Caviar, which has a mystique surrounding it as a food of the very rich, is really just fish eggs. Its official definition will vary according to the country in which it is sold. In the United States and many other countries, caviar is the clean, salted fish eggs of any fish species. The label is required to list the particular type of fish serving as the caviar source.

In Europe, caviar is more narrowly defined by law as only the eggs of the Caspian Sea sturgeon. The most expensive, largest-grained caviar comes from the Beluga sturgeon. These fish can live for over 70 years and may grow to a length of 25 feet. Like chicken eggs, roe is very high in cholseterol – about 94 mg per tablespoon. It is also high in salt, but the best caviar is malassol, which in Russian means “little salt”. To protect the taste of caviar, it is served with a bone or shell spoon, because metal imparts an off-flavor. It is sometimes served on a neutral-tasting bread that has been toasted on one side, with the caviar being gently placed on the untoasted side.

• Emulsifying: Lecithin, found in egg yolks, keeps liquid compounds (like fat and water) from separating, thus thickening and stabilizing foods such as sauces and salad dressings.
• Binding: The high protein content in beaten eggs can act as an adhesive when cooked. Examples are egg use with breaded, fried foods and the addition of eggs to bind meatloaf.
• Foaming: Egg whites beaten into a foam increase their original volume six to eight times, and aerate and leaven food products such as souffles and meringues. The best egg-white foam is made from fresh eggs at room temperature.
• Interfering: Because they interfere with the formation of crystals (ice, sugar), eggs are used to create a smooth, velvety texture in ice cream and candy.
• Clarifying: Egg whites are used to make clear soups.

To preserve the egg’s texture, flavor, and color, it is best to keep cooking temperature low and the heating time short. Eggs can be prepared in a great variety of ways, using either dry-heat or moist-heat methods.

Dry-heat

• Fried, scrambled, omelets
• Baked (shirred, meringues, souffles)

Moist-heat

• Simmering
• Coddling
• Poaching
• Custards (stirred, baked)
• Microwaving

The chances of an egg being internally contaminated are relatively low, less than one in 10,000 commercial eggs. It is more common for contamination to occur during handling and preparation after the egg has been removed from its shell. Even so, eggs are an excellent breeding ground for microbial activity, and can become internally contaminated through a hen with a Salmonella enteritidis infection in her ovary or oviduct, or from absorbing bacteria through the pores. The latter can occur if the eggs are boiled and then cooled in the presence of infected water or an infected food handler. Externally, the eggs may also be exposed to Salmonella enteritidis by fecal contamination during egg laying. The Centers for Disease Control implicated eggs as the source for a high percentage of Salmonella enteritidis outbreaks, and there is an increasing possibility that Listeria monocytogenes, which can grow at refrigerator temperatures and has already been observed on whole eggs, may also contribute to future outbreaks. There are many precautions that can be taken to prevent foodborne illness from eggs.

• Use an egg separator rather than passing the yolk back and forth between the two shell halves.
• Always store eggs in the refrigerator, never at room temperature. Meringue-covered pies and other egg-containing foods should be refrigerated until served.
• Raw eggs should never be consumed as this is especially the case for the very young, elderly, or immune-compromised.
• Use only pasteurized eggs for food items in which eggs are only lightly cooked or not at all, such as Caesar salad, uncooked hollandaise or bearnaise sauce, and homemade mayonnaise, eggnog, ice cream, etc.
• Do not add raw egg to already scrambled eggs, a practice sometimes used in food service operations to increase the moisture content of dried scrambled eggs.
• Cook eggs until no visible liquid egg remains, especially when preparing French toast, scrambled eggs, poached eggs, and omelets.
• A knife inserted into baked egg dishes such as quiches, baked custards, and most casseroles should come out clean.
• Scrambled eggs should be held on cafeteria and buffet lines at appropriate temperatures.
• Be extra cautious when preparing lightly cooked egg dishes such as mousse, meringue, and other similar dishes, because they may not be sufficiently cooked to eliminate possible bacteria.
• All egg dishes should be heated to 145^oF (63^oC).

