The egg yolk and white contribute very different characteristics to baked goods, and understanding how they work is key to finding potential replacers.
“The egg white is the main component in strengthening, as it contains a majority of the protein in the egg,” said David Guilfoyle, group manager of bakery fats and oils for DuPont Nutrition & Health.
Albumin is the egg white’s primary protein source, and upon heating, the albumin structure denatures to create a special gel strength that most other proteins do not have. This strength is important, especially in cakes, as the batter is heated, the volume increases, and the aerated albumin gel structure begins to denature and the leavened structure is set.
“Potato isolate protein and milk whey without lactose are two ingredients that have nearly similar gel strength to egg,” Mr. Guilfoyle said. “Other proteins set too quickly, creating a dense structure, or begin to collapse due to the weight of the ingredients in the formulation before the structure can be set.”
Egg whites are also the powerhouse behind aeration, or creating foams. As the egg white is whipped, air gets trapped within the albumin, which stretches out with protein-coated air cells that become stable enough to hold the heavy ingredients.
“As the foam is heated, the protein-coated air cells expand and the structure lifts, and upon reaching a certain temperature, the foam structure sets and holds the bound ingredients in place,” Mr. Guilfoyle said. “We offer various hydrocolloids that can aerate similarly to egg whites.”
The egg yolk contains the emulsifier component lecithin, which allows water and oil to become miscible, creating either an oil-in-water or water-in-oil emulsification. If this is the function that needs replacing, it is possible to source lecithin from plants such as soybean or sunflower.
“They are all equally as functional as the lecithin from egg,” Mr. Guilfoyle said.
Natural Products, Inc. manufactures soy-based egg and milk replacement systems, which tend to be hydrophilic, even more so than eggs. Jon Stratford, sales and marketing manager for Natural Products, said the company’s egg replacers are formulated to replace whole egg powder at a 1:1 ratio.
“However, because the soy tends to bind so much water, it is not uncommon for our customers to find they need to reduce our product slightly, versus the quantity of eggs that were being used, to avoid having to add more water to their formulation,” Mr. Stratford said. “On the other hand, in some cases, it might be an advantage to add a bit more water, as that can improve the shelf life of fresh-baked products.”
The water-binding attribute dictates the most suitable applications.
“Our egg replacers also provide emulsification,” Mr. Stratford said. “Applications where eggs mainly provide emulsification tend to work best with our egg replacers.”