Heating Foods

Heat is the energy that is produced by the rapid movement of molecules. The molecules in living organisms always have some motions, while cold temperatures slow it down. Freezing and boiling are extremes of the range in temperatures encountered in food preparation that owe their effects to changes in this kinetic energy of molecules.The three main scales used to measure heat intensity are Fahrenheit, Celsius or Centigrade, and Kelvin (^oK). The last is used primarily in scientific research, so we will not touch on it here.

The freezing point of water is 32^o on the Fahrenheit scale and 0^o on the Celsius scale. Its boiling point at normal atmospheric pressure is 212^o on the Fahrenheit scale and 100^o on the Celsius scale. The boiling point changes slightly with altitude; 1^oF (2.2^oC) must be subtracted for every 500 feet increase in elevation. Other compounds in the water, such as sugar or salt, influence its boiling and freezing temperatures, so all three scales pertain to pure water. Other materials have their own freezing and boiling points.