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Hops
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A Masters thesis by Tanriverdi (2024) demonstrated that that longer contact times of hops in beer significantly promoted enzymatic activities involved in glucose production, maltose degradation and isoamyl acetate hydrolysis. The same observations were evidenced at higher temperatures. It was noted that a dry heat treatment of hops prior to incubation revealed to reduce the release of glucose and the hydrolysis of isoamyl acetate. Surprisingly, only a high dosage of 10% v/v ethanol in beer resulted in inhibition of amylolytic enzymes. For this dosage, esterase activity remained intact. Concerning the influence of hop variety, only amylolytic enzymes of Simcoe hops exhibited pronounced activities compared to other varieties. Finally, cryo pellets exhibited lower enzymatic activities compared to T90 pellets and whole cones, which indicates that enzymes could be mainly found in vegetative material <ref>[https://dial.uclouvain.be/memoire/ucl/en/object/thesis%3A48802 Tanriverdi, Yudum. Influence of the residual enzymatic power of hops added during fermentation and/or maturation on beer stability. Faculté des bioingénieurs, Université catholique de Louvain, 2024. Prom. : Collin, Sonia ; Willemart, Guillaume.]</ref>. A second study by Tanriverdi et al. (2025) reported that op T90 pellets that were were baked in an oven at 100°C for 40 min had no significant enzymatic activity while hops that did not undergo this treatment exhibited significant enzymatic activity from the dry hops (both hydrolysis of isoamyl acetate via esterases and an increase in glucose and maltose via α-amylase, β-amylase, limit dextrinase, and α-glucosidase). In addition, they confirmed that longer contact time with dry hops (1-3 weeks) increased the enzymatic activity. Warmer conditions also increased this activity (24°C vs 50°C). Again, they saw limited enzymatic activity when ethanol was at 10%, indicating that high ABV beers should be less affected by dry hop creep <ref>[https://www.tandfonline.com/doi/full/10.1080/03610470.2024.2432146 Willemart, G., Tanriverdi, Y., & Collin, S. (2025). Impact of Contact Time, Temperature, and Ethanol Content on Hop Creep-Related Enzymatic Activities in Beer. Journal of the American Society of Brewing Chemists, 1–7. https://doi.org/10.1080/03610470.2024.2432146.]</ref>.
[https://www.tandfonline.com/doi/full/10.1080/03610470.2024.2388430 Hrabia et al. (2024)] demonstrated several conditions that encourage of discourage dry hop creep. They demonstrated that pasteurized beer does not demonstrate hop creep due to yeast being killed during the pasteurization process. It was also demonstrated that separating the hops plant material from the beer after 3 days reduced the effect of dry hop creep. Microbiological analysis shows that if there were any microorganisms on the hops, no beer spoilers such as ''Brettanomyces'' were found that could have over-attenuated the beers that suffered from dry hop creep. The duration of the hop creep in hazy IPA's was faster than in a cold IPA; this was hypothesized to be caused by lower fermentation temperatures of the cold IPA, mashing regiment, or being a bottom fermented beer (lager). They also demonstrated that fermenting under head pressure slows the effect of dry hop creep, but given enough time, non-pressure and pressure fermentation will reach the same final gravities <ref>[https://www.tandfonline.com/doi/full/10.1080/03610470.2024.2388430 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.]</ref>.
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