Egg functions

As with most ingredients these days, an egg is no longer merely an egg. Egg options abound for bakers who must decide between powdered or liquid, free-range or cage-free, white or brown shell, and what type of fortification they desire. Some bakers even are opting for specialty eggs, custom made to their unique demands.

Egg functions
In baked products, eggs provide a number of functions. They offer richness and structure, coagulation, foaming, water holding properties, act as an emulsifier, and thicken icings and fillings. An egg wash can be used to brown the crust in specialty breads, provide texture and mouthfeel in muffins, add protein to health bars, or add volume through aeration in cakes.

Eggs also work as a substitute in gluten-free products. “Albumen, the protein found in eggs, is a complete protein that can be substituted for gluten to maintain a high protein content in product formulations,” says Marcia Greenblum, registered dietitian, and director, Nutrition and Food Safety Education, Egg Nutrition Center, Washington, D.C.

Eggs provide the basic structure for a baked product thanks to coagulation. When eggs are heated or beaten, they coagulate, or turn mixtures from a liquid to a semisolid or solid. Coagulation binds ingredients together, providing structure.

Custom-made eggs

“Coagulative properties come from both the egg white and the yolk,” says Glenn Froning, Ph.D., professor emeritus, Food Science and Technology, University of Nebraska-Lincoln, and food technology advisor, American Egg Board. “High gel egg white is produced for some food applications to [achieve] higher coagulative properties.” Egg white proteins primarily provide foaming properties. The emulsification properties are provided by the lipoproteins and phospholipids found in the yolk. An egg yolk's yellow color results from xanthophyll pigments, which are influenced by the bird's diet. “Feed ingredients, such as yellow corn, alfalfa meal and marigold, increase the yellow color. Some processors are now fortifying rations with these pigments to increase lutein, which helps prevent macular degeneration,” Froning adds.

Custom-made eggs
Eggs can be altered or custom produced to fit a nutritional profile, yolk color, shell color, flavor or form. “You can manipulate an egg in a variety of ways. We see the egg as a vector to deliver certain attributes,” says John Brunnquell, president/C.E.O./founder, Egg Innovations, Port Washington, Wis. “One customer might want a nutritionally modified organic egg powder and another might want a frozen egg yolk that is certified humane. We can alter the product to fit specific needs.” Egg Innovations sometimes designates facilities to individual companies and manages the birds within those facilities based on the company's needs, thereby producing eggs that match individual specifications.

Different yolk pigments or flavors, such as a more buttery flavor, are produced by monitoring the diet fed to the birds. A chicken that is fed flax will produce eggs that feature yolks fortified with omega-3 fatty acids.

Vegetarian eggs cater to lacto-ovo vegetarians, who eat eggs, cheese, yogurt and drink milk, but don't eat animal flesh, fish or shellfish. They are produced by birds that are not fed any animal by-products. These eggs also can be fortified with luteins, antioxidants and choline to appeal to nutrition conscious vegetarians.

Free-range organic eggs come from chickens fed organic grain and allowed to roam freely. “All our barns have about 16 to 20 openings in the building and the birds are free to move inside and out as much as they would like into a pasture area, depending on weather,” Brunnquell says. Cage-free eggs come from birds that are allowed to roam around the facility but remain indoors.

An egg's shell color is determined by the breed of chicken laying the egg. The earlobe color of a chicken is an indicator of what color egg they will produce. “Red-earlobed birds produce brown shells and white-earlobed birds produce white shells,” Brunnquell adds. “The white bird is a single comb white leghorn, and the dominant genetics for brown are Rhode Island red chickens. Organic eggs are brown because producers believe that is what consumers prefer, so we tend to use brown shell strains of genetics. We could easily use white shell strains, but have not.”

Health benefits, label claims
Eggs offer a range of vitamins, minerals and healthful fats, as well as just 70 calories. Egg yolks are one of the few foods that naturally contain vitamin D. Pregnant and lactating women, especially, can benefit from the choline content of eggs. “Choline, an essential nutrient needed for fetal brain and memory development and to prevent neural tube defects has been found to be inadequately consumed by adults of all ages in the United States,” Greenblum says.

“Research has revealed that choline plays key roles in proper nerve signaling, strengthening cell membranes, keeping homocysteine levels in check and preserving brain function in the elderly,” says Elisa Maloberti, director of egg product marketing, American Egg Board, Park Ridge, Ill. “Foods that contain at least 110 mg of choline per serving (or 20 percent of the daily value for choline based on 550 mg reference) may be labeled as an ‘excellent source of choline’ and foods with at least 55 mg choline per serving may be labeled as ‘good source of choline.’” A large egg contains about 180 mg of choline.

