In the U.S. the Memorial Day weekend marks the unofficial start of summer—and the beginning of barbeque season. As you sear the meat and toast the buns, have you ever wondered why grilling beats boiling? Or why ketchup and mustard tend to separate, but mayonnaise does not? Or why a pickle lasts so long? 

Our friends at NBC Learn are producing an ongoing set of videos explaining the basic chemistry behind everyday items as part of its Chemistry Now effort. (Check out the chemistry of chocolate.) The videos include a series on the hamburger and its symbiotic accompaniments—all part of the celebration of the International Year of Chemistry 2011.

The Chemistry of Burgers

Americans down 14 billion burgers a year. See how Maillard reactions create that nicely darkened, crispy and tasty outside. Vegetarians: skip to the next video.

The Chemistry of Bread

The yeasty science behind the bun also applies to doughnuts, if that's how you like to eat your burgers.


The Chemistry of Tomatoes

How ethylene tells tomatoes to convert starches to fructose and make lycopene, a powerful antioxidant that has a relation to werewolves.


The Chemistry of Pickles

You don't see it, but a battle of bacteria rages on in cucumbers. How a briny solution tips the scales to one particular species and keeps the fruit edible for a long, long time.


 The Chemistry of Condiments: Ketchup, Mustard and Mayo

Two of these items are suspensions, and other is a colloidal dispersion. What's the difference? After a time, you have to stir one of them.