Acylphloroglucinol Glucoside from Hops: Isolation, Identification and Haze-activity

Abstract

Polyphenols can complex with proteins in the beer matrix, thereby forming undesirable temporary or permanent hazes. Conversely, polyphenols possess desirable qualities as they are antioxidants and have health benefits. Selectively removing haze-sensitive polyphenols can therefore be an important tool for optimising beer quality. In this study, one predominant compound was detected in PVPP washing solution as well as unfiltered beer and thus was suspected of being able to form haze. The compound was isolated from a hop tannin extract by using preparative HPLC and subsequently identified as 1-[(2-methylpropanoyl)-phloroglucinyl]-β-D-glucopyranoside (co-multifidol glucoside) by NMR (1H, 13C and 2D) coupled with MS. In separate trials using model solutions, its tendency to form haze was confirmed. As a complement, various phenolic compounds from the hop tannin extract and the co-multifidol glucoside were identified by using HPLC-DAD.