In the true spirit of Valentine’s Day, I ate a lot of chocolate (and chocolate chip cookies) today. Cocoa is made from cocoa butter, a lipid, which we briefly touched upon. Making chocolate is a lengthy and complex process. In one of the final steps, tempering, the cocoa buyer is left to freely crystallize into crystals of different sizes. This reminds me of what we did in the second lab when we made salt solutions and looked at some crystals under the microscope. Interestingly, many cocoa crystals are too small for the naked eye. It is these crystals that cause chocolate to have a shiny layer and break sharply. In a solid piece of chocolate, the cocoa butter fats are in a rigid crystalline structure. When heat is added, the rigid structure becomes more fluid as the interactions break. Clearly, biochemistry is responsible for the delicious properties of chocolate, something I don’t usually think about when I’m enjoying it.