Comparison of the foam behavior of different types of degassed beer
Analysis of the foamability, foam stability and foam structure of beer samples
For a long time food-chemical analyses and quality tests for beer were focused primarily on the biological stability of this popular drink. However, the emphasis in recent years has changed: the brewing industry has developed high and reliable standards with regard to the shelf life of beer, while research and quality assurance focuses increasingly on the aspect of enjoyment . In this connection priority is now also being given to topics such as the formation, consistency and stability of beer foam.
Beer foam forms through the combination of the natural surfactants it contains and the carbon dioxide (CO2) that forms as a reaction product during the brewing process. The latter is not added; the only time additional CO2 is used is during tapping in order to generate the necessary pressure. This study presents a possibility for analyzing the impact of foam-forming substances on foamability and foam stability independently of the CO2 content. For this purpose the foam height and foam structure of the beer types Pils, clear wheat beer and Kölsch, a popular German local specialty beer, were measured with the CO2 having been removed in advance of the measurement. The analysis showed that the behavior of the foam of the beer samples that had been standardized for the measurement deviated greatly from the properties of tapped beers. In particular the behavior of Kölsch beer that only foams a little when tapped was the cause of much surprise during our study.