Class: BeerRecipe::Formula

Inherits:
Object
  • Object
show all
Defined in:
lib/beer_recipe/formula.rb

Instance Method Summary collapse

Instance Method Details

#calories(serving_size, abv, og, fg) ⇒ Object 



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# File 'lib/beer_recipe/formula.rb', line 41

def calories(serving_size, abv, og, fg)
  r = real_extract(og, fg)
  ( 6.9 * ( 0.79 * ( abv / fg ) ) + 4 * ( r - 0.1 ) ) * fg * ( serving_size / 100 )
end

#ebc_to_srm(ebc) ⇒ Object 



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# File 'lib/beer_recipe/formula.rb', line 3

def ebc_to_srm(ebc)
  ebc / 1.97
end

#mcu(amount, srm, volume) ⇒ Object 



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# File 'lib/beer_recipe/formula.rb', line 28

def mcu(amount, srm, volume)
  # MCU = (weight kg * lovibond * 2.205) / (volume * 0.264)
  (amount * srm * 2.205) / (volume * 0.264)
end

#mcu_to_srm(mcu) ⇒ Object 



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# File 'lib/beer_recipe/formula.rb', line 11

def mcu_to_srm(mcu)
  # SRM color = 1.4922 * (MCU ** 0.6859)
  srm = 1.4922 * (mcu ** 0.6859)
  if srm > 8
    srm
  else
    mcu
  end
end

#mgl_added_alpha_acids(batch_size, alpha, amount) ⇒ Object 



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# File 'lib/beer_recipe/formula.rb', line 67

def mgl_added_alpha_acids(batch_size, alpha, amount)
  (alpha * amount) / batch_size
end

#real_extract(og, fg) ⇒ Object 



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# File 'lib/beer_recipe/formula.rb', line 46

def real_extract(og, fg)
  p = (-205.35 * (og ** 2)) + (668.72 * og) - 463.37
  q = (-205.35 * (fg ** 2)) + (668.72 * fg) - 463.37
  (0.1808 * p) + (0.8192 * q)
end

#sg_to_abv(og, fg) ⇒ Object 



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# File 'lib/beer_recipe/formula.rb', line 33

def sg_to_abv(og, fg)
  if og > 0 && fg > 0
    ( (76.08 * (og - fg) / (1.775 - og) ) * (fg / 0.794) )
  else
    0
  end
end

#srm_to_ebc(srm) ⇒ Object 



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# File 'lib/beer_recipe/formula.rb', line 7

def srm_to_ebc(srm)
  srm * 1.97
end

#srm_to_rgb(srm) ⇒ Object 



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# File 'lib/beer_recipe/formula.rb', line 21

def srm_to_rgb(srm)
  r = [255, [0, 255 * (0.975 ** srm)].max].min
  g = [255, [0, 245 * (0.88  ** srm)].max].min
  b = [255, [0, 220 * (0.7   ** srm)].max].min
  [r, g, b]
end

#tinseth(batch_size, boil_time, og, alpha, amount) ⇒ Object 



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# File 'lib/beer_recipe/formula.rb', line 52

def tinseth(batch_size, boil_time, og, alpha, amount)
  # Bigness factor = 1.65 * 0.000125^(wort gravity - 1)
  # Boil Time factor = 1 - e^(-0.04 * time in mins) / 4.15
  # Decimal Alpha Acid Utilization = Bigness Factor * Boil Time Factor
  # mg/l of added alpha acids = (decimal AA rating * grams hops * 1000) / liters of wort
  # IBUs = decimal alpha acid utilization * mg/l of added alpha acids
  decimal_aa_rating = alpha / 100
  bigness_factor = 1.65 * ( 0.000125 ** (og - 1) )
  boil_time_factor = (1 - Math::E ** ( -0.04 * boil_time ) ) / 4.15
  alpha_acid_utilization = bigness_factor * boil_time_factor
  added_alpha_acids = (decimal_aa_rating * amount * 1000) / batch_size
  ibus = alpha_acid_utilization * added_alpha_acids
  return ibus
end