What are hops? Bitterness Aroma & Flavor Hopping methods Forms Pellets, Plugs, Whole Hops Utilization and IBUs

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1 Slide Set 5

2 What are hops? Bitterness Aroma & Flavor Hopping methods Forms Pellets, Plugs, Whole Hops Utilization and IBUs

3 Hops They are the cone-shaped female reproductive structure of the hop plant (separate male and female plants) Climbing vines Grow in temperate regions (native to North America, Europe and Asia) The essential oils and resins are found at the base of the thin, papery outer leaves of the hops These oils and resins are responsible for the bitterness, aromas and flavors Natural preservative properties

4 Bitterness Sources The primary component of bitterness is derived from alpha acids found in hop resin The alpha acids are neither water soluble nor bitter until isomerized by boiling Longer boils isomerize more alpha acids In one hour, between 25% and 30% are isomerized Oxidized alpha acids (found in old or aged hops) Beta acids are not water soluble and do not isomerize in the boil but can oxidize, producing some bitterness Hop polyphenols are a minor influence

5 Aroma and Flavor Aromas come from essential oils found in hops Flavor is a combination of hop bitterness, resin (mouthfeel) and aroma Hop aromas and flavors are difficult to describe Palmer touches on aroma and flavor descriptions Key points: Essential oils are volatile, therefore flavoring hops are added at the end of the boil Style guides specify hop varieties that are style appropriate There are online hop substitution references (

6 Hopping Methods Mash added to the mash (not common) First Wort added to the boil kettle as the hot wort comes from the lauter tun. Bittering hops added to boil kettle for 45 to 90 min. Flavoring add to boil midway (less 30 min. left) Finishing add to boil with less than 15 min. left Steeping add at knockout when heat is removed Dry Hopping added at the end of fermentation to impart fresh hop aroma

7 Whole Hops, Plugs, and Pellets Whole the whole cone dried or fresh Advantages: easy to strain, best aroma, dry hopping Disadvantages: oxidizes faster, soaks up wort, clogs tubes. Plugs tightly compressed hops (typically in 0.5 oz. units) Advantages: retains freshness, behaves like whole hops in wort Disadvantages: difficult to break apart, soaks up wort Pellets shredded and compressed into small pellets Advantages: easy to weigh, best storability, small utilization increase due to shredding Disadvantages: turns to sludge in boil kettle, some loss of aroma, hard to contain for dry hopping

8 Hop Storage Store cold / refrigerated Airtight package Usually supplied in metallic foil Mylar bags Most plastics are permeable to O 2 If you have extra hops in open bags, you need to seal them well and store refrigerated Tightly fold the Mylar bag closed and seal with tape Place the sealed Mylar bag in a small Ziploc bag They should keep for several weeks You can purchase metallic foil Mylar bags from Amazon

9 Alpha Acid Units (AAU) AAU = weight in ounces percentage alpha acid This is a convenient way to describe the total bittering potential of a hop addition When making hop substitutions or to account for yearly variations in percentage alpha acid, a hop addition should have the same AAU. An addition of 1.5 oz. of 5% alpha acid hops imparts the same bitterness as 1 oz. of 7.5% alpha acid hops

10 Measuring Bitterness Quantified in International Bitterness Units (IBU) Equivalently referred as Bitterness Units (BU) There are analytical methods for measuring the bittering acids in a sample of beer and correlating that to the perceived bitterness White Labs will analyze a sample of your beer There are methods for estimating the bitterness of a beer recipe from boil times, hop weights, hop alpha acid content, and boil gravity

11 Estimating IBU IBU = 75 % Utilization Depends on Boil time Boil volume Wort gravity weight in oz. (% alpha acids) (% utilization) (final volume) Tops out around 30% for homebrew conditions Several models for calculating bitterness Tinseth model shown in Palmer s Table 5.5

12 Example At time 15 minutes Add 0.5 oz. Cascade hops 8.4% alpha acids Boil gravity Batch volume 5.5 gal. Read the utilization for 15 minute boil time and boil gravity from Palmer s Table 5.5 = IBU = = 7.2

13 Up Next Recipe Spreadsheet A spreadsheet that makes it easier to adjust and design beer recipes. Yeast and Fermentation How yeast work Yeast types (selections and substitutions) Improving fermentation