The protein in eggs is ideal for growing children and seniors who lose muscle mass as they age. High protein intake can help seniors maintain more of their muscle mass rather than increasing fat tissue deposits, a common part of aging associated with low protein intake. “The lutein and zeaxanthin, two carotenoids in eggs, can help prevent and slow the progression of cataracts and macular degeneration, which is the leading cause of blindness for seniors,” Greenblum says.

The cholesterol in eggs is a common consumer concern, and one that egg experts are working to reverse given more recent studies. “After 30 years of scientific research, there is still no research that shows egg consumption increases the risk of heart disease,” Greenblum says. “There is, however, a large body of evidence that has convinced organizations, such as the American Heart Association, to revise their dietary guidance to suggest that an egg a day can fit into a healthy diet.” A study done at Harvard's School of Medicine [JAMA April 21, 1999, Vol 281, (15) 1387-94], for example, examined the health outcomes of 38,000 men and 80,000 women who ate eggs as part of their diets during a 14-year period. Those who ate one egg daily had no greater heart disease rate than those who late less than one egg a week, Greenblum points out. “This finding has been seen in cultures all over the world and has led countries, such as Canada, Australia and New Zealand, to offer dietary guidance suggesting there is no reason to limit dietary cholesterol intake.”

The best form for your formula
 Eggs are available in a myriad of forms including powdered, frozen, fresh and liquid, all of which function equally well in baked products. Each form has its advantages, and experts agree, when formulated properly, there should be little variation in an end product, regardless of the egg form a baker chooses.

Fresh eggs and liquid eggs are convenient because they are quick and ready to use, while dried eggs offer a long shelf life, stability, are easy to mix and can be stored with other dry ingredients.

Dry egg products usually are produced by spray drying, or some egg white is dried on trays to produce a flake or granular form. Glucose is removed before the egg white is dried, which allows for excellent storage stability, according to the American Egg Board. “In an atmosphere-controlled environment, 60°F to 70°F (16°C to 21°C) with normal humidity, powdered egg has a shelf life of 12 months to 18 months,” Brunnquell says. Powdered egg is economical, especially for bakers who are having the ingredient shipped.

Frozen egg would be an inconvenient option for a baker seeking a ready-to-use product. On the other hand, a baker interested in lower costs, who has freezer space, is using a local supplier and wants a longer shelf life, might benefit most from frozen eggs, which can last for 12 months. Depending on volume, frozen eggs also are cheaper on a per unit basis than fresh products, Brunnquell says. Once thawed, frozen eggs cannot be refrozen and should be refrigerated at the coldest possible temperature (40°F to 45°F/4°C to 7°C), for no more than three days, according to the American Egg Board.
By contrast, shell eggs last 30 to 45 days and liquid eggs last about 15 days.

"While freezing or drying eggs may slightly change the nutritional composition of eggs, the beneficial nutrients are minimally affected. Protein, lutein and choline are all stable in the freezing and drying processes,” says Hilary Thesmar, Ph.D., director, food safety programs, Egg Nutrition Center, Washington, D.C. Pasteurization also has a very minimal effect on the nutritional composition of eggs, and pasteurized eggs are widely used in the industry for emulsification, she adds. In addition, the beneficial nutrients in eggs withstand the baking process and are therefore all present in baked products containing eggs.

“Pasteurization speaks squarely to food safety. In the United States, anything broken open in the egg industry-so anything other than shell form-will be pasteurized. The reason is the yolk is so nutrient-rich it could sustain bacteria, and the pasteurization is the food safety process where you kill any bacteria,” Brunnquell says.

When a baker switches from one egg product to another, formulation changes are necessary. “It is really a matter of how a company is structured and how the formulations are written, but we have worked with companies who said, ‘Now we are doing liquid, and we want to go to powder.’ We sit down with whoever has written the particular [formula] because now instead of putting 20 gal. [of liquid egg] in a batch, you might put 2 lb. [of powdered egg],” Brunnquell says.

Other ingredients will need to be added as well. When switching from liquid to frozen-sugared yolk, for example, bakers must account for the sugar and possible blending changes, Froning says. Food scientists can help bakers achieve the desired finished product with the new egg form.

Egg Innovations has worked with companies switching from one egg form to another. “If you're making a meringue or a pie and you want the whites to really whip up, we can get a high whip white using a frozen egg white, a powder, etc., but the [formulas] will be slightly different on peripheral ingredients,” Brunnquell says.

“Egg products can be produced to definite specifications to assure consistent performance in formulations,” Thesmar says. “Most egg products are virtually indistinguishable from fresh eggs in nutritional value, flavor and most functional properties.”