Science Fair Project Encyclopedia
International Bitterness Units scale
The hoppy character of beer is measured by the International Bitterness Units scale, or IBU scale for short. An IBU is one part per million of isohumulone. The higher number, the greater the bitterness.
- Belgian Lambics: 11-23
- Blonde ale: 15-30
- Kölsch: 18-25
- Märzen/Oktoberfest: 18-25
- Ordinary English bitter: 20-35
- Porter: 20-40
- Brown ale: 15-25, with North American styles higher, 25-45
- Bohemian-style Pilsener: 30-45
- India Pale Ale: 40 or higher
- An Irish stout like Guinness: 45-60
- Stone Ruination IPA: 100+
One formula craft brewers use to calculate IBU is
hop weight × AA% × utilization × volume × 1.34
- hop weight refers to the weight of the hops used in ounces.
- AA% refers to the alpha acid percentage, which is influenced by many factors, including method of cultivation, species, and time of year. Hops are often sold labeled with this percentage.
- utilization is the percentage of Alpha acid that is actually used during the boiling process.
- volume means the volume of the wort in gallons.
- the constant (1.34) adjusts the measurement to account for the use of U.S. customary units.
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details