Brew Day Presentation Calculating Hop Bitterness

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Brew Day PresentationCalculating Hop Bitterness
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Measuring Hop Bitterness

• Homebrew Bittering Units (HBUs)HBUs Hop Wt. in
  (ounces)Alpha Acid PercentFor example, if you
  use 2.5 ounces of Cascade Hops with an alpha acid
  of 6.5 then the HBUs 2.56.5 16.25 homebrew
  units

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Measuring Hop Bitterness

• International Bittering Units (IBUs)IBUs
  Milligrams of iso-alpha acids in each liter of
  beerProfessionally, IBUs are measured with a
  spectrophotometer

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Hop Utilization

• The efficiency of the alpha acid bittering
  process is called the hop utilization.
  Basically, the hop utilization is the amount of
  iso-alpha acids in the finished beer relative to
  the alpha acids added during the brewing
  processAlpha Acid Utilization
  IBUs Alpha Acids Added in mg per
  liter
• or IBUs Alpha Acid UtilizationAlpha Acids
  Added(mg/l)

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Hop Utilization Factors

• amount of hops added to the brew kettle
• The length of the boil
• Gravity of the wort during boiling
• Hop rate i.e. alpha acids per liter of wort
• Type of hop, i.e. whole or pellets
• Filtering or using a hop bag
• Boil Temperature (altitude where you brew)

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Estimating IBUs

• Four methods to estimate IBUs
• Jackie RagerCalulating Hop Bitterness in Beer,
  Zymurgy Special 1990 (vol. 13, no. 4)
• Mark GaretzUsing Hops, The Complete Guide to
  Hops for the Craft Brewer, Hop Tech 1994
• Ray DanielsDesigning Great Beers, Brewers
  Publications 1996
• Glen Tinsethwww.realbeer.com/hops

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Estimating IBUsRager Formula

• The Rager Formula for estimating IBUs IBU U
  Woz A 7462
• Vgal (1 GA)
• Where
• GA (GB 1.050)/.2

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Rager Formula Variables

• GB Gravity of boiling wort at end of boil
• GA Gravity adjustment
• Woz Hop weight in ounces
• Vgal Volume of beer fermented in gallons
• U Boil utilization percent
• A Hop alpha acid percent

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Example 1

• Estimate the IBUs if you boil 1.5 ounces of
  Willamette hops for 45 minutes. The hops have an
  alpha acid of 6.5 and they are whole hops.
  Also, the hops are boiled in 3 gallons of wort
  and you plan to add 2 gallons of water after the
  boil to make 5 gallons of beer with an OG of
  1.040. Use the following formulas(a) Rager(b)
  Daniels(c) Garetz (d) Tinseth

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Example 1 (a) Solution

• Determine the gravity of the boiling wort GB
  (OG-1)(Ferment Vol)/(Boil Vol) 1
  (1.040 -1)5/3 1 1.066666667
• Determine gravity adjustment GA (GB
  1.050)/.2 (1.066666667 1.050)/.2
  .083333333

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Example 1(a) Solution cont

• Determine the IBUs IBUs .269 1.5 .065
  7462 5 (1 .08333333) 36.13

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Estimating IBUsDaniels Formula

• The formula from Ray Daniels to estimate IBUs is
  similar to Rager except for the conversion factor
  and the U values IBU U Woz A 7489
• Vgal (1 GA)
• Where
• GA (GB 1.050)/.2

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Example 1 (b) Solution

• Determine the gravity of the boiling wort GB
  (OG-1)(Ferment Vol)/(Boil Vol) 1
  (1.040 -1)5/3 1 1.066666667
• Determine gravity adjustment GA (GB
  1.050)/.2 (1.066666667 1.050)/.2
  .083333333

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Example 1 (b) Solution cont

• Determine the IBUs IBUs .22 1.5 .065
  7489 5 (1 .083333333) 29.66

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Estimating IBUsGaretz Formula

• Mark Garetzs formula for estimating IBUs is also
  similar to Rager, except Garetz adds a
  temperature factor and a hopping rate factor and
  the U values are different.The Garetz Formula
  for estimating IBUs IBU U Woz A
  7490
• Vgal (1 GA) TF HF

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Estimating IBUsGaretz Formula

• Where
• GA (GB 1.050)/.2
• TF ((Elevation in feet/550)0.02) 1CF
  (Ferment Vol)/(Boil Vol)HF (CFIBU/260) 1

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Estimating IBUs Tinseth Formula

• Glenn Tinseths formula for calculating IBUs uses
  a Bigness factor and a Boil time factor to
  determine the overall utilization. Here is the
  formulaIBU U Woz A 7490
• Vgal

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Estimating IBUs Tinseth Formula

• Where U represents total utilization and is
  defined as
• U Bigness factor Boil time factor
• Bigness factor 1.65.000125(average wort boil
  gravity-1)
• Boil Time factor 1 e(-.04time in
  mins) 4.15