Searching the world of hops and brewing to bring you the latest news and research ... so you don‘t have to!
Clean up with the seed myth!
Brewers love this topic! Hop seeds, what are they doing to the beer? The EU certification system distinguishes between seedless and seeded hops. The vast majority of hops produced within the EU belong to the category of hops without seeds, which allows a maximum seed content of 2 % (w/w). Not so in the UK were male plants are kept in the hop garden. The myth is the assumption that hop seeds, full of lipids, ruin the beer foam and flavour stability. In this study the impact of hop seeds on beer quality was assessed through brewing trials. Lager beers were produced with additions of 50 and 70 g/hl (which is a lot!) hop seeds during wort boiling and after primary fermentation. The addition of hop seeds showed no measurable effects on foam stability or sensory properties. Even in long-term storage tests (6 months at 30 °C), no differences in quality were detected between beers brewed with and without seeds. The only noticeable change was a slightly increased alcohol content, likely resulting from amylolytic enzyme activity in the seeds. So I am sorry this myth has to go into the drawer of fairy tales. Hop seeds are not bad for beer. Male hop plants are socially acceptable again.
Schüll, F., Forster, A., & Gahr, A. (2025). Influence of hop seeds on the analytical properties and sensory quality of beer. BrewingScience, 78(11/12), 118-125. https://doi.org/10.23763/BrSc25-17schuell
Hopoil is safe
You probably come across this phrase before: “Generally Recognized as Safe (GRAS)” is a U.S. Food and Drug Administration (FDA) designation for food additives or ingredients considered safe by qualified experts for their intended use. It exempts these substances from the, typically, rigorous premarket approval process required for new food additives. GRAS, established by the 1958 Food Additives Amendment, covers common items like spices and preservatives. As part of the Expert Panel of the Flavor and Extract Manufacturers Association’s (FEMA) program to evaluate the safety of flavor ingredients several natural flavor complexes (NFCs) whose constituent profiles are characterized by mono- and sesquiterpene hydrocarbons were reevaluated. Using the Panel’s safety evaluation procedure, the constituents of each NFC were organized into congeneric groups that are defined by similar structural properties and shared metabolic and toxicological properties. By application of the Panel’s safety evaluation procedure for NFCs, it was shown that the estimated intakes for the constituent congeneric groups for each NFC were below the Threshold of Toxicological Concern (TTC) indicating no safety concern for consumers, including children. Hop oil was part of this evaluation, along with ginger extract, black pepper oil, and several others. So, keep calm and add more hop oil.
Hecht SS, Cohen SM, Eisenbrand G, Fukushima S, Gooderham NJ, Guengerich FP, Rietjens IMCM, Rosol TJ, Davidsen JM, Harman CL, Taylor SV. FEMA GRAS assessment of natural flavor complexes: Pepper, ginger, coniferous-derived and related flavoring ingredients. Food Chem Toxicol. 2025 Dec 11:115849. doi: 10.1016/j.fct.2025.115849. Epub ahead of print. PMID: 41390051.
Life on planet hops
Dry hopping is widely used in craft brewing but introduces non-sterile hop material that could bring microorganisms into beer. Although beer is typically viewed as microbiologically stable, recent studies show hops may contain live fungi and bacteria that could impact beer quality. This study explored the fungal DNA found in commercial hop pellets and how it transfers during dry hopping. By applying ITS2 metabarcoding (a molecular technique that uses DNA sequencing to identify multiple species within a mixed environmental sample). The hop pellets included a range of fungi, mostly common leaf endophytes, along with yeast types related to fermentation or spoilage, such as Saccharomyces, Wickerhamomyces, Rhodotorula, and Debaryomyces. Most fungi only appeared in hops, but four genera—Wickerhamomyces, Vishniacozyma, Bipolaris, and Curvularia—were also present in the dry-hopped beer yet absent in unhopped samples, suggesting they were introduced by the hops. Metabolomic analysis showed dry hopping not only increased certain hop-related metabolites but also altered the aroma profile by boosting ethyl esters, higher alcohols, and short-chain fatty acids. So if this increased community of microorganisms really impacts the aroma profile of dry hopped beers we have to overthink our understanding of biotransformation.
Molnár A, Lovas M, Kiss T, Knapp DG, Lepres LA, Váczy KZ, Geml J. From hop (Humulus lupulus L.) to beer: hop pellets as fungal vectors in dry-hopped craft beers. FEMS Microbiol Lett. 2025 Jan 10;372:fnaf138. doi: 10.1093/femsle/fnaf138. PMID: 41369910.
