Effect of High Hydrostatic Pressure-Temperature Combinations on the Activity of β-Glucanase from Barley Malt

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Abstract
β-Glucanase from barley malt is known to be thermolabile but important in the mashing process. Therefore, the potential of increasing the thermostability of β-glucanase in ACES buffer (0.1 M, pH 5.6) by high hydrostatic pressure has been investtigated. 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°C were assessed by analyzing the kinetic rate constants. A significant stabilization of β-glucanase against temperature-induced inactivation was detected at 400 MPa. With increasing pressure up to 600 MPa the catalytic activity of β-glucanase was progressively decelerated. However, for the overall depolymerization reaction of β-glucans in ACES buffer (0.1 M, pH 5.6) a maximum was identified at 215 MPa and 55°C yielding approximately 2/3 higher degradation of β-glucan after 20 min as compared to the maximum at ambient pressure (45°C).