by Tom Stobart
The shell of a hen’s egg is usually under 0.5 mm thick (1/50 in) and weighs roughly one-eighth of the total weight of the egg; it is made up largely of calcium carbonate. The strength of the shell varies with breed and with the hen’s food and health. Battery hens often lay eggs with fragile shells. Colour may vary from dead white through cream to brown, even speckled. Brown eggs are more expensive than white eggs because they look nice, but apart from their use as boiled eggs in the shell they have only one advantage to offset their greater price – they have slightly less porous shells and so may possibly keep longer. The shells of all eggs have to be porous to some extent, to allow air to enter for the developing chick (which, we sometimes forget, was what the egg was designed for).This porosity means that aromas can enter (an advantage only if you are keeping eggs in a bag with truffles), as can micro-organisms. One in ten eggs contains harmless bacteria even when freshly laid, but less harmless kinds can get in subsequently; especially when the shell is dirty and wet. That is why, if an egg has to be washed, it should be used at once.
Lining the shell is a flexible double membrane, the two layers of which are virtually stuck together except at the large end of the egg where they separate to enclose an air space. This pocket grows bigger as the egg gets older, until after some days it gets big enough to cause the egg to float, or at least for the large end to lift off the bottom of a basin of water. It is on this that the tests for freshness are based.
The white of an egg is layered, the outer layer being more watery than the inner. Egg white consists of on average 9% protein and 88% water, and makes up a little over half the total weight of the egg. Egg white mixes with water when raw, but coagulates when heated to about 70°C (160°F) and becomes very hard and indigestible when heated to still higher temperatures. However, like meat protein, it becomes soft again when boiled for several hours, as in Chinese tea-leaf eggs and the hamine eggs of Egypt, for which see Claudia Roden’s A Book of Middle Eastern Food (Penguin).
Tea-leaf eggs are boiled for 2-3 hours in water containing tea leaves and star anise, with various other additions – salt, monosodium glutamate, soy sauce, sugar, onion, etc. – according to the recipe. These eggs have pale brown marbling which is produced by cracking the shell after the first 20-30 minutes cooking, a smoother tender texture which comes from the long boiling, and flavour that has seeped in from the anise and other substances in the water. Tea-leaf eggs are served cold as horsd’oeuvre or with salads.
Egg white dries into a hard, shiny coat – something like varnish – and can, of course, be whipped to a firm froth (see whipping). In stale eggs, the white becomes watery.
The yolk is contained in a sac – the vitelline membrane – and is suspended at either end by a stringy chalaza or balancer. The chalaza is attached to the yolk so firmly that it clings to it as a tail when the egg is separated. Yolk makes up about a third of the weight of an egg and consists of 16% protein, 51% water and 30% fat. It is the most nutritious part of the egg. The colour of the yolk depends upon the food eaten by the hen.
Blemishes in commercially-packed eggs are rare because they have been examined against a light (candled) at the packing station. Blood spots, unless very large, can be ignored as they merely indicate that a tiny blood vessel was ruptured while the egg was being formed. Commercially-produced eggs are rarely fertile, but in fertile eggs a minute spot can be seen on the upper surface of the yolk. This is the germ from which the chick would develop if the egg were to be incubated. Some say that fertile eggs are better than infertile ones, an opinion not shared by vegetarians, who prefer unfertilized eggs because eating them does not involve taking life. Battery produced eggs are avoided by many people because they lack flavour and possibly some of the more subtle nutrient qualities of free-range eggs, but here the question of price is also involved.
There is, however, universal agreement that an egg is best when fresh. A simple test is to put the egg in water. If it lies flat on its side on the bottom, it is fresh; if it shows a tendency to get up at the broad end, eventually standing vertical, it is stale; if it floats under water, it is 2-3 weeks old; if it floats on the surface, it may have been laid for several months and be bad. A more sensitive test is to put the egg into 12% salt solution (which can be kept in a bottle and used many times). Fresh eggs will lie flat on the bottom, but they will get up at the broad end after only 2-3 days and will eventually hang suspended in balance when they have the same specific gravity as the brine.
