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:
\(\rho_{\text{beer}} = \rho_{\text{alcohol}} \space + \space \rho_{E_R} \space – \space \rho_{\text{water}}\)
\(\text{SG}_{\text{A20/20 beer}} = \text{SG}_{\text{A20/20 alcohol}} \space + \space \text{SG}_{\text{A20/20}}E_R \space – \space \text{SG}_{\text{A20/20 water}}\)
\(\text{SG}_{\text{A20/20 alcohol}} = 1.000\)
This method describes the conditions under which sensory analysis should be carried out.
beer, beer-based beverages, non-alcoholic beverages, mineral water
One of the basic prerequisites for properly conducting sensory analysis is choosing an appropriate number of samples and presenting them to tasters in the relevant sequence.
beer
As with the DLG score sheet, the individual criteria are assessed on a five-point scale. The criteria judged in the evaluation represent a combination of factors pertaining to the assessment of quality (purity of aroma, purity of flavor, quality of bitterness, overall quality) and intensity (bitterness, hop aroma, fullness, liveliness). It is important to note that with reference to fullness, an optimum score is 3 or 4.
A known quantity of an internal standard (n-propanol) is added to the sample, if necessary after dilution.
The sample is equilibrated at a certain temperature in a headspace vial and part of the headspace is injected into a gas chromatograph.
The ethanol contained is separated on a polar gas chromatography column and detected with a flame ionization detector (FID).
The ethanol concentration in % vol. is calculated from the ratio of the area of the ethanol peak to the area of the internal standard (n-propanol) with the ratios of the same peaks determined when analyzing standards with known ethanol concentrations.
Determination of sorbitol by ion chromatography and pulsed amperometric detection
This method is suitable for fruit juices and other non-alcoholic beverages.
The sugar alcohols are separated using a strongly alkaline eluent and ion exchange column and detected and quantified electrochemically using a pulsed amperometric detector (PAD).
By applying a potential, the ions are oxidized at a gold electrode and induce a measurable charge. To prevent the electrode from being occupied in a very short time, the potential is then reversed to reduce and release the ions from the electrode.
Quantitative detection of harmful osmophilic and osmotolerant yeasts, moulds and bacteria in non-alcoholic beverage raw material samples.
Raw material samples (e.g. fruit juice concentrates, sugar syrup, etc.) in the non-alcoholic beverage section.
Detection of harmful osmophilic and osmotolerant yeasts, moulds and bacteria using the pour-plate method.