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Hops
,split up Dry Hopping and Lacto inhibiting
Dry hopping can contribute to bitterness in beer through oxidized alpha acids and oxidized beta acids. Some alpha acids will also dissolve into the beer, which are estimated as being 10% as bitter as iso-alpha acids. Dry hopping also has a linear impact on the pH of beer regardless of the starting IBU or pH: the pH rises by 0.14 per pound of hop pellets per barrel of beer in a beer that started with a pH of 4.2 (~0.5 ounces per gallon or 3.7 grams per liter) <ref name="Maye_2016" /><ref name="Shellhammer, Vollmer and Sharp, CBC 2015"/>. This rise in pH might be less in more acidic beers that are dry hopped since pH is a logarithmic scale. Dry hopping can also reduce head retention in beers, although this is variety dependent (one study found that dry hopping with Eureka and Apollo hops increased head retention, while dry hopping with Bravo, Centennial, and Cascade decreased head retention). Extended dry hopping times (after 3 days) can also reduce head retention <ref name="Maye_EBC2017" />.
See also:
* [https://www.therarebarrel.com/index.cfm?method=blog.blogDrilldown&blogEntryID=8141D6FA-EE78-5BCE-E08E-704DB6EEA279&originalMarketingURL=blog/Dry-hopped--Changing-process-leads-to-bottling The Rare Barrel reports on an anecdote that dry hopping in a less sour beer extracts better hop aroma, and ''Brettanomyces'' preserves the character.]
* [https://www.facebook.com/groups/MilkTheFunk/permalink/2358742877487246/ MTF thread by Dave Janssen on experiences with doing long-term dry hopping with noble hops in sour beers.] See also [http://www.horscategoriebrewing.com/2018/11/saison-from-1911-finishing-hops-and.html Dave's research on a 1911 saison that was dry hopped long term].
* [https://www.facebook.com/groups/MilkTheFunk/permalink/2718954364799427/ MTF thread on the possibility/mechanism of dry hopping contributing to the "funky" character of sour beers.]
====Inhibiting Lactic Acid Bacteria====
Although the mechanisms are not fully understood, dry hopping inhibits ''Lactobacillus''. Humulinic acids have been found to greatly inhibit bacteria (see [[Hops#Antimicrobial_Properties|Antimicrobial Properties]]). Other compounds such as non-isomerized alpha acids, other acids, or the small amount of isomerization of alpha acids that happens in beer at room temperature <ref>[http://scottjanish.com/zero-hot-side-hopped-neipa-hplc-testing-sensory-bitterness/ Janish, Scott. "Zero Hot-Side Hopped NEIPA | HPLC Testing for Sensory Bitterness". ScottJanish.com. Retrieved 03/09/2017.]</ref>, could contribute to inhibiting lactic acid bacteria. See the links below.
* [https://www.facebook.com/groups/MilkTheFunk/permalink/1416506428377567/?comment_id=1458425540852322&comment_tracking=%7B%22tn%22%3A%22R%22%7D Caroline Whalen Taggart's data point on the effects of dry hopping on ''L. plantarum'' (GoodBelly). No hops finalized at a pH of 3.53, and the dry hopped version finalized at a pH of 4.35.] She used around 4 grams per gallon of 10-15 AA hops <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1746176672077206/?comment_id=1746211618740378&comment_tracking=%7B%22tn%22%3A%22R0%22%7D Carloine Whalen Taggart. Milk The Funk Facebook group. 07/06/2017.]</ref>.
* Per Buer's experiment on the effects of dry hopping on ''Lactobacillus'':
: <youtube width="300" height="200">J2g5P7ZlGn4</youtube>
====The Freshening Power of the Hop (Hop Creep)====