At only four days, the eggs will come to the surface and float vertically with the broad end peeping out; thereafter they will float higher each day. After fifteen days, the egg will topple and lie flat, floating on the surface of the brine. This test is depressing. Most of the eggs you buy in the shops are at least a week old, good but not excellent. When broken on to a flat surface, really fresh eggs stand up in a convex mound, but as they get older the convexity decreases. In really stale eggs, the white is watery and the vitelline membrane so weakened that yolk and white mix. Such eggs may still be tolerable in cakes but are not much use for anything else.
The average egg weighs about 60 g (2 oz), large eggs 70 g (2¾ oz) or more, and small ones go down to 45 g (1½ oz); even smaller are pullet’s eggs. In the poorer countries, eggs are almost always smaller than the European or American average and allowances should be made for this when following recipes from such countries.
EEC egg sizes are:
Size 1 over 70 g
2 65-70 g
3 60-65 g
4 55-60 g
5 50-55 g
6 45-50 g
7 under 45 g
These do not correspond exactly to the grades of the previous British system, in which the main sizes were large (over 62 g or 2 oz), standard (over 53 g or 1⅞ oz), medium (over 46 g or 1⅝ oz) and small (under 46 g or 1⅝ oz).
Coagulation. The white of an egg coagulates at about 60-65°C (140-149°F) and the yolk at the slightly higher temperature of 62-70°C (144-158°F). When yolk and white are mixed the coagulation takes place at about 69°C (156°F).The coagulation temperature is even higher when milk, water or sugar are added, so that custard coagulates at around 80-85°C (175-185°F).Those making custard or sauces thickened with eggs may also find it useful to know that coagulation will begin at a lower temperature – though only slightly so – when the temperature is raised slowly than it does when the temperature is raised fast, and that while the custard is thickening the temperature in it does not continue to rise because – put simply – heat is used up in the thickening process. Once the temperature starts to rise again it means that coagulation is completed. If the heating is continued, the sauce will curdle (at around 88°C/190°F). Of course, the sauce must be stirred because otherwise it will set solid, like baked custard.
Smoked eggs from China are lightly hard-boiled eggs which have been shelled, marinated and smoked. They are served as hors d’oeuvre or as part of a cold plate. A similar result can be obtained by marinating hard-boiled eggs in soy sauce seasoned with smoked salt and slightly sweetened with sugar.
Preserving eggs. You need to use new-laid, clean eggs. Even so, you can expect one in ten to be contaminated by bacteria. This means that a few may go off, though they will not be dangerous, only unpleasant. Preserved eggs should always be broken one at a time into a separate container. There are many methods of preservation to choose from, some old fashioned, as follows:
Preserving eggs in lime
Make a mixture of 200-250 g (7-9 oz) slaked lime, 30-40 g (1-1½ oz) salt and 1 teaspoon cream of tartar to each 1 It (1¾ pt) of water. Boil the mixture, but do not put the eggs in until it is stone cold. Keep in a cold cellar.
Preserving Eggs in Waterglass
Waterglass is a clear, syrupy substance, which, as bought, is a 50% solution of sodium silicate in water. Prepare according to the instructions on the tin. If there are none, try diluting it with 5-10 times the volume of water.
A 3% solution of sodium silicate is enough to preserve egg
s, but 5% is really safe. Stronger solutions make the eggs taste nasty. Eggs may be dipped in waterglass, allowed to dry and stored in dry sawdust to prevent breakage. (This may be a convenient method for yachtsmen on a long voyage.) However, it is better and more usual to leave the eggs in the liquid. They must be kept between 7°C (45°F) and freezing (but not below) – e.g. in a cold cellar. If the temperature rises, even for a few hours, deterioration is rapid. Waterglass eggs should be well rinsed in fresh water before use. It is interesting to know that although the purpose of storing eggs is usually to preserve them from the spring (when there may be too many) to the autumn and winter (when the hens moult and stop laying), they can, if necessary, be kept for very much longer periods. At six months, waterglass eggs are merely a bit stale but good for most purposes. At a year, the extra storage time can scarcely be noticed. At two years, it is obvious; at three, the white starts to turn pink and become very watery, and at four years...! Nevertheless, the eggs are still quite edible, the white will still coagulate when heated, and the taste is not unpleasant.
