ARS | Publication request: ENDOPROTEINASES OF BARLEY AND MALT AND THEIR ENDOGENOUS INHIBITORS

Submitted to: Cereal Conference Royal Australian Chemical Institute Proceedings
Publication Type: Proceedings
Publication Acceptance Date: September 10, 1995
Publication Date: N/A

Technical Abstract: Correctly hydrolyzing barley proteins during malting and mashing is very important to the production of good beer. In my laboratory, we have been characterizing the enzymes involved in the protein hydrolysis system so that new barleys with maximized malting and mashing quality can be more efficiently developed. We began this research by purifying and characterizing two cysteine endoproteinases that appear to play major roles in protein hydrolysis during malting. We have since changed over to using two-dimensional separation methods for studying the entire complement of endoproteinases active during malting and mashing. These methods show that there are about 50 different endoproteinase activities in green malt, including representatives of all four proteinase classes. While carrying out these studies, it became obvious that there were compounds in both barley and kilned malt that inhibited the activity of some (mostly cysteine-class) of the endoproteinases present in green malt. These, we have termed 'endogenous proteinase inhibitors'. We have characterized these endogenous inhibitors and have purified and identified two of them. Several more remain to be purified and characterized. The protein-hydrolyzing system of germinating barley is thus seen to be a very complex system, not the relatively simple one previously proposed.