Model studies to understand the effects of amylase additions and pH adjustment on the rheological behaviour of simulated brewery mashes

Abstract

This paper reports on the application of a previously published laboratory scale rheological method to understand the effects that amylase addition and pH adjustment have on the rheological changes, which are taking place during the brewery mashing process. Clear correlations were found between the level of amylase present in mashes and the rheological data points representing primary grain/starch swelling (PVG, R2 = 0.9821) and subsequent starch digestibility (BR44, R2 = 0.9751). In addition, secondary starch gelatinisation rheological data representing viscosity increases due to the presence of smaller starch granules were clearly correlated with the level of mash amylase (VG2D, R2 = 0.9882). The influence of mash pH on starch gelatinisation/breakdown and amylase activities could be quantified from the rheological data. Overall, the studies clearly show how grain components, amylolytic enzymes and mash pH collectively influence the viscosity profiles during the mashing process. In addition, application of the method can provide the maltster/brewer/distiller with more functional information regarding raw materials and process conditions. © 2005 The Institute of Brewing & Distilling.