Interpolation formulas for Balling's alcohol factors

The article deals with the interpolation of the Balling alcohol factors, given at isolated points in 1% (m/m) increments ranging from 1 to 30% in the Hrach table published in 1927. Interpolation was necessery for the calculation of real (RDF) or apparent (ADF) degree of attenuation, according to which optimal barley varieties were selected for beer production. Analytica EBC initially preferred ADF, although it also reported on the RDF used by ASBC. According to ASBC, the Balling RDF is multiplied by a correction factor or calculated using a modified calculation formula. Both ways gave the same results and increased Balling RDF values by 1-2% m/m. Refractometry with a pocket digital refractometer set to degrees Bx allows beer analysis from a minimum sample volume. During fermentation of a sugar substrate with a constant original extract, the apparent extract is a linear function of the sample refraction.