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.
If you don't find a sell-by date on the carton, use the eggs within three weeks of the carton packing date. Within that window of time, your eggs will be at their highest quality, meaning the yolk will be high and upstanding, and the white will be tall and firm when you whip them. According to Foodsafety.gov, raw eggs in the shell can be kept in the refrigerator for three to five weeks.