Relationship between Matrix Foaming Potential, Beer Composition, and Foam Stability

Abstract

Qualitative research with Czech beer customers was the starting point for this investigation of beer foam quality. We observed that customers start to pay attention to foam no earlier than when “bald patches” begin to appear on the surface of the beer. This foam stability trait was observed toward the end of foam collapse. In contrast, foam stability measured by common quality control methods such as NIBEM conventionally measure foam stability during the first stages of foam collapse. To evaluate the rate of appearance of bald patches on beer, we have developed a method that predicts foam stability during the later stages of collapse, in order to reflect Czech customers' expectations for foam quality. This alternative foam analysis method directly produces foam from degassed beer and evaluates its quality to determine the matrix foaming potential measurement. Foam stability is a compromise between foam-positive and -negative beer components. Traditionally accepted foam components such as foam-positive proteins and hop iso-α-acids describe the quality of foam only to a limited extent, particularly because iso-α-acids content is tightly controlled within brands. Our foam analysis technique indicates that beer is essentially saturated with more than sufficient levels of foam-positive components to satisfy the requirements for foam generation and stability. Consequently, we demonstrate that foam-negative components are the actual problem that needs to be solved to improve foam quality with respect to the appearance of bald patches on the surface of beer.