Properties of Dry Hopped Dark Beers with High Xanthohumol Content

Abstract

The antioxidant activity of beers comes mainly from phenolic compounds and melanoidins. The aim of this research was to evaluate the effect of technological operations, especially the ethanol fermentation process using top fermentation brewer’s yeast Saccharomyces cerevisiae, on the antioxidant activity of dark dry hopped beers with a high xanthohumol content. Four beers were produced using different varieties of hops. The polyphenol content during beer processing increased at the stage of hopping and fermentation, while it decreased during aging. The ability to reduce iron ions increased for all beers compared to hopped wort. The opposite tendency was noted for the antioxidant capacity expressed as the ability to reduce the radical cation ABTS•+ generated from 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid). Fermentation and aging caused a decrease in beer color intensity. The content of 5-hydroxymethylfurfural (5-HMF) increased with the color intensity of wort, therefore in beers no presence of 5-HMF was observed. The beers were characterized by a distinctly high content of xanthohumol in the range of 1.77–3.83 mg/L and 0.85–1.19 mg/L of isoxanthohumol. The content of prenylflavonoids and bitterness of beer depended on the variety of hops used.

Characteristics of New England India Pale Ale Beer Produced with the Use of Norwegian KVEIK Yeast

“…A decreased concentration of phenolics after aging confirms results of earlier studies [ 13 ]. In contrast, the activity of yeast esterase of ferulic acid leads to the release of phenolic acids during primary and secondary fermentation, and aging, which may result in their increased content [ 17 ].…”

“…The antioxidative activity of beer is mainly ascribed to the phenolic compounds of malt and hop and to melanoidins produced during heat treatment of malt, mash, and brewing wort [ 13 ], as well as to additives, mainly fruits [ 14 , 15 , 16 ]. The content of phenolic compounds affects the key quality attributes of beer, i.e., clarity, color, and taste, as well as its storage stability [ 17 ].…”

“…The content of phenolic compounds of beers changes over the technological process. Its increase is observed during wort hopping, main fermentation, and post-fermentation [ 13 ].…”

Yeast Strains and Wort Color as Factors Affecting Effects of the Ethanol Fermentation Process

“…The conditions of the technological process of beer production contribute to a number of changes in the composition of phenolic compounds, which are related to the temperature of the processes, active enzymes of malt, hops, or bioprocesses that occur with microorganisms during fermentation [10][11][12]. As evaluated in our previous studies [11], TPC in beers increases during the hopping and fermentation stages, while it decreases after maturation. According to Fumi et al [13], fermentation leads to a 16% decrease in TPC due to the adsorption of phenolic compounds on the surface of negatively charged yeast cell walls.…”

“…As the color of the brewing wort darkens, TPC and the antioxidant activity increase [6]. The conditions of the technological process of beer production contribute to a number of changes in the composition of phenolic compounds, which are related to the temperature of the processes, active enzymes of malt, hops, or bioprocesses that occur with microorganisms during fermentation [10][11][12]. As evaluated in our previous studies [11], TPC in beers increases during the hopping and fermentation stages, while it decreases after maturation.…”