At Brunswick Labs we adopted from the Folin-Ciocalteau method which was initially intended for the analysis of proteins taking advantage of the reagent’s activity toward protein tyrosine (containing a phenol group) residue. Many years later, Singleton and co-workers extended this assay to the analysis of total phenols in wine. The FC-based assay gained popularity. The FC actually measures a sample’s reducing capacity, but this is not reflected in the name “total phenolic” assay? Despite the undefined chemical nature of FC, the total phenols assay by FC is convenient, simple, and reproducible. As a result, a large body of data has been accumulated, and it has become a routine assay in studying phenolic antioxidants.