Searching the world of hops and brewing to bring you the latest news and research ... so you don‘t have to!
If yeast starts to pretend to be hops
Yes, there are some studies that report that yeast wants to compete with hops, e.g. to produce certain aromatic substances that were previously attributed to hops. In this context, I think yeast and hops can simply work together without outcompeting each other. But if yeast can help to produce hop flavonoids, then it will admittedly be interesting. The flavonoid xanthohumol is an important flavor substance in the brewing industry that has a wide variety of bioactivities. However, its unstable structure results in its very low content in beer. Microbial biosynthesis is considered a sustainable and economically viable alternative. Here, a Chinese Research Team used the yeast Saccharomyces cerevisiae for the de novo biosynthesis of xanthohumol from glucose by balancing the three parallel biosynthetic pathways, prenyltransferase engineering, enhancing precursor supply, constructing enzyme fusion, and peroxisomal engineering. These strategies improve the production of the key xanthohumol precursor demethylxanthohumol (DMX) by 83-fold and achieve the de novo biosynthesis of xanthohumol in yeast. This work provides feasible approaches for systematically engineering yeast cell factories for the de novo biosynthesis of complex natural products.
Yang S, Chen R, Cao X, Wang G, Zhou YJ. De novo biosynthesis of the hops bioactive flavonoid xanthohumol in yeast. Nat Commun. 2024 Jan 4;15(1):253. doi: 10.1038/s41467-023-44654-5. PMID: 38177132; PMCID: PMC10766616.
A more sustainable usage of hops in brewing
In the last decade, production of hop forward dry hopped beers increased considerably. Dry hopping results in significant amounts of spent hop vegetative matter, which is mostly regarded as waste and is therefore discarded. During dry hopping, polar aroma compounds are extracted into beer, while non-polar compounds such as humulones largely remain in the spent hops. These German Researchers used spent hops from local craft breweries. The spent hops were analysed for dry matter, surplus beer content, their concentration of humulones, and iso-humulones. Theywere then used for bittering a pilsner beer. It was found that humulone concentrations in spent hops ranged from 1 to 10% dry matter, which corresponds to retention rates of 28 to 94%. Wort and beer samples made from selected spent hop samples were analysed using a range of physicochemical analyses. Beer analysis showed that the targeted bitterness (30 BU) was successfully achieved in most brews only using spent hop material. Sensory analysis confirmed the good overall quality of spent hop beers as such and also in comparison with a reference brew using hop pellets. In summary, spent hops can substitute at least a part of the hop pellets used in the kettle and the environment would say thank you.
Schrickel, F., Bilge, D., Pahl, R., & Rettberg, N. (2024). Valorization of Spent Hops from Dry Hopping for Bittering of Pilsener Style Beer. Journal of the American Society of Brewing Chemists, 1–13. doi.org/10.1080/03610470.2024.2327123
How can we fill the flavor gap in non-alcoholic beers? – Guess what, hops!
Currently, non-alcoholic beers and low-alcoholic beers (NABLABs) suffer from premature oxidation when fresh, and from a lack of fruity fermentation aromas. In wines, dimethylsulfide (DMS) is known to enhance fruity characters. This offers an opportunity to improve the flavor of NABLABs. These Belgium Researchers assessed the levels of free DMS and its potential precursors (S-methylmethionine/SMM and dimethylsulfoxide/DMSO) in eleven commercial NABLABs, in parallel with their amounts of fruity esters and polyfunctional thiols. Except in two dry-hopped samples and a fruity beer, free DMS was detected at very low levels in all fresh NABLABs (four samples even displayed no detectable GC peak), likely because of dealcoholization or too short of a fermentation. Through NABLABs aging, the free DMS concentration increased at a degree correlated with the initial SMM level (2–118 µg/L). This SMM amount revealed to be also correlated with those amino acids that are more consumed through fermentations. Unlike DMSO, SMM showed significant release of free DMS after aging in spiking experiments. As fruity fermentation esters are found in NABLABs at much lower concentrations than in conventional lagers, increasing both DMS and polyfunctional thiols by dry hopping is an opportunity to improve them.
Simon, M., & Collin, S. (2024). Increasing Dimethylsulfide and Polyfunctional Thiols, an Opportunity to Enhance the Fruity Flavors of NABLABs. Journal of the American Society of Brewing Chemists, 1–12. doi.org/10.1080/03610470.2024.2319930
