THE SCIENCE OF ICE: Ice is the frozen form of liquid water. The same substance will behave differently at various temperatures and pressures. Water (H2O) is the most familiar example. It can be a solid (ice), a liquid (water), or a gas (steam), but it is still made up of molecules of H2O, so its chemical composition remains unchanged. At sea level, water freezes at 32 degrees Fahrenheit (0 degrees Celsius) and boils at 212 degrees Fahrenheit (100 degrees Celsius), but this behavior changes at different altitudes because the atmospheric pressure changes. In fact, get the pressure low enough and water will boil at room temperature. The critical temperature/pressure point at which H2O changes from one form to another is called a phase transition.
WHAT IS GELATIN? Gelatin is a processed protein called collagen, derived from the bones, hooves and connective tissues of cows or pigs. Those parts are ground up and mixed with acid or other chemicals to break down the cellular structure, thereby releasing the collagen. Boiling it causes a layer of gelatin to form on the top, which can be skimmed off for further processing. Eventually it ends up in your local grocery store aisle in powder form, or in this case, in ice cream.
The Materials Research Society contributed to this report. This report has also been produced thanks to a generous grant from the Camille and Henry Dreyfus Foundation, Inc.