Effect of high hydrostatic pressure-temperature combinations on the activity of β-glucanase from barley malt

beta-Glucanase from barley malt is known to be thermolabile but important in the mashing process. Therefore, the potential of increasing the thermostability of beta-glucanase in ACES buffer (0.1 M, pH 5.6) by high hydrostatic pressure has been invest-tigated. Inactivation of the enzyme as well as changes of the conversion rate in response to combined pressure-temperature treatments in the range of 0.1-900 MPa and 30-75 degrees C were assessed by analyzing the kinetic rate constants. A significant stabilization of beta-glucanase against temperature-induced inactivation was detected at 400 MPa. With increasing pressure up to 600 MPa the catalytic activity of beta-glucanase was progressive, ly decelerated. However, for the overall depolymerization reaction of beta-glucans in ACES buffer (0.1 M, pH 5.6) a maximum was identified at 215 MPa and 55 degrees C yielding approximately 2/3 higher degradation of beta-glucan after 20 min as compared to the maximum at ambient pressure (45 degrees C).