Restaurants and food manufacturers have pasteurized liquid egg products (refrigerated and frozen) available to them from straight yolk to whole egg, to straight whites and many specialty blends in between. The eggs are separated, and the yolks and whites are pasteurized separately. They are then blended in a wide variety of ratios for specific cooking and baking purposes. Great products.
Most grocery stores carry all white liquid egg products (most have color added to make them look like whole eggs when scrambled), and many carry liquid whole egg equivelents (Better'n Eggs) 1/4 cup = 1 shell egg. http://www.michaelfoods.com/foodservice/products-eggs.cfmhttp://www.michaelfoods.com/food-ingredients/pdf/Food-Ingredients-Product-List-082709.pdf