From Smoked Mastodon to Salt Pork

Questions about the value and safety of different categories of food are especially difficult to answer because people have been modi­fying foods almost since the dawn of civilization. In fact, without certain types of food modification, the human species might never have survived on Earth.

By far the most common and oldest type of food modification used by humans is food preservation. Imagine, for instance, a com­munity of early humans in northern Europe trying to survive a long, cold winter with no method for preserving food. Or picture a group of hunters in tropical Africa who have just killed a huge animal that could provide them with meals for weeks. In both cases, men and women faced the problem of preserving food that has become avail­able at one time for use at a later time—often, much later.

Over the millennia, people have discovered a variety of meth­ods for keeping food from "going bad"—in other words, decaying. Cooking, smoking, freezing, and drying were among the earliest food preservation techniques. The use of a broad range of spices, the most important of which was salt, also proved effective as a way of preserving foods.

Although early humans developed a variety of methods for preserving food, it is doubtful that they knew anything about the mechanisms by which such techniques preserved foods; they simply knew that they worked. Deeper understanding did not come about until the 19th century, when researchers such as the French chem­ist Louis Pasteur (1822-95) and the German bacteriologist Robert Koch (1843-1910) discovered the role of microorganisms in the de­cay of organic material and the spread of disease. These scientists were able to show that certain environmental conditions favored the growth of bacteria (heat and moisture), while others discouraged their survival (cool temperatures and a dry environment).

This information helped explain the success of various food pres­ervation techniques. For example, drying preserves foods because it removes much of the moisture that bacteria need to grow. Freezing works because it lowers the temperature of food to the point that the growth of bacteria is severely inhibited. Spices are effective for a variety of reasons, one being that they may release chemical compounds that are toxic to bacteria; cloves, for example, release a compound called eugenol that slows the growth of bacteria. And smoking food preserves it because smoke, like spices, contains a number of chemicals that inhibit the growth of bacteria. One of the most widely used of modern synthetic preservatives, butylated hy-droxyanisole (BHA), is a natural component of smoke.