By Harold McGee
The paragraphs directly above describe various bonds as “weak” and “strong,” easily or not so easily formed and broken. The idea of bond strength is useful because most cooking is a matter of the systematic breaking of certain chemical bonds and the formation of others. The key to the behavior of chemical bonds is energy. The word is a Greek compound of “in” and “force” or “activity,” and now has as its standard definition “the capacity for doing work,” or “the exertion of a force across a distance.” Most simply, energy is that property of physical systems that makes possible change. A system with little energy is largely unchanging. Conversely, the more energy available to an object, the more likely that object is to be changed, or to change its surroundings. Our kitchens are organized around this principle. Stoves and ovens change the qualities of food by pouring heat energy into it, while the refrigerator preserves food by removing heat and thus slowing down the chemical changes that constitute spoilage.