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The historical development of equations used to relate alcohol and real extract to apparent extract and original gravity, as well as ratios between the corrected Real (RDF) and Apparent Degrees of Fermentation (ADF), were examined in light of modern polynomial and non‐linear regression techniques. Comparisons were performed using an extensive data set of 532 brews obtained from commercial and pilot fermentations with statistical error analysis of these empirical relationships. New predictions of apparent extract were calculated as a function of alcohol and real extract analogous to the Improved Tabarie's formula. In addition, attempts at improving Balling's original equation model estimating original gravity from alcohol and real extract are detailed and discussed. The statistical analyses of relationships between Aw/w (alcohol by weight) and functions of OE (Original Extract), AE (Apparent Extract) and RE (Real Extract) as well as ratios between the corrected Real and Apparent Degrees of Fermentation (RDF/ADF) are reported. It is expected that this paper will be useful for brewers to more accurately estimate Aw/w and real extract values.

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The American Society of Brewing Chemists collaboratively tested a gas chromatographic method for determination of ethanol in beer. Ten laboratories collaborated in a comparison of the ASBC reference method for alcohol by distillation with the GC method. The latter was shown to be at least as precise as the former, it is more rapid, and it can be used for in-line or process monitoring. The method has been adopted official first action.