Relationship of Proteinase Activity, Foam Proteins, and Head Retention in Unpasteurized Beer

摘要

Head retention, proteinase activity, and protein content in unpasteurized beer stored at different temperatures for different storage times were tested. Analysis of variance indicated that treatment (pasteurization), storage time, storage temperature, and associated interactions all had highly significant effects on the level of proteinase activity, head retention, and protein content. The change in beer proteins during storage and the relationship between proteinase A and foam proteins were also studied. The results of sodium dodecyl sulfate-polyacrylamide gel electro-phoresis indicated that lipid transfer protein 1 was degraded and this foam-active protein was a major substrate of proteinase A. Degradation of lipid transfer protein 1 is a major factor that causes a decrease in beer foam stability.