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Brewing Calculations Short Vers. NOV 2011 Agk

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The document discusses various formulas for brewery calculations including specific gravity, brewhouse yield, mash thickness, original extract, evaporation, hop dosing, degree of fermentation, and alcohol content.

Formulas discussed include calculations for specific gravity, brewhouse yield, mash thickness, original extract in the kettle, evaporation in the kettle, and hop dosing.

Key parameters used in the calculations include original extract percentage, specific gravity, volume, end volume, end specific gravity, brew size, alpha acid content of hops, utilization percentage, and dilution.

Basic Brewery calculations, short version NOV 2011

Calculation of Specific Gravity (SGE) from %P of extract in wort at 20


o
C:
The extract content (kg extract / hl wort at 20 C) in the wort will be:

kg Extract / hl cold wort = OE%P * SG

This however requires knowledge of the specific gravity (SG)

For quick & dirty calculation only:

SG = 1 + 0.004 * OE%P

This hipshot formula is better for weaker wort than for stronger.

Calculation of Brewhouse yield:

Brewhouse yield =
Amount of extract in finished wort / Amount of extract from brewing materials:

Large breweries expect yield > 98 %, and micro breweries may be > 85 %.

Calculation of mash thickness:

The proportion of brewing water to brewing materials is interesting as it indicates the
thickness of mash:
Water / Materials = 652.5 / 225 = 2.9 liter water / kg materials

Normal values for this figure for lautertun process will be in the range: 2.8 3.5
depending on the actual mashing recipe.


Volume of mash

As a rule of thumb 1 kg malt grits take up 0.8 l space in the mash.
Total mash volume will then be (using numbers from calculation of first wort extract):

652.5 + 0.8 x 225 = 832.5 liter (at 20
o
C)



Calculation of OE in kettle full before boiling:

To calculate the OE in the wort kettle before boil, one must know the end gravity (SG),
end volume (after evaporation) and the end SG:

Beg SG = OE = End Volume * End SG / Beg Volume



Calculation of evaporation in wort kettle:

End volume (after boil) = 10 hls (before boil) * 36 / 40 = 9 hls.
In other words: 1hls has evaporated during the boil.


Calculation of hop dosing, simplified way only.

Assumptions:
Yield 50% (brewery specific)

-acid in hops pellets: 5 %

Brewsize: 7 hl

5 % -acid in hops


Wanted B.U. x brewsize (hl)
Kg hops per brew: ----------------------------------------------------
% Utilisation x % -acid in hops used


Dilution Formula

Dilution/gravity calculations including evaporation calculations in the brewhouse
are based on a simple formula using volumes in hls and Specific Gravity (SG):

Beg Volume * Beg SG=End Volume * End SG

(The SG numbers are SG Points, i.e. 1.060 SG = 60 gravity pts, 1.045 = 45 SG pts.)

By re-arranging this formula, we find:

Beg Volume=End Volume * End SG / Beg SG

Beg SG=End Volume * End SG / Beg Volume

End SG=Beg Volume * Beg SG / End Volume

End Volume=Beg Volume * Beg SG / End SG


Degree of fermentation:

The apparent degree of fermentation (ADF) is the value, you read using the
saccharometer. The ADF is approx. = 1.24 * real degree of fermentation (RDF).



Craft formula: Useful for breweries with limited laboratory instrumentation.

Alcohol calculation from OE: The Craft Formula
In small breweries the instrumentation in production and in the laboratory may only allow
for measurement of gravities.
A hydrometer (saccharometer) may be used to measure the strength of the wort before
fermentation (OE%P) and the apparent extract (EA%) in the beer during processing and
in the final beer. As long as no sugar, syrup or water is added to the beer in the tanks,
the following new formula will calculate the Percent of Alcohol by Volume (A%vol):

A%vol=(OE%P - EA%) / (2.048 - 0.0126*OE%P) ( The Craft Formula)

Abbreviations used above


OE%P means Original extract in percent Plato g/100g
ER% means Percent of Real Extract g/100g
EA% means Percent of Apparent Extract g/100g
A%mas means Percent of Alcohol by mass g/100g
A%vol means Percent of Alcohol by Volume ml/100 ml
SGA means Specific Gravity of the Alcohol-containing distillate g/ml over g/ml
SGE means Specific Gravity of the Extract-containing reminiscence g/ml over g/ml
SGBeer means Specific Gravity of the Beer g/ml over g/ml


Pasteurisation:

One Pasteurisation Unit (PU) is defined as the heat received by 60
o
C in 1 minute. The
precise connection is defined as:

PU = time * 1.393
(Temp. 60)


Time is measured in seconds/60
Temperature is measured in C.
In stead of using this formula, you may simply use this diagramme:

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