Determining Pasteurization Units from Residual Melibiase Activity in Lager Beer

Abstract

A method was developed to determine the number of pasteurization units a lager beer has received from measurements of beer pH and residual melibiase (α-galactosidase) activity. A procedure for determining the melibiase activity is given. For a given pH and temperature, the heat inactivation of melibiase was shown to follow an exponential decay. Then 35 heat inactivation constants (k) were determined at seven pH values (pH 3.90–4.50) for five temperatures (60.0–64.1°C) for two lager beers. Based on either the experimental or the computed values for k at pH 4.0–4.5, a method is outlined for assessing the number of pasteurization units of a lager beer. For beer pasteurized at 60° C, it was possible to estimate up to 30–125 PU, depending on the pH of the beer. The melibiase method was judged to be accurate to ± 20%.

• Enzyme
• α-Galactosidase
• Heat inactivation
• Lager beer
• Melibiase
• Pasteurization