By Harold McGee
Phenolic compounds are constructed from a simple closed ring of six carbon atoms and at least one fragment of a water molecule (an oxygen-hydrogen combination). Single rings can then be modified by adding other atoms to one or more of the carbons, and two or more rings can be linked together to form polyphenolic compounds, including anthocyanin pigments and lignin. Unlike the terpene aromatics, which often have a generic quality to them, the phenolic aromatics are distinctive and define the flavor of such spices as cloves, cinnamon, anise, and vanilla, as well as the herbs thyme and oregano. The pungent components of chillis, black pepper, and ginger are also synthesized from a phenolic base.