VIEW ARTICLE    DOI: 10.1094/ASBCJ-49-0078

Experiences with a New Foam Stability Analyzer, System Carlsberg. Lars Hallgren, Ib Rosendal, and Jan Nørager Rasmussen, Carlsberg A/S, 100 Vesterfaelledvej, DK-1799 Copenhagen V, Denmark. J. Am. Soc. Brew. Chem. 49:0078, 1991.

Two new versions of the Carlsberg foam stability analyzer have been developed. One is fully automated and is based on video camera readings; the other is manual and is based on visual estimation. The evaluation of foam quality is based on measurements of total foam volume and foam stability. Head retention is measured as changes in the beer volume during drainage of the foam. In the automated apparatus, sampling is performed directly from the original bottle or can, and measurements can be taken at 4-25° C. The automated apparatus has a capacity of 18 beer samples and can test one beer every 10 min. Measurements show that foam drainage half-life correlates negatively with temperature, whereas foam volume correlates positively. Foam volume and foam drainage half-life correlate positively with the CO₂ content within the same brand of beer, but the variation found in foam drainage half-lives among brands cannot be explained by variations in CO₂ content. Good correlations were found between results from the two new apparatuses and from an earlier version of the apparatus, although the coefficient of variation improved for the new automated and the new manual apparatus (1.8% and 2.2%, respectively), compared with the old equipment (3.8%).

Keywords: Foam stability analysis, Head retention of beer, Foam drainage half-life, Electronic measurements, Automated sampling.