Definition of processed foods

When should you consider foods to be "processed"? One suggestion I've heard is that processed foods are those whose character has changed from the original. However, I think that's misleading.

Some foods can undergo a change of character, and yet still be perfectly healthy. The creation of butter by whipping cream for an extended time is one example. Even most cooking processes will change the character of the original foods in some way.

One type of food processing that’s not healthy is when it’s natural shelf life is over-extended through mechanical or chemical treatment. One way that’s done is by removing some of the key nutrients that potential pests like to eat. For example, potassium can be replaced with sodium (salt); unfortunately, many micronutrients are removed at the same time. The final result is that while the caloric content of the food may remain, much of the nutritional content does not.

Another type of food processing is when food is combined with non-foods. For example, chemicals galore, for purposes that range from changing the food’s texture or color to changing its taste or enhancing shelf-life.

How about this definition: I consider foods to be “processed” when they either have essential nutrients removed from them, or when they are combined with non-foods.