Basic Brewery calculations, short version NOV 2011 Calculation of Specific Gravity (SGE) from %P of extract in wort at 20 oC: 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 oC) 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) α-acid in hops pellets: 5 % Brewsize: 7 hl 5 % α-acid in hops Kg hops per brew: Wanted B.U. x brewsize (hl) ---------------------------------------------------% Utilisation x % α-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 ER% EA% A%mas A%vol SGA SGE SGBeer means means means means means means means means Original extract in percent Plato Percent of Real Extract Percent of Apparent Extract Percent of Alcohol by mass Percent of Alcohol by Volume Specific Gravity of the Alcohol-containing distillate Specific Gravity of the Extract-containing reminiscence Specific Gravity of the Beer g/100g g/100g g/100g g/100g ml/100 ml g/ml over g/ml g/ml over g/ml g/ml over g/ml Pasteurisation: One Pasteurisation Unit (PU) is defined as the heat received by 60oC 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: