Submitted to: Journal of the American Society of Brewing Chemists
Publication Type: Abstract Only
Publication Acceptance Date: 6/21/1997
Publication Date: N/A
Technical Abstract: The proteinases of germinating barley hydrolyze storage proteins into amino acids and small peptides that can be used by the growing plant or, during brewing, by yeast. They are critical for malting and brewing because several aspects of the brewing process are affected by the amounts of protein, peptide or amino acids present. In order to produce improved malting barley varieties and to improve malting and brewing methods, it is imperative that we know when (or whether) the green malt endoproteinases are destroyed during either malting or mashing. This study was carried out to determine which endoproteinases are present in green malt, whether they are stable to the high temperatures of malting kilning, and when, during mashing, the proteinases are inactivated. Our results indicate that most of the green malt endoproteinases are totally stable throughout kilning. They are stable through the protein rest phase of mashing, but are quickly degraded when the mash temperature is raised to 72C for conversion. This information will help researchers develop barleys that have improved malting quality and indicates to maltsters and brewers how they can vary their processing methods to adjust the 'soluble protein' levels of their products.