Module: Beer

Defined in:
lib/beer.rb

Overview

beer.rb

A collection of formulas that are useful during beer (and wine) making.

Author

Caleb Phillips <[email protected]>

Version

2007.05.20

License

“THE BEER-WARE LICENSE” (Revision 42): Caleb Phillips <[email protected]> wrote this file. As long as you retain this notice you can do whatever you want with this stuff. If we meet some day, and you think this stuff is worth it, you can buy me a beer in return.

Constant Summary collapse

E = 
2.71828183

Instance Method Summary collapse

Instance Method Details

#aau(w, a) ⇒ Object

Calculate the AAU (Alpha Acid Units) contributed by a given hops addition, using the alpha percentage (like 6.5) and the weight in ounces.



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# File 'lib/beer.rb', line 42

def aau(w,a)
  w*a
end

#abv(og, fg) ⇒ Object

determine alchohol by volume using the difference between original and final gravity from: www.brew-monkey.com/brewschool/introtoextract.php



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# File 'lib/beer.rb', line 127

def abv(og,fg)
  # convert to specific gravity if it looks
  # like we need it
  if (og > 2) or (fg > 2)
    og = g_to_sg(og)
    fg = g_to_sg(fg)
  end
  (og - fg)*131.25
end

#f_to_c(t) ⇒ Object

convert degrees fahrenheit to degrees celsius



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# File 'lib/beer.rb', line 83

def f_to_c(t)
  (t.to_f - 32)*(5.0/9.0)
end

#g_to_sg(g) ⇒ Object

convert gravity to specific gravity



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# File 'lib/beer.rb', line 88

def g_to_sg(g)
  1 + g*0.001
end

#ibu(w, a, t, og_pt) ⇒ Object

Find the IBU (international bitterness units) in a beer given:

w - an Array of weights (in ounces) a - an Array of alpha percentages (like 6.5) t - an Array of times (in minutes)

For the various hop additions. Also,

og_pt - the original gravity of the wort in the brew kettle (in gravity points, the 52 in 1.052 SG)



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# File 'lib/beer.rb', line 57

def ibu(w,a,t,og_pt)
  ret = 0
  W.each_index{ |i|
    ret += u(OG_pt,T[i])*aau(W[i],A[i])
  }
  ret = ret*75
  ret = ret/V_cb
  ret
end

#og_pt(og_cb, v_cb, v_pt) ⇒ Object

Determine original gravity of the wort in the brew kettle from the volume of the fermenter (v_cb), the gravity in the fermenter (og_cb) in gravity points (the 52 in 1.052 SG), and the volume of the pot (v_pt)



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# File 'lib/beer.rb', line 27

def og_pt(og_cb,v_cb,v_pt)
  (og_cb*v_cb)/v_pt
end

#pa_ucd(b, sg) ⇒ Object

determine potential alchohol using brix and specifig gravity of the original wort. This is the UC Davis “way” which accounts for some non-sugar fermentables. from: www.brsquared.org/wine/CalcInfo/HydSugAl.htm



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# File 'lib/beer.rb', line 120

def pa_ucd(b,sg)
  ((b-3)*sg)*0.59
end

#sg_correction_c(t) ⇒ Object

Temperature correction for specific gravity for hydrometers calibrated at 59F. Input is in degrees celsius. from: www.primetab.com/beer.c



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# File 'lib/beer.rb', line 71

def sg_correction_c(t)
  t = t.to_f
  if t < 3.98
    -0.000032692*t - 0.000740644  
  elsif t < 50
    -0.0008031922 - 0.0000473773*t + 0.000007231263*t*t - 0.00000003078278*t*t*t
  else
    -0.005431719 + 0.0001963596*t + 0.000002661056*t*t
  end
end

#sg_to_b(sg) ⇒ Object

convert specific gravity to degrees brix. degrees brix is the percentage of sugar. For instance 25 brix means 25 mg of 100 mg are sugar. See here for more info: en.wikipedia.org/wiki/Brix Formula from: www.brsquared.org/wine/CalcInfo/HydSugAl.htm



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# File 'lib/beer.rb', line 112

def sg_to_b(sg)
  220*(sg - 1) + 1.6
end

#sg_to_g(sg) ⇒ Object

convert specific gravity to gravity



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# File 'lib/beer.rb', line 93

def sg_to_g(sg)
  1000*(sg-1)
end

#sg_to_p(sg) ⇒ Object

convert specific gravity to plato from: www.primetab.com/beer.c plato is the percentage of sucrose in a water sucrose solution. It was developed by Kurt Balling and Fritz Plato. More information here: en.wikipedia.org/wiki/Plato_scale



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# File 'lib/beer.rb', line 103

def sg_to_p(sg)
  -676.67 + 1286.4*sg - 800.47*sg*sg + 190.74*sg*sg*sg
end

#u(og, t) ⇒ Object

Calculate utilization percentage for a hop addition given the time of the boil and the gravity in the brew kettle at the time of addition



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# File 'lib/beer.rb', line 34

def u(og,t)
  og = (og.to_f)/1000 + 1 if og > 2
  1.65*(0.000125**(og-1))*((1-(E**(-0.04*t)))/4.15)
end