Abstract 043
The Relationship of Beer High Molecular Weight Protein and Foam
Tech. Quart. Master Brew. Assoc. Am. 26: 139-146, 1989
K.J. Siebert and E.J. Knudson
The Coomassie blue dye binding assay has previously been used to determine high molecular weight protein (HMWP) in beer. The proteins measured with this method are generally considered to be those over 5,000 Daltons. We have found that Coomassie blue dye binding results correlate strongly with beer foam determined by the Rudin head retention value (HRV) and NIBEM methods. When the nature of the various proteins in malt and the specificity of the dye binding response for polypeptides rich in particular amino acids were considered, two things became apparent: It is clear that the dye binding results under-represent hordein, the major protein in malt and beer, and emphasize proteins of the type which Asano and Hashimoto found to be most important for beer foam. As a result, the dye binding assay gives a much better estimate of the foam-active protein than would a non-biased measurement of protein greater than a particular molecular weight. The Coomassie blue assay was used to study processing factors which influence the level of HMWP in the beer. It was determined that with an essentially constant process, the amount of HMWP in beer could be predicted from the percentage of malt in the mash bill and the beer O.G. Approaches to increase the levels of HMWP in beer are discussed.
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