Sodium stearoyl lactylate (SSL) forms strong bonds with the flour proteins during gluten development, improving dough strength. During protein denaturation at baking temperatures, these bonds weaken and SSL is able to translocate to the starch molecules, reducing their staling rates during storage 1.
Place the ice cube tray in the freezer and freeze the egg whites until firm. Pop the egg whites out and transfer them to a zip-top freezer bag and return to the freezer. Now, whenever you need one, two or three egg whites for an egg-white-only recipe, you have them, premeasured, at your disposal.
Egg whites freeze very well and it is a useful way to keep leftover fresh egg whites. Freeze the egg whites individually for ease, you can freeze them in ice cube trays and then transfer to a resealable bag when solid.