Alpha acids (
![](https://upload.wikimedia.org/wikipedia/commons/thumb/5/5f/%28S%29-Humulone.svg/220px-%28S%29-Humulone.svg.png)
Alpha acids may be isomerized to form iso-alpha acids by the application of heat in solution. Iso-alpha acids (iso-
The degree of isomerization and the amount of bitter flavor produced by the addition of hops is highly dependent on the length of time the hops are boiled. Longer boil times will result in isomerization of more alpha acids and thus increased bitterness.
Common alpha acids include humulone, adhumulone, cohumulone, posthumulone, and prehumulone. The most common iso-
Bittering
editThe alpha acid "rating" on hops indicates the amount of alpha acid as a percentage of total weight of the hop. Hops with a higher alpha acid content will contribute more bitterness than a lower alpha acid hop when using the same amount of hops. High alpha acid varieties of hops are more efficient for producing highly bitter beers.
Alpha acid percentages vary within specific varieties depending on growing conditions, drying methods, age of the hop, and other factors. For example, this list shows the typical range of alpha acids found in some common varieties (percentages are based on total dried weight).[2]
Hop Variety | Alpha Acid Content |
---|---|
Saaz | 2 - 5% |
Hallertauer Hersbrucker | 2.5 - 5% |
Mt. Hood | 3.5 - 8% |
Willamette | 4 - 7% |
Styrian Goldings | 4.5 - 7% |
East Kent Goldings | 4.5 - 7% |
Cascade | 4.5 - 8% |
Centennial | 9 - 11.5% |
Chinook | 12 - 14.0% |
The choice of a hop variety used in beer brewing depends on the beer style. For instance, lager styles use hop varieties with a low alpha acid content (such as Saaz and Hallertauer) while IPA styles use hop varieties with a high alpha acid content (such as Cascade, Centennial and Chinook).
Anti-bacterial properties
editIso-
The iso-
References
edit- ^ Urban, Jan; Dahlberg, Clinton; Carroll, Brian; Kaminsky, Werner (2013). "Absolute Configuration of Beer′s Bitter Compounds". Angew. Chem. Int. Ed. 52 (5): 1553–1555. doi:10.1002/anie.201208450. PMC 3563212. PMID 23239507.
- ^ Palmer, John (2006). "Hop Types". Retrieved March 29, 2011.
- ^ a b Kanta Sakamoto, Wil N. Konings (December 2003). "Beer spoilage bacteria and hop resistance". International Journal of Food Microbiology. 89 (2–3): 105–124. doi:10.1016/S0168-1605(03)00153-3. ISSN 0168-1605. PMID 14623377.
External links
editMedia related to chemical structures of alpha acids at Wikimedia Commons