Changes

Freshly harvested hops should be dried first, as is normal for hop processing, before aging to help prevent [[Mold|mold]] growth (see this [https://www.canr.msu.edu/news/drying_hops_on_a_small_scale article from Michigan State University] on measuring moisture levels and [https://www.homebrewersassociation.org/how-to-brew/how-to-harvest-prepare-and-store-homegrown-hops/ this AHA article on drying hops] for home growers). Typically, only low alpha acid hops are used (high alpha acid hops may lead to more hop character and higher inhibition of lactic acid bacteria than desired). The hops are typically bound in burlap sacks or a similar bag material that allows for exposure to oxygen, and then they are left to age in preferably low humidity conditions at room temperatures to warm temperatures (warmer temperatures will encourage faster aging). Changes in the environment such as temperature shifts are not a big concern; for example [https://web.archive.org/web/20180204131402/http://jesterkingbrewery.com/home-for-our-aged-hops Jester King Brewery in Austin Texas ages hops in a horse barn]. The hops should be are traditionally aged for 2+ years. Monitor for mold growth during this time, and discard any hops that show visible signs of mold growth. Some brewers prefer to age the hops until the cheesy character ([[Isovaleric Acid]]) is gone, while other brewers do not mind the presence of this cheesy character. While hop leaves are generally preferred over pelletized hops, if aging pellets, it has been advised to break the pellets up so that the entirety of the hop material is exposed to the air.