This method describes how to determine the extract content of liquid adjuncts by means of relative density measurement.
Adjuncts in liquid form which are soluble in water
Determination of relative density sL 20/20 °C with a pycnometer or other suitable density measurement device
Determination/calculation of the apparent extract content from the SGA20/20 or the density of a liquid
wort, beer, beer-based beverage, NAB, beverage
Determine the SGA20/20 obtained from pycnometry or the density measured with a precision hydrometer or another device for measuring the density. Using the value from the SGA20/20 measurement or the density from the sugar, alcohol, original gravity and correction table according to GOLDINER/KLEMANN, BLOCK, KÄMPF or a polynomial, determine the apparent extract content of the sample.
Determination of the original gravity, alcohol and extract content using an oscillating U-tube density measuring device and an alcohol sensor in beer or beer-based beverages
Aside from the density, the alcohol concentration is also directly measured with an alcohol sensor. This is carried out using catalytic combustion. In a measured stream of air, alcohol vapor rises countercurrent to the beer flowing downwards. The alcohol vapor is oxidized at the sensor and the resultant heat is measured by means of a resistive circuit. This correlates with the concentration of alcohol in the beer. According to Tabarié’s equation, the relationship between the specific gravity of beer, its alcohol content and real extract content can be calculated as follows:
\(\rho_{\text{beer}} = \rho_{\text{alcohol}} \space + \space \rho_{E_R} \space – \space \rho_{\text{water}}\)
\(\text{SG}_{\text{A20/20 beer}} = \text{SG}_{\text{A20/20 alcohol}} \space + \space \text{SG}_{\text{A20/20}}E_R \space – \space \text{SG}_{\text{A20/20 water}}\)
\(\text{SG}_{\text{A20/20 alcohol}} = 1.000\)
Determination/calculation of original gravity, alcohol and real extract content after distillation of beer, beer-based beverages or beverages.
Beer, beer-based beverages, beverages
After distillation of the sample, the original gravity, alcohol and real extract content of the beer in beer-based beverages or other beverages can be determined from the densities of the distillate and residue.
Determination of original gravity, alcohol and extract content by measuring the density using a flexural oscillator and the sonic velocity in beer or beer-based beverages.
wort, beer, beer-based beverages
The speed of sound in a liquid is a function of the alcohol and extract content and the temperature. Over a travel distance of 5 mm defined by two parallel surfaces, the speed of sound propagates as a function of the concentration of the dissolved substances. The speed of sound is defined by the quotient of the running distance s and the measured time t [1]. The density of the test liquid is a function of the concentrations of alcohol and extract content. Therefore, the actual extract, alcohol and original wort content can be determined from the speed of sound (ν) and the density.
beer, beer-based beverages, beverages
The refraction of a light beam as it passes from an optically less dense (sample liquid) to an optically denser medium (prism) is a function of concentration (alcohol/extract), temperature and wavelength. The density of the test liquid is a function of the concentrations of alcohol and extract content. Therefore, from the refractive index (or alternatively the refractive index nD20 and the density or the SGA20/20, the real extract), the alcohol and original gravity can be determined from nomograms or using regression equations.