We know that food consists of proteins, fat, carbohydrates and vitamins
To a lower level, that boils down to carbon, hydrogen, oxygen, nitrogen, sulfur, calcium, potassium, phosphorus and other elements.
Can we fabricate any type of food from various types of junk (metal, plastic and paper) and even from dirt?
If you take a bar of iron, you will get just iron and maybe some oxygen if it was a tad rusted. In general with metals alone you will miss most of the elements I listed above.
If you take only plastic, you will get carbon, hydrogen and maybe nitrogen or oxygen, but other elements will be missing.
A tad better goes with paper: being made of cellulose fibers, it allows you to get carbon, oxygen, hydrogen.
Therefore if you want to make food for heterothroph beings, you are better off starting from organic wastes, since they bring a more complete set of the needed elements.
Atoms have no memory of where they were before, so the food that you will make in this way, if is has the same composition, will be indistinguishable from the "true" one.
To put it in another way, when farmers use manure to fertilize the ground where they grow trees and crops, the plants will use the atoms contained in the manure to make the apple or the wheat which will end up in the apple pie you are eating right now.