Changes

Other '''thiol''' (organic sulfur) based compounds contribute to a pleasant aroma and flavor in beer, such as 4-mercapto-4-methyl-pentan-2-one (4MMP), which is found in high quantities in North American varieties such as Simcoe (highest amount), Summit, Apollo, Topaz, and Cascade hops, as well as varieties from Australia and New Zealand. The character of black currant, muscat-like aroma in beer brewed with these hops has been attributed to 4MMP. It is thought that 4MMP is only found in North American, Australian, and New Zealand hops and not European hops because European hops are often treated with copper ions, which has been shown to decrease the amount of 4MMP in hops. Interestingly, beers brewed with these hops showed a 33% increase in 4MMP after fermentation; it is thought that the precursor cysteine conjugate is responsible for the increase in 4MMP during fermentation <ref name="Kishimoto_2008" />. The volatile thiols 3-sulfanyl-4-methylpentan-1-ol (3S4MP; grapefruit <ref name="Cibaka_2016">[https://www.uclouvain.be/cps/ucl/doc/inbr/documents/JAFC_2016_64_8572_8582.pdf 3‑Sulfanyl-4-methylpentan-1-ol in Dry-Hopped Beers: First Evidence of Glutathione S‑Conjugates in Hop (Humulus lupulus L.). Marie-Lucie Kankolongo Cibaka, Laura Decourriere, Celso-JoséLorenzo-Alonso, Etienne Bodart, Raphael Robiette, and Sonia Collin. 2016.]</ref>), and 3-sulfanyl-4-methylpentyl acetate (3S4MPA; passionfruit, grapefruit <ref name="Cibaka_2016" />) have been identified in Nelson Sauvin hops as the compounds that give these hops their "wine-like, Sauvignon Blanc" character. Similar thiols have been described as the major contributors to the aroma of Sauvignon Blanc wines themselves: 3-sulfanylhexan-1-ol (3SH) and 4-methyl-4-sulfanyl-pentan-2-one (4MSP/4MMP) <ref name="Kiyoshi_2009">[http://pubs.acs.org/doi/pdf/10.1021/jf8034622 Identification and Characteristics of New Volatile Thiols Derived from the Hop (Humulus luplus L.) Cultivar Nelson Sauvin. Kiyoshi Takoi, Marie Degueil, Svitlana Shinkaruk, Cécile Thibon, Katsuaki Maeda, Kazutoshi Ito, Bernard Bennetau, Denis Dubourdieu and Takatoshi Tominaga. 2009.]</ref>.

==Characterizing Hop Flavor and Aroma==