Comparative study of the contribution of hop (Humulus lupulus L.) hard resins extracted from different hop varieties to beer quality parameters

Hop (Humulus lupulus L.) hard resin is mainly composed of deterioration products that arise by oxidation of the soft resin (mainly α- and β-acids). The prenylated chalcone xanthohumol is also naturally found in the hop hard resins. To date, no clear distinctions have been made among the brewing properties of hard resins extracted from different hop varieties. Hard resins extracted from bittering and aroma hops were compared and rated based on their brewing value and their contributions to beer quality. Brewing trials were conducted in which hop pellets were replaced with resin-rich extracts and added to the wort at different time points. It was thereby possible to evaluate and establish the brewing potential of the hop hard resin as well as the varietal impact and the effect of the hopping technology. The sensory evaluations of the beers proved that hard resins have a positive impact on taste and bitterness. The data indicated that the hard-resin brews are not only influenced by the hop variety used but also by the boiling regime applied. Hard resins from bittering hops showed better brewing properties than those extracted from the aroma variety.