Searching the world of hops and brewing to bring you the latest news and research ... so you don‘t have to!
Still creepy under pressure
In recent years, much has been learned about hop creep and how to manage this unplanned additional fermentation process brewers experience during dry hopping. But there is more to learn. This research group from Poland proved that the presence of live active yeast is a prerequisite for the occurrence of hop creep. In pasteurized beer samples, the phenomenon simply did not occur. On the other hand, in non-pasteurized beer samples, dry hopping caused a significant decrease in the apparent extract of the beer. In addition, hop creep was shown to be a continuous process; separation of the hops from the beer stopped this process and no further decrease in apparent extract was observed. Overall, on a pilot and industrial scale, a decrease in apparent extract was observed in all dry-hopped beers, regardless of style and type of yeast used, varying between 0.8-1.2% w/w. Depending on the beer style, the duration of hop creep varied from 8-10 days for top fermented beers and from 14-15 days for bottom fermented beers. The applied pressure in the tank (0.1 MPa) prolonged the hop creep process by 6 days, but did not affect the final attenuation. It stays creepy I would say.
Hrabia, O., Poręba, P., Ciosek, A., & Poreda, A. (2024). Effect of Dry Hopping Conditions on the Hop Creep Potential of Beer. Journal of the American Society of Brewing Chemists, 82(4), 412–421. https://doi.org/10.1080/03610470.2024.2388430
Lactic acid bacteria and hops may eventually become friends..
The presence of hops can be a limiting factor in the production of sour beers. These beers are characterized by their extraordinary complexity, brought about by lactic fermentation driven by lactic acid bacteria (LAB). Most lactic acid bacteria are very sensitive to hops, especially to the iso-alpha acids formed during hop boiling, as well as some other soluble hop compounds. Some brewing relevant bacteria, including Lactobacillus and Pediococcus species, can develop resistance to hops and become quite resistant over time. This study includes a comparative analysis of the viability of Lacticaseibacillus paracasei subsp. paracasei F19 (F19) and 431 (L431) in a sour beer with IBU value of 22, as well as the expression of a number of genes which are associated with hop resistance. The results suggest that both probiotic strains of F19 and L431, are well-suited for the production of sour beers with elevated hop content and show excellent product stability. In particular, the expression of genes responsible for hop resistance showed different modulation patterns between the two strains. It appears that a higher concentration of the bsrA-gene, as observed in strain L431, may be more effective in mitigating the effects of hop-related stress. However, further research is needed to validate this observation in gene expression. For now, F19 and L431appear to be promising candidates for the development of sour beers with increased hop intensity.
Herkenhoff, M. E. (2024). The Probiotic Paradox: Thriving in High-Hopped Sour Beer. Journal of the American Society of Brewing Chemists, 82(4), 422–430. https://doi.org/10.1080/03610470.2024.2350108
Do brewers have to rethink DMS?
Brewers don't like DMS, it's considered an off-flavor and they will do almost anything to get it out of the beer during the entire brewing process. Dimethyl sulfide (DMS) is formed by the thermal decomposition of SMM S-methylmethionine, which is a precursor found in malted barley. In addition, during fermentation, yeast can reduce another precursor, dimethyl sulfoxide (DMSO), to DMS. This reaction depends on the yeast strain used and the fermentation conditions. To control DMS levels in beer, brewers can take several steps, such as selecting malts with lower SMM content, ensuring vigorous boiling to drive off DMS, and maintaining proper fermentation conditions to minimize DMS formation. However, these measures may not be beneficial for non-alcoholic beers. Usually, non-alcoholic beers and low-alcoholic beers (NABLABs) suffer from a lack of flavor in general and of fruity fermentation aromas in particular. As we know from wine, dimethyl sulfide (DMS) can enhance truffle nuances and fruity character. This provides an opportunity to improve the flavor of NABLABs. This research group from Belgium evaluated the levels of free DMS and its potential precursors (S-methylmethionine/SMM and dimethylsulfoxide/DMSO) in eleven commercial NABLABs, in parallel with their levels of fruity esters and polyfunctional thiols. With the exception of two dry-hopped samples and a fruity beer, free DMS was detected at very low levels in all fresh NABLABs. As the NABLABs aged, the free DMS concentration increased to a degree that correlated with the initial SMM level (+63% on average after two years). This SMM level was also found to correlate with the group I amino acid content (more consumed by traditional fermentations). Unlike DMSO, SMM showed a significant release of free DMS after aging in spiking experiments. Since fruity fermentation esters are found at much lower concentrations in NABLABs than in conventional lagers, increasing both DMS and polyfunctional thiols by dry-hopping is an opportunity to improve their flavor. Yes DMS can be a brewer’s friend – be tolerant!
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, 82(4), 431–442. https://doi.org/10.1080/03610470.2024.2319930