It's all due to food additives. A food additive is any substance that is used for a specific purpose in the production, processing, treatment, packaging, transportation or storage of food. Some foods are enriched with nutrients that are lost in processing. Other foods are fortified, meaning nutrients not present before processing are added. For example, vitamin A and D in milk, folic acid in some grain products, and calcium in orange juice.
Bacterial contamination can cause foodborne illness, such as botulism and salmonella poisoning.
Food and color additives are more strictly regulated today than at any other time in history. The Food and Drug Administration has authority over food and food ingredients and defines requirements for truthful labeling of ingredients. There are two groups of substances that are exempt from the food additive regulation process. One is the preservative used in luncheon meats, such as sodium nitrite or potassium nitrite. These include salt, sugar, spices, vitamins and monosodium glutamate, along with several hundred other substances.