How Barley Proteins Affect Hop Bitterness in Beer Brewing

Jenn Hoskins
19th September, 2024

How Barley Proteins Affect Hop Bitterness in Beer Brewing

Image Source: Natural Science News, 2024

Key Findings

  • The study by the University of Campinas (UNICAMP) examined how different barley cultivars affect hop bitter acid utilization during wort boiling
  • Researchers found that the barley cultivar Liga resulted in significantly lower α- and iso-α-acid content in the wort compared to the Solist cultivar
  • The study identified 107 protein groups with significant differences between the two barley cultivars, highlighting the importance of barley selection in optimizing brewing processes
Efficient utilization of hop bitter acids is a persistent challenge in brewing, with approximately 50% of these compounds precipitating with trub during wort boiling. A recent study conducted by the University of Campinas (UNICAMP)[1] aims to uncover the correlation between the barley cultivar proteome and hop bitter acid utilization during wort boiling. This research provides insights that could enhance brewing efficiency and beer quality. The study compared two barley cultivars, Liga and Solist, to identify specific proteins' roles in hop bitter acids precipitation. High-performance liquid chromatography (HPLC) was used to measure hop bitter acid content, while liquid chromatography-tandem mass spectrometry (LC-MS/MS) quantified and identified proteins. The results revealed significant differences in the proteomes of the two cultivars, particularly in enzymes linked to barley metabolic defense mechanisms. Notably, wort produced from the barley cultivar Liga exhibited significantly lower α- and iso-α-acid content. This research builds on previous studies that have explored various aspects of brewing science. For instance, a detailed study on hop alpha-acid isomerization kinetics[2] found that iso-alpha-acid formation follows first-order kinetics and Arrhenius behavior. Differences in activation energies for the formation of trans- and cis-isomers were also noted. These findings are crucial for understanding the chemical behavior of hop acids during wort boiling and their interaction with other wort components. Another relevant study examined the dynamic proteome of barley during malting[3]. This research identified 1418 proteins across five malting stages, with significant differences in protein abundance. Proteins associated with carbohydrate metabolism and enzyme activity regulation were highlighted as novel targets for malting barley breeding. This proteomic data provides a foundation for understanding how barley cultivar selection can influence brewing outcomes. The role of hop bitter acids in protein aggregate formation has also been investigated[4]. This study used a proteomic approach to analyze wort protein composition before and after boiling. It was found that hop bitter acids bind primarily to less abundant proteins, which are not related to beer quality traits such as foam or haze. These interactions likely contribute to the loss of hop bitterness during wort boiling. The current study expands on these findings by directly linking barley cultivar proteome to hop bitter acid utilization. The identification of 107 protein groups with significant differences between Liga and Solist cultivars underscores the importance of barley selection in optimizing brewing processes. By selecting barley cultivars with favorable proteomes, brewers can enhance hop utilization and improve beer quality. In summary, the research conducted by UNICAMP highlights the critical role of the barley proteome in hop bitter acid utilization during wort boiling. By integrating findings from previous studies on hop isomerization kinetics[2], barley malting proteomics[3], and hop-protein interactions[4], this study provides a comprehensive understanding of the factors influencing hop utilization in brewing. The insights gained from this research could lead to more efficient brewing processes and higher quality beer.

AgricultureBiochemPlant Science

References

Main Study

1) The Influence of Barley Proteome on Hop Bitter Acid Yield during Brewing.

Published 16th September, 2024

https://doi.org/10.1021/acs.jafc.4c04396

Related Studies

2) A kinetic study on the isomerization of hop alpha-acids.

https://doi.org/10.1021/jf8004965

3) Temporal Analyses of Barley Malting Stages Using Shotgun Proteomics.

https://doi.org/10.1002/pmic.201800025

4) Addition of Hop (Humulus Lupulus L.) Bitter Acids Yields Modification of Malt Protein Aggregate Profiles during Wort Boiling.

https://doi.org/10.1021/acs.jafc.3c00185


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