Processed food is simply a food that has been altered from it's natural state. Sometimes for convenience and sometimes for safety. The methods used include; canning, freezing, refrigeration, dehydration and aseptic processing.

Not all processed foods are bad, milk, for an example, would be considered processed because it is pasteurized to kill bacteria and homogenized to keep fats from separating. Raw milk would be a lot better for us but laws prohibit us from attaining it and consuming it.

Another healthy example of food processing is frozen vegetables. While fresh may be best, freezing vegetables preserves vitamins and minerals and makes them convenient to cook and eat all year around.

Fruit and vegetable juice is also an example of a healthy processed food. In fact, some orange juice is fortified with calcium to make it even more nutritious.

Of course, there are a lot of processed foods that are not good for us. Many processed foods are made with trans fats, saturated fats, and large amounts of sodium and sugar. These types of foods should be avoided.

Some of the big players in Processed foods include:

Canned foods high in sodium and additives,white breads and pastas made with white-refined or enriched flour, packaged snack foods; chips and goldfish crackers, high-fat convenience foods; cans of ravioli or spaghetti, frozen dinners, packaged cakes and cookies, boxed meal mixes and side dishes, boxed cereals high in sugar and additives and meats processed with Nitrates and Nitrites.

This information was gleaned from an article featured on About.com