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Target profiling of beer styles by their iso‐α‐acid and phenolic content using liquid chromatography–quadrupole time‐of‐flight–mass spectrometry

“…Homologs of α-acids include cohumulone, n-humulone, and adhumulone, which differ only in the nature of the saturated acyl side chain [6]. When hops are added during the boiling stage of brewing, the α-acids become thermally isomerized to produce trans-and cisstereoisomers of iso-α-acids (isocohumulone [iCH], isohumulone [iH], and isoadhumulone [iAH]) [7]. The IAAs are major contributors to the characteristic bitter flavor of beer, with the cis-isomers generally contributing more bitterness than the trans-isomers [8].…”

“…The IAAs are major contributors to the characteristic bitter flavor of beer, with the cis-isomers generally contributing more bitterness than the trans-isomers [8]. The light stability of beer can be improved by converting IAAs to their reduced forms by hydrogenation and reduction reactions [7]. The three types of reduced IAAs include dihydro-iso-α-acid (also called "rho", [ρ]-), tetrahydro-iso-α-acid, and hexahydroiso-α-acid (RiAA, TiAA, and HiAA, respectively), which differ by the number of hydrogen atoms incorporated during reduction (Supporting Information Figure S1) [8].…”

“…Polyphenols and phenolic acids primarily originate from barley and hops and contribute to the flavor, color, body, and colloidal stability (i.e., haziness) of beer [7][8][9]. While some phenols add desirable flavor characteristics, such as clove in a Hefeweizen, others create unwelcome offflavors.…”

“…Due to their significant impact on flavor and stability, the IAAs and phenols in beer have been studied extensively [14][15][16][17], but primarily in the context of their contributions to bitterness [7,18]. This study aims to simultaneously analyze the IAAs and phenolic compounds in beer using LC-Q-TOF-MS and to use the chemical profiles to distinguish between the flavor characteristics of various U.S. beer styles.…”