Drying eggs is a simple process. Whole eggs or separated yolks are spray-dried to create a fine powder, which is mixed with anti-caking substances to prevent clumping. Egg whites are dried in different ways to form granule, flake, or milled textures. Dried eggs sometimes brown due to the Maillard reaction, but this can be prevented by removing glucose from the eggs before drying with the aid of an enzyme (glucose oxidase) or by yeast fermentation. Once dried, eggs can be stored in the refrigerator for up to a year, but they must be kept in tightly closed containers to prevent the clumping that can result from moisture accumulation.

Dried eggs are used in food preparation by adding them to water or by sifting them with dry ingredients. One egg can be reconstituted by sprinkling 2 tablespoons plus 1.5 teaspoons of sifted egg powder over an equal amount of lukewarm water and beating until smooth. Combining 1/2 cup each of sifted egg powder and water produces the equivalent of three eggs. The mixtures should be used within five minutes.

Freezing a whole egg is not possible because it will crack under the expanding liquids, so food manufacturers solve this dilemma by breaking the eggs open at the processing plants where the contents are frozen whole (whites and yolk mixed together) or separated as whites or yolks. Prior to being frozen, the liquid whole eggs are usually pasteurized. Eggs whites by themselves denature if pasteurized, so prior to this process they are often combined with a small amount of lactic acid and aluminum sulfate. There are several drawbacks to using frozen pasteurized eggs: they are costly to freeze and keep frozen, they must be thawed, they are cumbersome to portion, and they have lowered functional quality.

Fortunately, separated egg whites are not adversely affected by freezing. Some commercially frozen egg whites have added stabilizers and whipping aids to improve their ability to form large, stable foams. For separated yolks, sugar, corn syrup, or salt is added to prevent them from becoming viscous and rubbery when thawed. Salt is used in frozen eggs only if they will be incorporated into sweet foods that will partially mask the salty taste. When freezing eggs at home, 1 tablespoon of sugar (corn syrup) or 1/2 teaspoon of salt is added for every cup of blended eggs. Raw egg whites can be frozen with no special measures taken.

Eggs begin to deteriorate as soon as they are laid and lose quality very rapidly at room temperature. To ensure the freshness of whole or liquid eggs, they may be refrigerated, frozen, or dried.

Storing in the Refrigerator

Whole Eggs. Several signs distinguish fresh eggs from those that have aged. Changes in proteins over time cause egg whites to thin. Fresh eggs also have more prominent, viscous chalazae on either side of the yolk than older eggs. In the process of aging, the vitelline membrane weakens and the yolk migrates or breaks. The size of an egg’s air cell provides another indication of its age. The air cell gap between the membranes increases in size as the egg ages because moisture and carbon dioxide escape through the porous shell.

Proper refrigeration of eggs helps to delay these changes and protects them from microbial growth, thus helping to maintain their quality. Many home refrigerators have built-in egg containers, but eggs retain their moisture better and keep longer if stored in the carton. Eggs should sit in the carton with their large ends up to prevent the air cell from moving toward the yolk. Washing eggs is not recommended, because this will remove the oil coating applied by the processor to prevent microbial growth and moisture loss.

Refrigerated whole eggs should stay fresh for about a month. Separated egg yolks may be stored under water in the refrigerator, but should be used within two days. Egg whites kept tightly covered in a glass container will last up to four days.

Storage Eggs. Restaurants, food service institutions, and other food manufacturers must be especially careful about storing eggs, because they purchase such large quantities. Storage eggs, used by commercial food service establishments, are usually used within a month, but can be stored for up to six months. They are not available at the retail level. The coating of oil or plastic prevents microbial invasion and any loss of moisture or carbon dioxide.

Liquid Pasteurized Eggs. Another type of egg product available to commercial outlets is refrigerated liquid eggs that have been pasteurized. Typical processed food products that may incorporate pasteurized liquid egg whites include baked goods, candies, and chilled or frozen desserts. The USDA regulations require that all liquid, frozen, or dried eggs be pasteurized or otherwise treated to protect against Salmonella. After being pasteurized, the advantages of liquid eggs over whole eggs or even frozen egg blends are convenience, consistent quality, microbial safety, and costs savings in terms of space, labor, and freezing.

Microwave Fried Eggs. A browning dish is required to fry an egg in a microwave, and should be preheated on full power for two minutes, plus one additional minute for each egg being fried. About 1/2 teaspoon or less of fat per egg is melted in the dish before adding the cracked eggs from a bowl into the dish. The yolk membrane is punctured, and the dish is covered with plastic wrap, then microwaved on high for 45 seconds per egg or until the desired doneness is reached.

