Session Chair:
Tiago Brandão (Innovation & R&D Director Superbock Group, PT)
The effect of barley malt protein on hop bitter acid utilization
By Mariana Barreto Carvalhal Pinto et al., TU Berlin
Binding to protein and subsequent precipitation can lead to a reduced hop bitter acid utilization during wort boiling. This study aimed to identify specific malt protein fractions which show strong binding affinity towards hop bitter acids. Therefore, experiments were carried out to investigate the influence of hop addition on wort protein profile and vice versa, the influence of malt proteins on hop bitter acid content. Hop bitter acids were measured by HPLC, and proteins were quantified and identified by SDS-Page gel electrophoresis followed by LC-MS/MS. Nitrogen content in wort was reduced after boiling in both experiments due to protein precipitation as trub and a negative correlation was found between iso-α-acids and protein content. The protein profile was altered with respect to certain protein fractions in all trials indicating a clear interaction of specific proteins with hop bitter acids. Hence, this study highlights the impact of malt protein composition on the process efficiency, offering breweries higher process control and higher iso-α-acid utilization, e.g. through barley variety selection.
Are small starch granules from barley malt ruining the benefits of high gravity brewing?
By Charlotte F. De Schepper and Christophe M. Courtin, KU Leuven
Breweries use high gravity brewing to improve brewhouse efficiency. However, we believe that the large proportions of small starch granules in barley malt ruin part of this benefit, upsetting the fine balance between starch gelatinization and inactivation of starch-hydrolyzing enzymes during mashing. In this work, the impact of mash thickness on the gelatinization of small and large starch granules was assessed. Thicker mashes resulted in less efficient sugar production, which opposes literature data. We hypothesized that this is due to delayed gelatinization of the small starch granules during mashing, caused by wort components such as sugars. The addition of 24°P wort indeed resulted in a 10°C increase in the starch gelatinization temperature. In the case of small starch granules, this resulted in a peak gelatinisation temperature of 72.5°C. This is problematic, considering that malt β-amylase, producing maltose, is thermally inactivated rapidly at this temperature. In view of these results, the small starch granule proportion in brewing barley and malt should be considered as a selection criterium.
Current research results on the reorientation of European hop cultivation against the background of climatic and political change as well as sustainability requirements
By Walter König, Gesellschaft für Hopfenforschung
Hops is not only one of the oldest medicinal plants, but also an indispensable raw material for beer production. It is often referred to as the “soul of beer”. The international cultivation of hops grown on around 60,000 hectares, with a focus on Europe and the US, is currently facing enormous challenges as a small special culture. Above all, climate change and the increased protection of environmental resources are forcing discussion on the reorientation of hop growing for the future. Main points are the introduction of new research results in methods for more efficient, adequate irrigation and fertilization. Another key issue is the necessary reorientation of pest and disease control as well as a significant intensification of breeding and research to achieve these objectives. Best practices from organic hop production can be transferred, even partially automated, to conventional production. However, new, climate tolerant and disease resistant varieties must also find their way into brewers’ recipes to ensure that the reorientation of hop production is successful and that the sustainable supply of residue-free hops remains guaranteed.