No not all food products exhibit its actual contents. You are right that most of the products like peanut butter and other instant foods contain preservatives and chemicals to make them available throughout a year and also to make them taste better.
Some products do display some bizarre chemical name as preservatives, but the consumers have no idea about its implications on their health. Additionally, there has also been ethical problems over how these preservatives and taste adders are derived.
For instance, some of us are still unaware that red food color is produced by crushing a bug called cochineal. The byproduct of this insect is used in food processing industry and cosmetics industry, but we never see the name of cochineal or the name of any bugs in the ingredient list.
Probably, the food labels display alternative chemical names for weird derivatives and do not mention that it contains animal derivatives or the exact source from which it is derived. Imagine how many people would buy food color if they knew its true origin.
The same happens with flavoring agents where food labels just mention artificial identical flavors. That means the flavors are not derived from where it is supposed to be.
For instance, if a vanilla flavored cake mix contains ingredients as artificially identical flavors, then it means the flavor is not natural vanilla extract but artificially derived from an identical flavoring agent.
For more details,check out webecoist.com for weird and gross ingredients in packaged foods.
