Problem definition
The production of beer is a complex and highly optimized biotechnological process with the objective of producing beer with a species- and brand-specific taste. The important quality characteristics of a beer are its colour, a stable froth and especially its typical flavour and taste. With regard to the taste the feature of bitterness has to be emphasized as it is an essential and very typical characteristics of beer. In order to transfer the alpha-acids of hop into the water-soluble and bitter iso-alpha acids of beer and thus obtain a bitter beer there are two possibilities: the classic isomerization or the ‚chemical’ isomerization. With the classic procedure the hop or the hop products are added during the wort boiling, with the chemical isomerization dosing capable solutions are added to the finished beer. In this case an inline measurement of the bitter substances can be used both as a control and regulation instrument.


Objectives and cooperation
The main objectives of the project are the development and validation of an inline measurement device for the determination of bitter substances in beer (Dausch Technologies, DT) as well as the establishment of a fast, selective and highly precise lab-reference measuring method for the determination of the bitter substances in beer by LC-MS (VLB). DT and VLB are supported by the ‚Reutlinger Steinbeis Transferzentrum für Prozesskontrolle und Datenanalyse‘ (STZ) in this process of model development and data analysis.

Realization
Considering the above mentioned objectives of the research project – the development of an inline measuring technique for bitter substances of beer, the sensitivity of the molecular-spectroscopic procedure, the usually bitter substance concentration in the beer (appr. 15-40 mg iso-alpha-acid per product litre), the cost and robustness factor – it can be stated that the absorption spectroscopy is a rather promising procedure for the inline measurement of bitter substances in beer. However, in contrast to the usually applied lab methods in the breweries the spectrum of a sample has to be measured over a broad wavelength range and the selectivity of the determination has to be increased by an appropriate data pre-processing.
Thus the following individual steps have to be carried out:

• Development of an inline measuring device for the determination of bitter substances in beer (BeerGuard) by means of absorption spectroscopy (DT)
• Development of a fast and highly specific reference analytics of bitter substances in beer by help of LC/MS (VLB)
• Development of an automated calibration module (lab module) for a faster calibration in industry (DT in cooperation with STZ)

Perspectives
By means of spectroscopic inline procedures in combination with intelligent calibration procedures, data analysis and a significant reference analytics even overlapping information can be separated. This opens up new perspectives for a future multicomponent analysis in the beer industry. This approach has already been validated during process analysis in various industry branches and for the first time could also be integrated into industrial processes in the beverages sector by the Dausch Technologies GmbH. Furthermore the approach of inline analytics developed by DT has proved itself in everyday industrial life over many years. The cooperation of Dausch Technologies, STZ and VLB guarantees that all the individual necessary technological aspects are taken into consideration for a successful realization of the project.