An emulsion, as defined by Food Technology, is a “temporarily stable mixture of immiscible fluids, such as oil and water, achieved by finely dividing one phase into very small droplets.”1 Nature designed multiple functions into the egg, including its ability to emulsify. While most commonly associated with mayonnaise,2the emulsifying capacity of whole eggs, egg yolks and even egg whites plays a role in baking and other applications. The absence of eggs in certain formulations such as mayonnaise can affect emulsion stability and final product appearance.2
Fresh liquid eggs, frozen eggs and spray-dried all have the capacity to emulsify, and according to Christine Alvarado, Ph.D., Texas A&M University, there is no essential difference found between them.3 The most popular forms however, include liquid, refrigerated whole eggs or frozen yolks. Frozen yolk has 10 percent added salt or sugar to promote a smooth, creamy, viscous yolk. Egg white emulsifies due to its albumin protein component, while for egg yolk it is its lecithoprotein content.4
Specifically the egg as emulsifier:
- Acts as a stabilizing agent by reducing surface tension
- Reduces the force required to create the droplets that comprise an emulsion
The reduction of surface tension is due to the lecithin or phosphatidylcholine contained within the egg yolk. This amphiphilic molecule has two ends, one hydrophobic and one hydrophilic, which minimizes the energy required to form an emulsion by reducing oil/water interfacial tension.5
There are multiple factors that can affect an emulsion’s stability such as temperature, mixing speed and time and more. Two critical pieces of the puzzle include viscosity and the size and uniformity of the droplet.
An emulsion is thicker or more viscous than its separate components, or the oil and water it contains. Egg yolks provide a viscous, continuous phase. This promotes stability in emulsions because it prevents the dispersed oil droplets from moving around and gathering, or coalescing. Adding egg yolk to whole eggs increases emulsion viscosity, lending it greater stability.
In addition, the smaller the droplet and more uniform in size, the better the emulsion and the better the mouthfeel and texture of the finished product. When mixed at the proper speed and adding ingredients in the proper order, formulators can control droplet size and dispersion. For example, oil must be added slowly to water so that the lecithin within the egg yolk can thoroughly coat the small droplets. This coating acts as a barrier to prevent the droplets from joining back together (flocculating or coalescing) to enhance emulsion stability and improve product appearance and texture.6
Some common applications for eggs as emulsifier beyond mayonnaise and sauces includes salad dressing, ice cream and baked goods such as muffins, bread, cinnamon rolls and cheesecake6 to name a few.
In ice cream, eggs added during the freezing process help promote a smoother texture and ensure the ice cream does not melt rapidly after serving. Emulsifiers also help improve freeze/thaw stability, an important quality for ice cream as well as sorbets, milkshakes, frozen mousse and frozen yogurt.7
Within the commercial baking industry, which relied upon eggs as the first emulsifier, a proper emulsion impacts both product and process. Eggs can help increase product volume, supply a tender crust and crumb, finer and more uniform cell structure, a bright crumb color and slow the crumb from firming, increasing product shelf life. In terms of process, emulsification activity enables proper blending of ingredients and protects the dough during mechanical handling.4
- Clark J. (2013). Emulsions: When Oil and Water Do Mix, Food Technology magazine, Volume 67, No. 8
- Munday E, Werblin L and Deno K. (2017). Mayonnaise Application Research: Comparing the Functionality of Eggs to Egg Replacers in Mayonnaise Formulations, CuliNex, LLC, Seattle, USA
- Alvarado C. (2016). Emulsification [PowerPoint presentation] College Station, TX
- Pyler EJ and Gorton LA. (2010). Baking Science & Technology, Fourth Edition, Volume 1, Sosland Publishing Co., Kansas City, Missouri, USA
- McKee S. (2016). Eggs as a Functional Emulsifier [PowerPoint presentation]. Auburn AL
- Munday E, Werblin L and Deno K. (2017). Cheesecake Application Research: Comparing the Functionality of Eggs to Egg Replacers in Cheesecake Formulations, CuliNex, LLC, Seattle, USA
- Stadelmen WJ and Cotterill OJ. (1995). Egg Science and Technology, Fourth Edition, Haworth Press, Inc., New York, USA
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Eggs and egg whites can be whipped into a foam for aeration and to improve product texture and appearance. Egg products’ whippability plays a role in baking and frozen desserts such as ice cream, in addition to certain confections. The various types of egg products display varying levels of whippability, with differences between egg white, whole egg and egg yolk. Dried eggs also perform in a different manner than liquid or frozen in terms of whippability.1
Pasteurization, a process applied to all further processed egg products, does not impact whippability.2 Egg white for example is very stable in a dried state and its whipping properties remain unaffected unless excessively high temperatures are applied. However the whipping properties of egg products containing yolk do witness a loss in efficacy when in dried form, so refrigerated and frozen are recommended for certain applications.
