Determination of the original gravity, alcohol and extract content in beer or beer-based beverages using a thermoanalytical method
wort, beer, beer-based beverages
Rather than utilizing the classic method for analyzing beer by means of density measurement and/or alcohol determination, this device employs thermoanalytical analysis techniques. With two thermoanalytical measuring cells, the beer sample is heated to 40 °C and 65 °C, and the specific heat capacity is determined. Algorithms are used to assign the results to the concentration of the various ingredients. In this way, alcohol content, apparent and real extract, and original gravity are calculated.
Determination of iso α-acids and α-acids in beer, beer-based beverages and wort
This method is not suitable for beer, beer-based beverages or wort, which contain saccharin, p-hydroxybenzoic acid ester, salicylic acid or sorbic acid.
These bitter substances are extracted from the acidified sample using iso-octane. Certain disruptive substances are eliminated through washing the extract with acidified methanol. The concentration iso-α-acids as well as α-acids is determined by measuring the absorbance in alkaline methanol at 255 nm and 360 nm.
Determination of the free, volatile fatty acids in beer and wort
The method is suitable for wort and beer of any original gravity and alcohol content.
Volatile substances in beer are concentrated through distillation and the distillate is extracted using dichloromethane. The solvent phase is concentrated in the rotary vacuum evaporator and subsequently analyzed using a gas chromatograph. The linearity of the detector and the determination of the concentrations of analytes in the sample is achieved by using multiple concentration levels within the relevant range and through evaluation of the relative area under the peaks.
This method describes how to determine the foam stability by means of the Ross and Clark method.
beer and beer-based beverages
CO2 is introduced into the beer so that a specific volume of foam is produced. The mean retention time of the bubbles in the foam serves as a measure for the foam stability, which is calculated as the relationship between the time required for the foam to collapse and the logarithm of the relationship between the volume of the collapsed foam and the foam still present [1–3].
This method is frequently applied in instances when the influence of carbon dioxide content on foam formation in the beer is to be eliminated.
Determination of the foam stability
Beer and beer-based beverages
In determining the foam stability with the Steinfurth Foamtester SFT, the time required for the foam to collapse in a graduated cylinder is measured.
The pressurization is carried out in such a way that the container does not require degassing. The attempered beer is injected into the measuring cylinder through a nozzle, and in the process, foam is formed. The foam stability is determined by several optical sensors detecting the time necessary for the beer/foam interface to pass by them. The precise metering of a predetermined quantity of beer, the entire process of executing the analysis and displaying the results as well as cleaning and conditioning of the measurement cylinder are performed automatically.
Determination of the capacity for foam to cling to the side of a glass
Beer and beer-based beverages
The measurement with the NIBEM Cling Meter (fig. 1) is normally performed immediately after the NIBEM foam stability measurement and serves to provide additional information on foam quality.
After the preset timer has expired, a scan head is introduced into the Haffmans standard glass while the glass is rotated slowly at a fixed level, in order to ensure that the foam has collapsed a minimum of 48 mm. An LED on the back of the scan head emits light. The diffused light, which reflects off of the inside of the glass, is read by a sensor and recorded.