Model studies characterizing the rheological behavior of simulated mashing conditions using the rapid visco-analyzer

This paper reports on the application of the rapid visco-analyzer (RVA) to further understand rheological changes that 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 and subsequent starch digestibility. In addition, secondary starch gelatinization rheological data representing consistency-viscosity increases because of the presence of smaller starch granules were clearly correlated with the level of mash amylase. The influence of mash pH on starch gelatinization/liquefaction and amylase activities could be quantified from the rheological data. Clear correlations were found between the added levels of P-glucanase on a P-glucan substrate and the recorded rheological trends. Overall, the studies clearly show the interactions between grain components (purified/nonpurified), amylolytic enzymes, glucanolytic enzymes, and mash pH and how they individually and collectively influence the consistency-viscosity profiles during the mashing process. In addition, the results further validate the RVA as being a suitable instrument for determining mash rheological changes. Application of the methods can provide the maltster, brewer, or distiller with more functional information regarding raw materials and process conditions.