Analysis of the inactivation kinetics of freeze-dried á-amylase from bacillus amyloliquefaciens at different moisture contents

The thermal inactivation kinetics of freeze-dried á-amylase in a solid matrix was studied at water contents ranging from 1.5 to 23.9 g water per 100 g dry solid. These conditions were obtained by equilibration in dry environments, with water activities ranging between 0.11 and 0.88. Isothermal inactivation experiments in the range 135 to 150 °C were performed. Results were analysed with both the Bigelow and Arrhenius models. It was concluded that there was no statistical significance to suggest that the water content influenced the kinetic parameters. An activation energy of 128 kJ/mol and pre-exponential factor with a logarithm of 33.9 described all the results well