VIEW ARTICLE    DOI: 10.1094/ASBCJ-64-0033

Relationship of Proteinase Activity, Foam Proteins, and Head Retention in Unpasteurized Beer. Guo-Qing He (1), and Zhao-Yue Wang, Department of Biosystems Engineering and Food Sciences, Zhejiang University, Hangzhou 310029, People’s Republic of China; Zhong-Shan Liu, China Lion Brewery Group, Wenzhou 325000, People’s Republic of China; Qi-He Chen and Hui Ruan, Department of Biosystems Engineering and Food Sciences, Zhejiang University, Hangzhou 310029, People’s Republic of China; and Paul B. Schwarz, Department of Plant Sciences, North Dakota State University, Fargo, ND 58105. (1) Corresponding author: Phone: +86.0571.86971166; Fax: +86.0571.86971166; E-mail: <gqhe@zju.edu.cn> J. Am. Soc. Brew. Chem. 64(1):33-38, 2006. Accepted April 10, 2005.

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 electro­phoresis indicated that lipid transfer protein1 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. Keywords: Foam stability, Lipid transfer protein 1, Pasteurization, Pro­tein

La retención superficial, actividad proteinasa, y contenido proteínico en cervezas no pasteurizadas almacenadas a diversas temperaturas por diversos tiempos de almacenaje fueron examinadas. El análisis de variación indicó que el tratamiento (pasteurización), tiempo de almacenaje, temperatura de almacenaje, y todas las interacciones aso­ciadas tuvieron efectos significantes en el nivel de actividad proteinasa, retención superficial, y contenido proteínico. El cambio de las proteínas en la cerveza durante el almacenaje y relación entre proteinasa A y prote­ínas de espuma también fueron estudiadas. Los resultados de electro­foresis en gel policrilamida de sodio dodecil sulfato indicaron que la protein1 de transferencia lípido fue degradada y ésta proteína activa en espuma es un substrato importante de proteinasa A. La degradación de la proteína 1 de transferencia lípido es un factor mayor que causa una dismi­nución en la estabilidad de la espuma en la cerveza. Palabras claves: Estabilidad de espuma, Pasterización, Proteína, Proteína 1 de transferencia lípido