M. BIENDL (1), F. Schuell (2), S. Cocuzza (3);
(1) Hopsteiner HHV GmbH, Mainburg, Germany; (2) Lehrstuhl Brau- und Getraenketechnologie, Freising-Weihenstephan, Germany; (3) Simon H. Steiner, Hopfen, GmbH, Mainburg, Germany
Technical Session 9 - Hop Flavor and Analytics
Wednesday, June 17
8:30–10:15 a.m.
Fiesta 3,4,6,8
The commercial value of hops is particularly influenced by the content of α-acids, the main source of bitter taste in beer. Only recently could the additional positive contribution of hard resins to beer bitterness be clearly demonstrated after isolation of more than 30 single constituents from this fraction with subsequent confirmation of their bitter sensory profile (thesis of Michael Dresel, 2013). Based on spiking experiments in the laboratory, at least 20% of the hop-derived beer bitter intensity was attributed to hard resins and around 75% to iso-α-acids. Now the goal was to verify the practical impact of these findings by comparing the bitterness impressions resulting from different hard resin-containing hop products in brewing trials (6 hL). Single-hopped lager beers were produced in duplicate using pellets, ethanol extract, or a special product, enriched in hard resins, all from the hop variety Hallertau Taurus, crop 2013. The beers were evaluated by chemical (LC-MS/MS and GC-MS) and sensorial (two trained panels) analyses. Single constituents like xanthohumol, isoxanthohumol, or co-multifidol glucoside, which are typical for the hard resin fraction, were present in all the different beers. Their concentrations were almost identical in the case of pellets and ethanol extract but at least a factor of three higher in the case of the hard resin-enriched product. However, the taste panels detected no significant differences between the various beers, even when the so-called “duo/trio test” was performed. The fact that the variant of using the special product also resulted in comparable quality confirms a positive impact of hard resins. This product was the residual bitter fraction after re-extracting ethanol extract with supercritical carbon dioxide. It contained the whole range of hard resin constituents that are carried over from hops, pellets, or ethanol extract during the brewing process. Thus their beneficial influence on the bitter taste of beer could be verified in this study. Moreover, this fraction consists of single compounds supporting the positive image of beer with regard to health aspects as, for example, recently discussed in the scientific paper “American India Pale Ale Matrix Rich in Xanthohumol is Potent in Suppressing Proliferation and Elevating Apoptosis of Human Colon Cancer Cells” (published in 2014). Considering both their contribution to the bitterness and to the health image of beer makes it evident that evaluating the hard resins as an important hop fraction has value for the brewing industry.
Martin Biendl is a chemist (Ph.D. degree in 1990) and R&D manager at the German site of the global Hopsteiner group, a hop trading and processing company. He is the representative of the International Hop Industry Cooperation (IHIC) on various analysis committees of the international hop and brewing industry and he is a board member of the German Hop Trade Association.
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