Microwave Shirred Eggs. Shirred eggs are cooked in individual containers and are ideal for cooking in a microwave oven. The egg is placed in a custard dish, the yolk is punctured, the dish covered, and the egg is heated on medium for 45 to 60 seconds. It should be rotated a quarter turn at the half-minute mark.

Microwave Scrambled Eggs. Before scrambling, 1 teaspoon of butter is melted in a 2 cup glass measure by setting the microwave very briefly on high. The beaten eggs are placed in the measuring cup and microwaved on high for 20 seconds. The egg mixture is then stirred, and the heating and stirring process is repeated one or two more times. Microwaving is completed when the eggs are just past the runny stage. They should be allowed to stand one or two minutes if a firmer set is desired.

Microwave Poached Eggs. To poach an egg, 1/4 cup of water, with a dash of vinegar and salt, is heated to a boil in a custard dish or 1-cup glass measure. The egg is dropped into the hot water, and the yolk is pierced with a toothpick. The dish is partially covered with plastic wrap and then heated at 50 percent power for about 1 minute, plus or minus fifteen seconds. Allowing the cup to stand two to three minutes and gently shaking back and forth helps to set the egg whites.

Microwave Omelet. Omelets can be prepared in the microwave by using a browning dish or 9-inch pie plate. Enough butter is added to slightly coat the bottom of the dish. It is melted on high and then spread evenly by tilting the container. The combined eggs, liquid, and seasonings are then poured into the container, covered with plastic wrap, and cooked on medium for two to three and a half minutes, or until the omelet is almost set. After removing the omelet from the oven, any fillers are added, and the omelet is folded over with a spatula. Puffy omelets are prepared in the same manner. An omelet cooked in a microwave will not brown unless a browning dish is used.

Microwave Quiche. A quiche dish or pie shell is filled with cooked vegetable and/or meat ingredients. Cream (preheated, unlike the cream in conventionally cooked quiches) is added to the beaten eggs, and the egg mixture is then poured over the vegetables and baked according to the manufacturer’s guidelines.

Custards are mixtures of milk and/or cream, sweeteners (sugar, honey), flavorings (vanilla, nutmeg, etc), and eggs or egg yolks. Custards are thickened by the coagulation of egg proteins during cooking. These egg proteins denature when heated and recombine to form a network that sets or coagulates, at the right temperature, to form the solid gel of a custard. All custard dishes are very susceptible to microbial contamination and should be covered and refrigerated as soon as possible after preparation.

Sweet custards are served as desserts in the form of puddings or as fillings for éclairs and pies. Savory (non-sweet) custards are used for dishes such as quiches. A popular quiche made with bacon and Swiss cheese is known as quiche Lorraine. Custards are further distinguished by their preparation method: stirred or baked.

Stirred Custard (Soft Custard or Custard Sauce). The ingredients of this custard are stirred while being heated on the range over low heat or in a double boiler. The mixture retains a smooth, creamy, fluid consistency. Stirred custard is often eaten as a pudding; however, it may provide the base for many frozen desserts, be served as a sauce for cake, fruit, and other desserts, or be used to replace eggnog. The repeated stirring prevents the formation of a gel, so the custard mixture thickens instead of gels.

Baked Custard. Unlike stirred custards, which are prepared with moist heat, baked custards are an example of dry-heat preparation. Both types of custards begin with the same ingredients, but are simply heated differently. Baked custard mixes are poured into ungreased custard cups that are placed in the oven, usually in a water bath (bain marie), where they sit undisturbed and gel during baking. A water bath is made by filling a large, low-side pan with 1 inch of hot water, into which are placed the cups containing the custard mix. The layer of water insulates the cups and prevents the outside of the custard from cooking to completion before the inside has had a chance to coagulate.

The internal temperature of custards should never be allowed to rise above the point of coagulation of the egg-liquid mixtures. Overheating causes the egg proteins to shrink, allowing liquid to be released from the egg and producing a product with a curdled, weepy, porous appearance. Another problem with baked custards is that they tend to have a runny texture, which makes then unsuitable for making solid pie fillings. As a result, custards to be used as pie fillings are often thickened with starch in the form of cornstarch or flour.

