Food preservation is a method of slowing down spoilage and extending the shelf life of food. This has been used way back a few centuries ago by the earlier inhabitants. There a number of ways to preserve food. Some of these are in ancient ways, and still being used until today. Some of the most common preservation techniques are freezing and refrigeration, canning, salting, pickling, drying, and sugaring.
Freezing and refrigeration is commonly used these days by the help of a refrigerator and/or freezer, a staple in everyone's kitchen. Root cellars and cold cellars were historically used before to keep food, and are still used in some parts of the world, especially in the colder regions.
Canning includes cooking of food and storing it in sterile jars or cans, then boiling containers to kill any remaining bacteria. This method is sometimes combined with pickling. Jams, jellies and preserves are some example. Salting or also called curing, uses the osmosis process that draws moisture from the meat. Meat is cured with salt or sugar, and sometimes a combination of both.
Pickling on the other hand is the process of using an edible anti-microbial liquid. Commonly-used pickling agents are vinegar, alcohol, vegetable oil, olive oil or brine. It is sometimes categorized as chemical pickling, which usually involves boiling or heating until the food becomes saturated. We have cucumbers, corned beef, eggs and fish as familiar examples. Considered one of the oldest methods is drying. In this process, enough water activity is removed in the food to put off bacterial growth which hinders decay.
Sun drying and smoking are common techniques, taking beef jerky and raisins as common examples. Similar to pickling, sugar is used to preserve fruits. Peaches, pears, apples and apricots are preserved by drying it out first then packing it in sugar. Raw sugar can be used or a high-content liquid, such as honey or molasses.
Take a look around you. Just imagine how life would be like if preserving food was not at all discovered. You would not even be aware of many of the favorite foods you eat today.