Varietal specificity of polyphenols, free phenolics and antioxidant potential in hops

Abstract

Many studies have confirmed hops (Humulus lupulus L.) as the source of a number of physiologically active polyphenols, important for both brewing and potentially pharmaceutical purposes. The three-year screening of polyphenols and 23 free phenolics profile (HPLC/coulometric detection) showed a significant association of polyphenols and free phenolics with DPPH antioxidant potential and the genetically determined specificity of free phenolics composition in hops. Varieties of American origin have a different profile compared to European varieties. For the first time, the free phenolics hydroxycoumarins were detected in hops. The DPPH strongly correlated with total polyphenols and flavanoids (n = 95, r = 0.92, 0.93 respectively) and correlated negatively with alpha acids (n = 95, r = -0.73). The polyphenols and the DPPH decrease with increasing alpha acids both among varieties and within one variety. These findings can serve as a useful tool for hop selection in brewing or pharmaceutical production.