Phenol

This structure is the building bloc of a large group of phenolic compounds (often referred to as polyphenols or simply “phenols”). Phenols are derived mostly from malt and to a lesser degree hops. Yeast produce phenols but the amounts are quite small. Generally speaking, S. cerevisiae produce more phenols than S. uvarum and, wild strains of yeast or bacteria are often the cause of phenolic flavors. Spices used in specialty beers are known to contain phenolic compounds.