Meat, fish, fruits, and vegetables are highly perishable because they spoil easily. Once food is spoiled, it is no longer fit for consumption since it may cause loose bowel movement or LBM or may trigger other stomach reactions. Foods spoil because of molds and bacteria; they eat the food and they live in it.

To preserve food, molds and bacteria should be killed. Their growth should be stopped and there are 5 common ways to do that:

Food placed in the refrigerator doesn't spoil for some time. That's why people who have refrigerators could buy a whole week supply of food. Meat, fish, vegetables, and fruits can be kept in the freezer for a long period of time without spoiling them. In the market you will notice some fish are stored inside the containers with ice in it to keep them fresh.

Refrigeration and freezing are probably the most popular forms of food preservation today. In refrigeration, the bacterial action on the food is slowed down; it takes a week or two to spoil. In freezing, bacterial action on the food is stopped. Bacteria are completely inactive if frozen.

Almost all foods - meat, vegetables, fruits beverages and other foods can be preserved in refrigerator and freezer. Taste and texture of foods has no effect in refrigeration while in freezing, it has minimal effects on vegetables and fuits, and no effect on the taste of meat. Due to the minimal effects of refrigeration in foods, it has been accounted as popular form of preservation.

Drying preserves some foods. Dried fish and meat are preserved foods. Legumes are preserved by drying, too. Mongoes, garbanzos, beans, are examples of dried seeds. They can be kept for a long time. Raisins are dried grapes.

Dehydration. To preserve some foods you have to dehydrate them. Dried fruits, potatoes in a box, dried vegetables, powdered milk, pasta, powdered soups, powdered sauces, and powdered meat you see in the grocery store are dehydrated products.

When foods are dried, bacteria will become inactive. So, foods in air-tight containers will last for a long time.

Freeze-drying is a special form of drying. All moisture are removed and food taste won't be affected than normal dehydration.

In freeze-drying, food is frozen and placed in a strong vacuum. This is used when making instant coffee. This also works well on fruits like apples.

Substances that are used for preserving foods are called preservatives. Sugar, salt, spices, saltpeter, and vinegar are examples of preservatives. Smoke also preserves some foods. Ham and bacon are cured by smoking. Candied fruits are preserved by sugar.

Salting, especially of meat, is an ancient preservation technique. The meat covered by salt does not spoil because bacteria cannot thrive in salty environment. Moisture in food is also drawn out by salt. When meat is salted in cold weather, it will last for years.

Pickling. In the past, this was widely used to preserve meat, fruits and vegetables. Today, it is used to make pickles such as pickled cucumbers. Preservative qualities of vinegar and salt are combined to produce pickles. Salt and vinegar inhibits the growth of bacteria. 

How to make pickled cucumbers? Soak cucumbers in 10% saltwater brine for several days. Then, rinsed and stored in vinegar to preserve them. It's that simple!

Using heat to kill bacteria is a good way to preserve food. This is called sterilization. Canned foods and preserved foods in jars have been sterilized.

Foods kept where air cannot reach them is preserving by excluding air. Canned foods kept air out of the food. Canning is one of the most common ways of preserving food. Many foods can be canned. Sometimes it’s cheaper to buy canned foods than to can them at home. Preserving food at home is expensive if you need to buy the food to be preserved. The materials and equipment for preserving, like wide-mouthed glass jars, rubber, and pressure cooker, are costly. However, when there is good harvest, canning should be done so the food would not be wasted. Canned products should be kept in a cool, dry place. The jars of fruits, vegetables, and other preserves should be labeled properly. Shelves should be kept clean and arranged well so cans and jars could be seen easily.

Canning. This has been around for many years since 1825. People can store foods in can for a very long time. The food in the can must be boiled to kill the bacteria and the can must be sealed - can be either before or while the food is boiling. The food in the can does not spoil because it is completely sterile. Once you open the can, you have to refrigerate its contents because bacteria will begin destroying the food.

Generally, cans are considered as being metal, but any sealable container - glass jar, plastic pouch or foil - can serve as a can. For example: milk in a box on the shelf is considered as "canned milk." Canned milk is made sterile by using ultra high temperature pasteurization, so even at room temperature it does not spoil.

Refrigeration and freezing is preferred to canning. Why? Because in canning you have to boil the food which can alter its taste and texture, and its nutritional content.