In angel food cake, egg whites comprise the sole egg ingredient. Dried egg white solids if chosen for application often are reconstituted prior to use. Proper mixing procedures help maximize foam volume. In commercial practice, egg white solids perform well with continuous batter mixing systems.3 When whipped, the proteins within the egg white unfold or denature to form a relatively stable foam structure useful in angel food cake, as well as sponge cake, certain confections and other baking applications.
Whippability has a bit of a different meaning when it comes to ice cream. Whippability refers to the whipping quality of the ice cream mixture itself. The proper emulsifier, such as egg yolk, results in reduced air cell sizes and a homogeneous distribution of air in the ice cream. The lecithin-protein complex in egg yolk solids improves the whippability of ice cream, also lending it a more dry appearance, smoother body and texture and a slower meltdown.4 One reference indicates eggs have a pronounced effect in improving the body and texture, have almost no effect on the freezing point and increase the viscosity—all positive benefits in terms of ice cream manufacture.5
There are mix calculations that help formulate ice cream and frozen dairy desserts, to determine the percentage required of the various ingredients.6 Egg yolk solids are especially desirable in mixes in which butter or buttermilk is used as a main source of fat. Egg yolks or whole eggs improve the rate of whipping more if they are sweetened with 10 percent sugar or corn syrup before they are frozen or dried.
Ice cream, according to the U.S. Code of Federal Regulations (CFR) can be called custard or “French” if the egg yolk content is at least 1.4%.7
1. Stadelmen WJ and Cotterill OJ. (1995). Egg Science and Technology, Fourth Edition, Haworth Press, Inc., New York, USA
2. Belitz H, Grosch W, Shieberle P. (2009). Food Chemistry, 4th revised and extended Edition, Springer Berling Heidelberg
3. Pyler EJ and Gorton LA. (2010). Baking Science & Technology, Fourth Edition, Volume 1, Sosland Publishing Co., Kansas City, Missouri, USA
4. Campbell J, Marshall R. (2016). Dairy Production and Processing: The Science of Milk and Milk Products, Waveland Press, Inc., Long Grove, Illinois, USA
5. Marshall R and Arbuckle WS, (2000) Ice Cream, Fourth Edition, Aspen Publishers, Inc., Gaithersburg, Maryland, USA
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5th Generation Egg Farmer
Midwest Poultry Services, Mentone, IN
Midwest Poultry Services is an egg farming tradition in Indiana. The fifth-generation operation has been family-owned and operated since 1875 and now houses more than two million hens. The Krouse family is committed to the community, providing sustainable jobs and an outlet for local farmers with 20,000 acres of corn.
Bob’s family business started in North Manchester, Indiana, in 1875 with a water powered grain mill on the Eel River. Today, the family still has a feed mill on that same farm, and Bob’s son Dan recently came to work in the family business as part of the sixth generation.
Today, Midwest Poultry Services is the 8th largest egg producer in this country with 300 employees and 8.5 million hens spread across farms in Indiana, Illinois and Ohio. And the farm still produces all of its own feed — more than 500 million pounds per year, buying 40,000 acres of corn from local farmers and soybean meal from 45,000 acres.
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3rd Generation Egg Farmer
Hickman’s Family Farms, Buckeye, AZ
Hickman’s Family Farms is Arizona’s largest – and only – egg producer. The third-generation operation that began on Grandma Hickman’s backyard porch has been family-owned and operated in Arizona since 1944 and now houses more than four million hens.
In addition to their commitment to providing fresh eggs for a good price, Hickman’s Family Farms utilizes stringent methods of conservation and recycling to remain as environmentally-friendly as possible. Always a “good egg” and supporter of the community, Clint and the Hickman family contribute to a variety of charitable efforts and causes year-round in Arizona.
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2nd Generation Egg Farmer
Esbenshade Farms, Mount Joy, PA
Esbenshade Farms started in 1963, but the family’s farming history dates back seven generations. Alongside employees who share its commitment to excellence and integrity, the Esbenshade family cares for its hens, monitoring their comfort, health and safety. Chris Esbenshade, the second generation to lead the egg farm, is proud to produce high-quality eggs for his family and yours.
His parents, Glenn and Rachael Esbenshade, started with a small flock of hens in 1963 that has grown to include more than 2 million hens today. Chris is honored to produce an all-natural, nutritious, safe and affordable food that continues his family’s history in agriculture, which has been their way of life since the early 1800s.
Their hens’ comfort, health and safety are the top priority at Esbenshade Farms, where a state-of-the-art farm allows hens to live comfortably in a safe, climate-controlled environment while reducing their carbon footprint.
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Yield: 12 servings; 2 (12-inch) pies
Yield: 6 servings