Editing Brewing (section)

===Hopback===

A hopback is a traditional additional chamber that acts as a sieve or filter by using whole [[hops]] to clear debris (or "[[Trub (brewing)|trub]]") from the unfermented (or "green") [[wort]],<ref>{{cite book|url=https://books.google.com/books?id=SCg0ct2JKSoC&pg=PT25|page=25|title=Beer: A Gauge for Enthusiasts|author=Greg Duncan Powell|publisher=Allen & Unwin|date=2010|isbn=9781741968132|archive-url=https://web.archive.org/web/20191219200622/https://books.google.com/books?id=SCg0ct2JKSoC&pg=PT25|archive-date=19 December 2019|url-status=live}}</ref> as the whirlpool does, and also to increase hop aroma in the finished beer.<ref>{{cite book|url=https://books.google.com/books?id=gYVLHMmplRcC&pg=PA540|page=540|author=Chad Michael Yakobson|title=The Oxford Companion to Beer|publisher=Oxford University Press|date=9 September 2011|isbn=9780195367133|archive-url=https://web.archive.org/web/20160604055338/https://books.google.com/books?id=gYVLHMmplRcC&pg=PA540|archive-date=4 June 2016|url-status=live}}</ref><ref>{{cite book|url=https://books.google.com/books?id=MonpQW63TKcC&pg=PA127|title=Brewing|page=127|author=Ian Hornsey|publisher=Royal Society of Chemistry|date=2013|isbn=9781849736022|archive-url=https://web.archive.org/web/20160509224128/https://books.google.com/books?id=MonpQW63TKcC&pg=PA127|archive-date=9 May 2016|url-status=live}}</ref> It is a chamber between the brewing kettle and wort chiller. Hops are added to the chamber, the hot wort from the kettle is run through it, and then immediately cooled in the wort chiller before entering the fermentation chamber. Hopbacks utilizing a sealed chamber facilitate maximum retention of volatile hop aroma compounds that would normally be driven off when the hops contact the hot wort.<ref>{{cite book|url=https://books.google.com/books?id=NB8NAQAAIAAJ&pg=PA23|page=23|title=The Brewing Industry: A Guide to Historical Records|author=Peter Mathias|publisher=Manchester University Press|date=1 January 1990|isbn=9780719030321|archive-url=https://web.archive.org/web/20160617050459/https://books.google.com/books?id=NB8NAQAAIAAJ&pg=PA23|archive-date=17 June 2016|url-status=live}}</ref> While a hopback has a similar filtering effect as a whirlpool, it operates differently: a whirlpool uses centrifugal forces, a hopback uses a layer of whole hops to act as a filter bed. Furthermore, while a whirlpool is useful only for the removal of pelleted hops (as flowers do not tend to separate as easily), in general hopbacks are used only for the removal of whole flower hops (as the particles left by pellets tend to make it through the hopback).<ref>{{cite book |url=https://books.google.com/books?id=ciA6-YMTI-UC&pg=PA516 |title=Malting and Brewing Science: Hopped Wort and Beer |pages=516–517 |author1=J.S. Hough |author2=D.E. Briggs |author3=R. Stevens |author4=Tom W. Young |publisher=Springer |date=31 August 1982 |access-date=31 July 2012 |isbn=9780834216846 |archive-url=https://web.archive.org/web/20160603232406/https://books.google.com/books?id=ciA6-YMTI-UC&pg=PA516&lpg=PA516 |archive-date=3 June 2016 |url-status=live }}</ref> The hopback has mainly been substituted in modern breweries by the whirlpool.<ref>{{cite book|url=https://books.google.com/books?id=oWQdjnVo2B0C&pg=PA453|page=453|author=Paul Buttrick|title=The Oxford Companion to Beer|publisher=Oxford University Press|date=9 September 2011|isbn=9780199912100|archive-url=https://web.archive.org/web/20160514132504/https://books.google.com/books?id=oWQdjnVo2B0C&pg=PA453|archive-date=14 May 2016|url-status=live}}</ref>