The effect of lime or waterglass is to seal the pores in the eggshell. Other methods of doing this are also effective. Shells may be rubbed with clarified butter, dipped in molten wax or painted with gum arabic; the eggs are then stored in bone-dry sawdust, bran, charcoal or ashes. Another way is simply to pack the eggs tightly in dry salt. (They are packed thus to exclude air.) An interesting way – which relies on a thin coagulated layer – is to plunge the eggs for 20 seconds into boiling water before drying and packing them in dry bran. Some people even store eggs for shorter periods by wrapping in greaseproof paper.
Eggs will stay good for a long time if they are chilled – stored at 6°C (43°F) but not below this.
Eggs cannot be frozen in the shell. To freeze eggs, first crack them, then either separate the yolks and whites or stir the two together. Mix with either salt or sugar (according to the purpose for which they will later be used) at the rate of 1 teaspoon per dozen eggs and freeze as usual in containers. Frozen white does not return to normal after unfreezing but it can be whipped and used in cooking.
Dried egg. The idea of drying eggs was thought up in the 19th century, but was first successfully undertaken by German engineers in China in the present one. China was the principal source of dried egg for the world until the 1930s, when production became viable in the US and Britain. Dried egg production reached a peak during World War II, and immediately afterwards dropped sharply, no doubt because of a general aversion to anything to do with rationing and war-time shortages. Since then, intensive research has improved the product, and the commercial use of dried egg has grown steadily. Eggs to be dried may be separated into yolk and white or mixed up and dried whole. They are generally spray-dried and pasteurized. Drying causes little or no loss to the nutritional value of eggs, but the flavour does alter. However, dried eggs usually taste much the same as fresh eggs in custards or scrambled. The whipping qualities which are largely lost in drying can be restored by the addition of certain chemical compounds and carbohydrates such as sugar. Dried-egg products are principally used in the baking industry and in sweet manufacture (e.g. in the fondant filling for chocolates). Dried egg is now of little interest outside the food industry except to the nostalgia prone who want to follow wartime recipes and to campers in remote places.
Duck eggs have a chalky white or very pale blue shell. Many people prefer them to hen eggs for flavour. They have a distinctive taste, and a somewhat gelatinous, blue-tinted white. Some varieties of duck beat all records for egg laying – almost one a day for the whole year – but the eggs are not so popular as hen’s, because ducks, being messy and none too disciplined, may drop their eggs in dirty and contaminated places. Not all producers are fussy about what they sell, and so duck eggs have a bad reputation with the general public. Occasionally, they have become infected with Salmonella bacteria and have caused food poisoning.
However, duck eggs are very popular in the Far East and are the basis for the famous Chinese thousand year eggs (trúng-den).They are in fact ready to eat in something under two months and become solid by a maturation process – ripened as if they were cheese. The egg inside is variable in colour from greenish yellow to malachite green and black, usually in concentric rings, following the pattern of the original egg layers. The texture is smooth and creamy, the flavour original and unlike anything else, although overtones of bad egg are detectable when they are first broached. Thousand year eggs are served at the start of a meal, usually quartered and served as an appetizer, perhaps with lime and fresh ginger. They can be bought at shops which specialize in Chinese foods, but it is probably better to be introduced to them by Chinese friends who know what a good bad egg should taste like.
Salted eggs are another Chinese speciality. These duck eggs preserved in strong brine may be bought from Chinese provision shops and are very salty. Keep them in a refrigerator.
Thousand Year Eggs
For a couple of dozen absolutely clean and fresh duck eggs, mix up a paste of 120 g (4½ oz) each of salt and wood ash, and 100 g (3½ oz) slaked lime, with about ½ It (1 pt) of water. Wash the eggs in hot water and roll each one in a handful of the ‘paste’, coating each about 1 cm (½ in) thick. Roll each coated egg in chaff to give it a non-stick coating. Pile the eggs in a crack and cover with a lid. After 3 days turn the pile over, eggs on top to the bottom, and do this every 3 days for 15 days. After that, seal the jar and leave it for a month. The eggs are now ready to eat. Remove paste and shell, and cut the cheesy egg into pieces for serving.
