McDonald's uses 3 different eggs. Only 1 of them is cracked in the restaurant. The Egg McMuffin gets a Grade A egg cracked into a ring on the grill. The Big Breakfast scramble is poured from a carton of eggs and citric acid. The folded egg on the biscuits and McGriddles is eggs, nonfat milk, modified food starch, salt and citric acid. A supplier cooks it, folds it and flash freezes it. The store warms it on the grill. Citric acid keeps a cooked egg from going gray on a hot hold, and the starch holds water in a patty that's been frozen and thawed so it doesn't weep on the biscuit. The milk adds volume and softens the bite. McDonald’s purchases over 2 billion eggs in the US and Canada a year.