From your friends at the Incredible Edible Egg
When you use just egg whites in a recipe, don’t let the yolks go to waste. Extra yolks can be kept in the refrigerator for up to two days, covered with water and stored in a tightly covered container. Or whisk them with a pinch of salt or sugar and freeze for up to three months.
Substitute 1 cup cholesterol-free egg product for the whole egg and 3 egg whites.