I. The development of an enzymic time temperature integrator to assess thermal efficacy of sterilization of low‐acid canned foods

Abstract

Heat inactivation kinetics of Bacillus subtilis α‐amylase at reduced moisture content was studied under steady state and under non‐steady state conditions by monitoring the decrease in enthalpy associated with the heat deterioration of the enzyme. The high thermostability of the enzymic systems, obtained due to a reduction of the moisture content, allowed the systems to be applied in sterilization processes. Moreover, because Bacillus subtilis α‐amylase equilibrated above a saturated salt solution of an equilibrium relative humidity of 76 at 4°C yielded a z‐value of 9.7°C, this system can be used to monitor the thermal destruction of spores of proteolytic strains of Clostridium botulinum, characterized by a z‐value of 10°C, and hence, allows the measurement of the lethal efficacy of a sterilization process of low acid canned foods.