Goose eggs are something like a very large duck egg, but rather milder in flavour.
Guinea-fowl eggs look something like small hen eggs and are of excellent quality with a mild flavour.
Black-headed gull eggs have now replaced plover eggs. They have a somewhat similar appearance (brownish olive-green with dark brown spots) and are not much larger. They are good, but not quite equal to plover eggs, like which they are usually eaten hard boiled. The eggs of the herring gull and other seabirds (e.g. the gannet) were – and still are in places – harvested off the cliffs. I remember from my childhood the egg-gatherers arriving yearly with ropes at the great red sandstone cliffs of St Bees Head. After gathering eggs, they boiled great buckets of them on the beach below. This was a wasteful process, as many of the eggs already had chicks half developed inside them. The eggs of herring gulls are tolerable if fresh, though stronger than those of the black-headed gull. In the past, they were an essential food to many islanders, but their collection is no longer necessary, and it is hardly worth risking your neck to get them.
Moorhen eggs. The eggs of this common bird are good and were once much taken by country people. Provided eggs are removed quietly, a few at a time, moorhens will go on laying for many weeks.
Ostrich eggs are available only in South Africa and other places where ostriches are farmed. These enormous eggs are equivalent to one to two dozen hen eggs. They have a rather eggy taste, but are excellent for cooking and are sometimes sold as dried egg.
Partridge and pheasant eggs are sometimes available where game birds are bred. They are smaller than hen eggs and are excellent.
Penguin eggs. Penguins nest in huge rookeries, so the eggs just beg to be gathered and eaten. Eggs of the Cape or jackass penguin are officially taken in modest numbers from the islands off Cape Province, in South Africa. They fetch a high price. Penguin eggs are peculiar, in that the whites remain clear even when they are hard boiled (so they look like eyes on the plate), but since they are usually eaten well laced with Worcestershire sauce, I cannot help feeling that motives for eating them are more snobbish than gastronomic.
Pigeon eggs. Small and delicious, pinkish-white eggs, most often served hard boiled. As the author of the Time-Life publication The Cooking of China says, it is something of a chore to eat a hard boiled pigeon’s egg with chopsticks, and anyone who has mastered the art can justly claim to be an expert.
Plover eggs. In the past, th
ese were considered a great delicacy, and there are recipes for them, not only hard boiled, but also cooked in other ways. Unfortunately, the population of plovers has declined (mainly because of changes in agricultural methods), and it is now against the law to gather the eggs in Britain. Plovers must have been very plentiful in the past – because their nests are hard to find – and gathering was done by professionals with the care necessary to induce the birds to go on laying over a period and subsequently to hatch their normal setting.
Quail eggs. Very small eggs, usually eaten hard boiled. They have become available in recent years as a by-product of quail farming. For a long time, they have been highly regarded as a delicacy in the Far East.
Turkey eggs. Large, brown, spotted eggs of excellent quality. The smaller eggs of young birds – paler than those of older birds – are good boiled, the others are used for cooking. They taste rather like hen eggs and make splendid omelettes.
[Egg – French: oeuf German: Ei Italian: uovo Spanish: huevo]
EGUSI MELON. See marrow (Cucumeropsis edulis).
EGYPTIAN PEA. See chick pea.
EGYPTIAN BEAN. See chick pea, lablab bean.
ELDER. There are many species of elder in Europe, Asia and North America. Both the European common elder (Sambucus nigra) and the American elder (S. canadensis) have clusters of white flowers followed by dark purple to black berries. The flowers have a sickly smell, supposed to be like muscatel grapes, and bunches are stirred into wine, jam, jelly or stewed fruit (particularly gooseberries) to impart their aroma. The flowers are edible and may even be fried in batter. The berries are used for making wine, for colouring jellies, and for preserves, fruit soups and ketchup, they are also dried. However, their strange taste limits their use.