Doesn’t corn syrup or glucose help to prevent crystallization in marshmallow? Indeed so, reader Lauren. Those individual sugars work almost like little ball bearings, getting in between the sucrose molecules and preventing them from stacking up on each other like LEGOs and forming crystals. The things is, in a Peep a little crystallization isn’t such a bad thing. They start forming quite quickly in fact, giving peeps a crunchy exterior in as little as 12 hours. A lot of people love peeps that way…Mrs. Pastry especially.