Style (Recipe) Design History Calculation Info
Alcohol (% abv)
Alcoholic content (as % alcohol by volume) is calculated from temperature corrected Brix or specific gravity (SG) readings, measured by refractometer and hydrometer. The method used is detailed under method 2 under "Potential Alcohol" here.
Titratable Acidity (TA)
Titratable acidity is calculated as tartaric acid (as is practically the international convention) using an NaOH titration and a pH meter to the endpoint pH 8.2. (This follows the method described by the U.S. Association of Official Analytical Chemists. Samples are typically undiluted and between 20 and 50 ml.)
pH
pH is given to two decimal places and is calculated (with temperature compensation) with a meter accuracy of +/- 0.01 and a buffer solution accuracy of +/- 0.01, resulting in an overall pH accuracy of +/- 0.014.
(Where pH is given to one decimal place, meter accuracy is +/- 0.2 (resolution 0.01) and overall pH accuracy is +/- 0.200.
Frequent calibrations are made with pH 4.01 and 7.01/6.88 buffers.
Residual Sugar (r.s.)
Residual sugar is measured by either copper reduction method or back calculated from Brix/SG readings.
(Brix values are based on SG values using the formula: Brix = ((SG-1)*220)+1.6)
Free SO2 (FSO2)
Free SO2 is calculated using the Ripper method. Value adjustments may be made. Control solutions are used for calibration.
Tasting
All comparative tastings are conducted using standard ISO tasting glasses. Most tastings are verified by both experienced and inexperienced tasters other than the winemaker. Such tastings are almost always conducted blind.
