Humulus lupulus and microbes: Exploring biotic causes for hop creep

Area of Science:

• Brewing Science
• Microbiology
• Enzymology

Background:

• Hop creep is an unresolved issue in brewing, particularly with hops added during fermentation.
• Hops contain dextrin-degrading enzymes, but their origin (plant vs. microbe) is debated.
• A hypothesis suggests microbial dextrin-degrading enzymes cause hop creep.

Purpose of the Study:

• To investigate the origins of hop creep in the brewing industry.
• To identify microbial communities on hops and their potential to produce starch-degrading enzymes.
• To understand hop processing, antimicrobial factors, and microbial resistance mechanisms.

Main Methods:

• Review of hop processing and usage in brewing.
• Analysis of microbial communities on hops.
• Genomic database searches for specific starch-degrading enzymes in identified microbes.
• Investigation of hop antimicrobial factors and bacterial resistance.

Main Results:

• Several bacteria and fungi possess alpha amylase and glycosyl hydrolases.
• Only one identified microbe contains beta amylase.
• The study explored the abundance of these organisms in other flowers.

Conclusions:

• Microbial enzymes are a likely cause of hop creep.
• Specific bacteria and fungi harbor enzymes responsible for dextrin degradation.
• Further research is needed to fully elucidate the microbial contribution to hop creep.