Search: oscillating U-tube

Determining the density with a digital density measuring device is performed by the electric excitation of a measurement cell (oscillating U-tube) filled with the solution to be analyzed. As the solution increases in density (corresponding to an increase in mass at the same volume in the measurement cell), this has an effect on the oscillation period (resonance frequency) in the measurement cell. The density can then be calculated from the oscillation period and from this value, the other quantities, e.g., extract content, can be extrapolated [1, 2, 3]. 

Determine the SG_A20/20 obtained from pycnometry or the density measured with a precision hydrometer or another device for measuring the density. Using the value from the SG_A20/20 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.

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:

\(\rho_{\text{beer}} = \rho_{\text{alcohol}} \space + \space \rho_{E_R} \space – \space \rho_{\text{water}}\)

\(\text{SG}_{\text{A20/20 beer}} = \text{SG}_{\text{A20/20 alcohol}} \space + \space \text{SG}_{\text{A20/20}}E_R \space – \space \text{SG}_{\text{A20/20 water}}\)

\(\text{SG}_{\text{A20/20 alcohol}} = 1.000\)

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.

Solids contained in the wort are separated by filtration at a temperature of approx. 85 °C and measured by weighing.

The hot break material (trub) and any hop particles which may be present in the wort, must first be removed. After the wort has been cooled to 2 °C, it is filtered through a glass fiber filter. The residue remaining on the filter is dried and then weighed.

Cold break material or cold trub refers to all material that settles out in the process of chilling wort after separation of the hot trub or hot break material. Cold trub can be filtered out of the wort and primarily consists of proteins (48–57 %), tannins (11–26 %) and carbohydrates (20–36 %). The amount of cold break material in wort depends on the quality and composition of the raw materials, brewhouse equipment and wort handling. In academic and professional circles, opinions regarding the significance of cold break material for downstream processes and for the quality of the finished beer are strongly divided [1, 2, 5]. Under certain circumstances, the quantity of cold break material in wort may exceed 250 mg/l, especially where accelerated fermentation is practiced. Ultimately, this can detract from the flavor of the finished beer [3]. Breweries, where removal of the cold break material has been practiced successfully, determine the quantity of cold break in their pitching wort at regular intervals, in order to evaluate the efficacy of their separation equipment.