Our favourite method of boiling eggs is to steam them.
• Use about 1 cm depth of boiling water in a pot with a tight fitting lid.
• Put the eggs on the bottom of the pot to reduce bumping and hopefully the possibility of cracking.
• Because only a small amount of water needs to be boiled, the method also saves time and energy.
• Alternatively,  remove the eggs from their shells and pop into small baking dishes, cover with a little cream or creamy stock and place the dishes over boiling water, cover and simmer until set.

THE NUTRIENTS IN EGGS