Foods, like all things organic, do not last forever. They decay, rot, and are consumed by microorganisms. They undergo changes in composition, flavor, and nutritional value. The time it takes for such changes to occur depends upon the nature of the food. Some foods have built in defense mechanisms and natural preservatives that help to delay spoilage. Others spoil rather quickly and must be preserved in some manner if they are to be stored for later consumption.

Over time, people have developed numerous methods of preserving food. They range from the ancient idea of storing foods in containers to the modern technology of aseptic processing and packaging.

Natural enzymes present in all foods of animal or vegetable origin catalyze chemical reactions which cause changes in the food. These reactions will eventually lead to decomposition of the food, unless something is done to inactivate the enzymes. More specifically, such reactions result in the breakdown and softening of flesh. This then opens the door to microbial action. Enzymes are responsible for the browning and softening of fruit and vegetables. They also cause changes in the texture and flavor of meats, poultry, and seafood.

Microorganisms are a major cause of food spoilage. Yeasts, molds, and bacteria need food just as we do, and seize every opportunity to get the proteins, sugars, and minerals they require for survival. Microorganisms can be introduced to foods indirectly through the actions of insects, pests, and humans. They are also naturally present in the environment and are a normal part of the flora of many food crops. For example, many yeasts and molds are commonly found on the surface of apples. These microorganisms are native to the orchards where apples are grown. Unless something is done to stop them, they will eventually cause apples to rot. They are aided in their breakdown of the apple by the apple's own enzymes.

Some foods contain natural defense mechanisms which help to slow microbial related decay. The outer skin of an apple, when unbroken, acts as a barrier against microbial entry. However, they can gain entry with even the slightest break in the skin. Another natural defense mechanism is acidity, such as in certain fruits. In addition, some foods contain chemicals that, while harmless to humans, act to inhibit microbial activity.

The specific environmental conditions to which a particular food is exposed can also lead to spoilage. Oxygen from the air can act on unsaturated fats in meats and seafood, causing rancidity, off flavors, and odors. Light can also lead to chemical reactions which cause undesirable changes in foods. Humidity from the air and moisture from any source can increase a food's susceptibility to microbial decay. Temperature is another important environmental factor. To a certain degree, warmer temperatures lead to increased rates of both enzymic and microbial breakdown.

Thus, if foods are to be stored for later consumption, typically some means of preservation is necessary. People recognized this fact early on. They learned through observation that certain foods kept longer than others. This knowledge provided the first clues on how to preserve food for future use. Although they didn't know why, they learned that keeping food away from moisture, light, and air helped to preserve it. Thus, they developed ways to keep food away from these elements. They soon learned that cooking, smoking, drying, and salting foods aided in preservation. Fermentation, besides changing the characteristics and improving the flavor of many foods, was found to be a good method of preserving them.

Continued In: Fight Spoilage & Keep Foods Fresh Longer! Part 2