Custards should be baked at 350^oF(177^oC) until a knife inserted in the middle of the cup comes out clean – about 23 to 25 minutes for custard cups and 35 to 40 minutes for a casserole-size dish. Just before complete doneness is reached, the custard is immediately removed from the oven and placed on a rack. Some additional cooking will inevitably occur during cooling, but can be minimized by using a cooling rack. Should the custard be overcooked, the cups can be set in ice water to stop further coagulation. Undercooking should likewise be avoided, because it will prevent the custard from setting properly.

Poaching. Eggs are poached by being cracked and simmered in enough water to cover the egg by at least twice its depth. Fresh USDA Grade AA eggs are best to use for poaching, because the whites are firmer and less likely to spread out in the water and create “streamers”, floating strands of partially cooked egg whites. Salt (1/2 teaspoon per cup) and/or vinegar (1 teaspoon per cup) may be added to the water to speed coagulation and help to maintain a compact, oval shape of the egg. On the other hand, salt of vinegar will give the cooked egg a shinier, tougher, and perhaps more shriveled surface than one cooked in plain water. Poached eggs are cooked for three to five minutes, removed with a slotted spoon, drained, trimmed of any streamers, and served immediately. The well-poached egg should have a firm yolk and compact white.

Simmering. Simmering temperatures are used to prepare eggs that are hard or soft “boiled”, coddled, poached, incorporated into soft custards, or microwaved.

“Boiling”. Although the term “hard-boiled eggs” is commonly used, eggs should actually be simmered and never boiled, because they will become tough and rubbery if so treated. The high heat of boiling also transforms the iron in the egg yolk into ferrous sulfide, causing the greenish-black color and unpleasant flavor found in the yolk of overly hard-cooked eggs.

Simmering hard-cooked eggs makes them prone to cracking, but this can be avoided by first warming eggs to room temperature in a bowl of warm water. Eggs crack because the pressure created by fast-heating water pops the shell. Another way to reduce the chances of cracking is to push a sterilized pin or needle through the large end of the shell where the air cell is located. To reduce cracking still further, a spoon or other utensil may be used to place the eggs gently in the water.

There are two methods for hard-cooking eggs: hot start and cold start. Each has advantages and disadvantages; each produces acceptable products. The benefits of using the hot-start method are greater temperature control, eggs that are easier to peel, and a shorter total cooking time. A drawback is that lowering the eggs into boiling water may cause them to crack. The advantages to the cold-start method are that less attention to the process is required, the eggs are easier to add to the water, and they are less likely to break. On the other hand, starting eggs out in cold water may cause the egg white by the shell’s surface to be more rubbery, and there is a greater chance of a greenish tint forming on the egg white.

In the hot-start method, the water is heated to boiling and then the eggs are completely immersed in the boiling water. The heat is immediately reduced to simmer, and the eggs are cooked for 3 to 15 minutes, depending on the desired doneness:

• Soft (3 to 4 minutes)
• Medium (5 to 7 minutes)
• Hard (12 to 15 minutes)

The cooked eggs are drained and then rinsed under cold running water to stop further cooking from residual heat. The extreme temperature change from hot to cold also helps loosen the egg’s membrane from the shell, making it easier to peel. To further ease peeling, the first crack should be made at the air cell located at the larger end of the egg, and then the egg rolled gently between the hands to break the shell all over. Peeling under cold running water also makes the job easier. Fresher eggs are harder to peel because the air cell is smaller and the membrane is tight against the cell wall. Although the larger air cell and higher pH of older eggs makes them easier to peel, they also tend to break more easily during heating.

In the cold-start method, the eggs are placed in a saucepan with enough cold water to cover them by at least an inch. The water is brought to a boil, immediately lowered to a simmer, and the eggs are then cooked to order:

• Soft (1 minute)
• Medium (3 to 5 minutes)
• Hard (10 minutes)

Another way to prepare hard-cooked eggs from a cold start is to remove the pan from the heat as soon as the water boils, cover it tightly, and let it stand for 20 minutes. Cold-start eggs are less likely to crack during cooking. Once cooked, eggs can be cut into slices or wedges. Dipping the knife in hot water before slicing keeps the hard-cooked eggs from falling apart. One way to tell a shelled hard-cooked egg from a raw one is to spin the egg on its side. A smoothly spinning egg is hard cooked, while one that wobbles out of balance is not.