13,586
edits
Changes
Hops
,updated to Ag - Oils
Hop oils also generally degrade over time, however, their degradation rates are more complex. [http://pubs.acs.org/doi/abs/10.1021/jf00070a043 Lam et al. (1986)] found that aging both cascade and North American grown Hallertauer Mittelfrueh resulted in an increase in grapefruit-like character, although the compound that caused this was not identified. In the case of Cascade the intensity of this flavor correlated with the age of the hops <ref name="Lam et al., 1986"> [http://pubs.acs.org/doi/abs/10.1021/jf00070a043 Aging of Hops and Their Contribution to Beer Flavor. Lam et al. 1986.] </ref>. In the Hallertauer hops, aging resulted in an increase in a spicy/herbal character <ref name="Lam et al., 1986"/>, which is in agreement with reports of oxidized sesquiterpenes (specifically humulenol II, humulene diepoxides, caryophyllene, and to a lesser extent humulene monoepoxides and alpha-humulene) contributing a spicy/herbal flavor to beer <ref name="Goiris et al., 2002">[http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.2002.tb00129.x/abstract Goiris et al., 2002]</ref><ref name="Mikyška_2012" />. Many of the oils followed in the Lam et al. (1986) study which increased during a short accelerated aging period (2 weeks at 90°F) then decreased during extended aging (60 additional days at 90°F). The cascade hops lost more of the fruity/citrusy hop oils (myrecene, linalool, and geranial) than Hallertauer, suggesting that different strains of hops can withstand aging better than others. The concentration of hop oils are affected by the brewing process and fermentation (see the table) <ref name="Lam et al., 1986"/>. Another study found that beta-ionone (classified as a ketone, and characterized as "floral" and "woody" <ref>[http://www.thegoodscentscompany.com/data/rw1006632.html Beta-ionone. Good Scents Company. Retrieved 11/22/2016.]</ref>) increased in beers brewed with hops that were aged for 30 days at 40°C versus beers brewed with aged hops <ref name="kishimoto_2007" />.
A recent 2017 study at the Shellhammer lab looked at how trained panelists and consumers perceived a lager beer dry hopped with slightly oxidized Hallertau Mittelfrüh hops (exposed to oxygen once, then stored at 38°C for two weeks) versus highly oxidized (daily exposure to oxygen and stored at 38°C for two weeks). They found that the trained panelists detected more characteristics that are associated with noble hops; e.g. more woody, earthy, and herbal characteristics in the lager beers dry hopped with oxidized hops. They also found the oxidized hopped beers to be more bitter (probably due to oxidized alpha and beta acids). Consumers were not statistically able to tell the difference. The study determined that oxidized hops might serve to provide nuanced increases in noble hop character <ref>[http://www.asbcnet.org/publications/journal/vol/2017/Pages/ASBCJ-2017-1287-01.aspx Aroma Properties of Lager Beer Dry-Hopped with Oxidized Hops. Daniel M. Vollmer, Victor Algazzali, and Thomas H. Shellhammer. 2017.]</ref>. In a similar study by Hengyuan et al. (2023), aging Saaz hops for a short amount of time (aged at 30 ℃ in a ventilated environment for 5 days) reduced the grassy and resinous character and improved the spicy and woody character of single hopped beers (hopped at three points in the boil and dry hopped). Consumers also preferred this beer over the other samples, including fresh Saaz. However, over-aging Saaz hops resulted in less preference with consumers (30 ℃ for 10 days, 40 ℃ for 5 days, or 40 ℃ for 10 days). This effect was not demonstrated by Simcoe hops, however, indicating that short aging is only beneficial for some hop varieties. Under the same aging condition with Simcoe hops, consumers preferred the fresh Simcoe, and any degree of aged Simcoe was less preferred. The beers with aged Simcoe hops were described as having less fruity and floral character and more dry, thin bitterness <ref>[https://www.bio-conferences.org/articles/bioconf/abs/2023/04/bioconf_icbb2023_01016/bioconf_icbb2023_01016.html Aging of Hops and Their Effects on India Pale Ale Flavor. Hengyuan Xu, Shaokang Sun, Xiaochen Wang, Haojun Zhang and Cong Nie. BIO Web Conf., 59 (2023) 01016. DOI: https://doi.org/10.1051/bioconf/20235901016.]</ref>.
* [http://scottjanish.com/increasing-bitterness-dry-hopping/ "Increasing Bitterness By Dry Hopping", article by Scott Janish on oxidized alpha acids.]