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====The Freshening Power of the Hop (Hop Creep)====
Also known as "dry hop creep", it was first discovered in 1893 by Brown and Morris that dry hopping increases the ABV of beers and dries them out. Dry hop creep, along with the secondary fermentation of ''Brettanomyces'' in long aged British ales of the late 19th and early 20th centuries, were once characterized as the potential mechanisms by which long aged ales could retain a high level of carbonation in casks <ref>[https://archive.org/details/principlespracti00syke "The principles and practice of brewing" Sykes, Walter John. London, C. Griffin and Company, limited, 1907. Pgs 384-388.]</ref><ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/4709953772366133 Gareth Young. Milk The Funk Facebook group thread about English brewers historically relying on Brettanomyces and dry hop creep for carbonation in long aged ales. 06/17/2021.]</ref>. It was proposed that the likely cause is the release of glycolytic enzymes that break down starches into sugars which viable yeast can then ferment. Brewers normally aim to control the final alcohol percentage in a beer through brewhouse operations rather than postfermentation dilutions with lower/higher alcohol beers or water. This approach to brewing is called "brewing to final gravity." Due to the need to have a predictable ABV for government regulatory reasons, unexpected fermentation is, therefore, a concern for many breweries <ref name="Kirkendall_2018">[https://www.tandfonline.com/doi/abs/10.1080/03610470.2018.1469081?journalCode=ujbc20 The Freshening Power of Centennial Hops. Jacob A. Kirkendall, Carter A. Mitchell & Lucas R. Chadwick. 2018. DOI: https://doi.org/10.1080/03610470.2018.1469081.]</ref>. Hop creep can also result in additional attenuation and higher carbonation after packaging, as well as diacetyl production.
Historically, there have been two studies published on the phenomenon of hops releasing glycolytic enzymes that break down starches during dry hopping: [http://barclayperkins.blogspot.com/2018/03/why-dry-hop.html Brown and Morris (1893)] and [https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.1941.tb06070.x Janicki et al. (1941)]. More recently, several researchers and brewers have revisited this phenomenon. Brown and Morris (1893) discovered that hops could break down maltodextrin, but failed to identify the enzymes from the hop plant material and hypothesized (probably incorrectly) that tannins were inhibiting the enzymes. Janicki et al. (1941) came to similar conclusions regarding the enzymes and tannin inhibitors, and they also concluded that the enzyme activity was independent of hop variety, geography, age, storage conditions, pH values between 4.1 and 4.8, and that one or more additional unknown factors were at play <ref name="Kirkendall_2018" />.