Comparison of foam analysis methods and the impact of beer components on foam stability

In this study, three widely used Mitteleuropäische Brautechnische Analysenkommission (MEBAK) foam analysis methods were compared, and their relationship to the standard analyses of foam stability was determined. In total, over 40 beers were analyzed using the standard MEBAK beer analysis and foam stability methods (NIBEM, Ross and Clark, and Steinfurth Foam Stability Tester). The results obtained were compared by linear regression analysis. In contrast to earlier investigations, all beers assessed were brewed according to the German Purity Law. The investigation showed that the three foam analysis methods were comparable and had high reproducibility. An interesting observation was that the methods measure foam stability somewhat differently, with different beer components having variable contributions to foam stability in the individual foam analysis methods. Further, we found that the results of the commonly used standard MEBAK analysis for beer quality were not suitable for prediction of beer foam stability. Although the influence of β-glucan on foam stability is controversial in the literature, β-glucan content showed a positive influence on the foam stability of all the foam-measuring methods used in this study. A likely explanation for the contribution of β-glucan to foam stability in our study could be that, in many previous investigations, beer was produced with the assistance of glucanases to lower the β-glucan content and its molecular mass size. Therefore, our beers have relatively higher β-glucan contents and sizes, which may explain our contradictory results. In addition, polyphenol content was also a significant predictor of foam stability in our multilinear regression models.