Eggs as a Functional Emulsifier Shelly McKee, Auburn University American Egg Board

Egg Industry Structure Producers Shell Egg Grading Further Processors Food Manufacturers Bakery Supply Food Brokers End Users 1.2 4

Egg Products Processing Overview HOLDING Refrigerated no longer than 7 to 10 days BREAKING and separating yolks, whites, shells – Filtered – Mixed – Chilled PASTEURIZATION PACKAGING REFRIGERATED LIQUID EGG PRODUCTS FROZEN EGG PRODUCTS The design and construction of EGG PROCESSING EQUIPMENT meets E-3-A or 3-A Sanitary Standards DRIED EGG PRODUCTS 1.3 5

Nature’s Most Perfect Food – The Egg! Egg Structure Shell Air Cell Shell Membranes Yolk Chalazae Latebra Chalaziferous Layer Germinal Disc Thin Albumen (White) Vitelline (Yolk) Membrane Thick Albumen (White) Chalazae Nature’s Most Perfect Food – The Egg! 1.5 6

Egg Yolk Composition Approximately 50% water, 17% protein (mainly ovovitellin), 33% lipids (mainly triglycerides, lecithin [phospholipids] and cholesterol) Minerals: iron, phosphorus, calcium, manganese, iodine, copper and zinc Vitamins A and D, B12, E, biotin, choline, folic acid, inositol, pantothenic acid, pyridoxine and thiamin Xanthophyll: main yellow pigment Egg Yolk Composition 33% 50% 17% 2.4 12

Egg Yolk Composition Triglycerides (Neutral Fats) 65.5% 50% 27% 11% 6% Oleic Palmitic Linoleic Stearic Other 65.5% 50% 6% 27% 11% 28.3% Phospholipids Lecithin (phosphatidylcholine) 73% Cephalin (phosphatidylethanolamine) 15% lysophosphatidlycholine 5.8% sphingomyelin 2.5% lysophosphatidylethanolamine 2.1% plasmalogen 0.9% inositol phospholipid 0.6%

Emulsification The phospholipids, lipoproteins and proteins found in egg yolks are surface active agents that enable the formation of emulsions from immiscible liquids such as oil and water. Egg yolks can be used to fortify whole egg blends to increase emulsifying action No essential differences are found in emulsifying properties of dried whole egg and yolk and fresh liquid eggs 4.6 40

Emulsions/Surface activity- a stable mixture of two immiscible liquid phases, one which is dispersed in the other Mayonnaise

Emulsification Applications Mechanisms Mayonnaise Hollandaise sauce Salad dressings Baked goods Mechanisms Egg emulsifying properties come from the yolk

Emulsifiers in the egg yolk Phospholipids-lecithin Lipoproteins Proteins- having hydrophilic and hydrophobic regions

Emulsions/Surface activity 3 Components necessary for an oil-in-water emulsion a) oil b) water c) interface, proteins, phospholipids, lipoproteins Water Oil Proteins, phospholipids, lipoproteins

Good Stable Emulsion Should be viscous to hold suspended ingredients in place Droplets dispersed (oil or water) should be small enough to remain in suspension and should be evenly distributed throughout the matrix

Emulsions Factors affecting emulsions Viscosity (Stability over time) Amount of emulsifier (Formation and Stability) ratio of emulsifier/fat/water Additives 0.05% sodium-2-lactylate increases emulsion stability

Mayonnaise is made by combining lemon juice or vinegar with egg yolks. Eggs (containing the emulsifier lecithin) bind the ingredients together and prevent separation. Adding oil too quickly (or insufficient, rapid whisking) will keep the two liquids from combining (emulsifying). As the sauce begins to thicken, oil can be added more rapidly. Seasonings are whisked in after all of the oil has been added.

Long shelf life (1 year), functionality, variety blends

FROZEN EGG PRODUCTS Frozen yolk has 10 % salt or sugar added to prevent irreversible protein gelation. Result is a smooth creamy, viscous yolk.

Egg Products Sanovo Foods produces enzyme-modified product Heat-stable egg yolk. Uses enzymes to degrade phospholipids phospholipids which account for 7-8% of the egg yolk. The enzyme converts a large part of the lecithin in the egg yolk into lysolecithin, which has much better emulsifying properties.

Mayonnaise Cheese Cake Cinnamon rolls Made with liquid frozen whole egg Made with liquid frozen salted egg yolk Cheese Cake Cinnamon rolls Made with liquid frozen sugared egg yolk

Some common applications of emulsifiers Bread It is possible to make bread without emulsifiers but the result is often dry, low in volume and easily stales. As little as 0.5% emulsifier added to the dough is enough to achieve an enhanced volume, a softer crumb structure and a longer shelf-life. Chocolate All chocolate products contain 0.5% of lecithin. These emulsifiers are added to provide the right consistency of the chocolate, so it can be molded into plates of chocolate, chocolate bars etc.

Some common applications of emulsifiers Ice-cream Ice-cream: both a foam and an emulsion it contains ice crystals and an unfrozen aqueous mix. Emulsifiers are added during the freezing process, to promote a smoother texture and ensure the ice-cream does not melt rapidly after serving. They also improve freeze-thaw stability. All this applies to other desserts such as sorbet, milkshake, frozen mousse and frozen yogurt as well.