Calorimetric determination of inactivation parameters of micro-organisms.
OBJECTIVE
This study aimed to apply differential scanning calorimetry (DSC) to evaluate the thermal inactivation kinetics of bacteria.


RESULTS
The apparent enthalpy (DeltaH) of Escherichia coli cells was evaluated by a temperature scan in a DSC after thermal pretreatment in the calorimeter to various temperatures between 56 and 80 degrees C. Conventional semilogarithmic survival curve analysis was combined with a linearly increasing temperature protocol. Calorimetrically determined D and z values were compared to those obtained from plate count data collected under isothermal conditions to validate the new approach.


CONCLUSIONS
The calculated D values using both apparent enthalpy and viability data for cells heat treated in the DSC were similar to the D values obtained from isothermal treatment. Temperatures for 1 through 10-log microbial population reductions, calculated from plate count and enthalpy data, were in agreement within 0.5-2.4 degrees C at a 4 degrees C min-1 heating rate.


CONCLUSIONS
This novel calorimetric method provides an approach to obtain accurate and reproducible kinetic parameters for inactivation. The calorimetric method here described is time efficient and is conducted under conditions similar to food processing conditions.
Lee
J
J
Department of Food, Agricultural, and Biological Engineering, The Ohio State University, Columbus 43210, USA.
Kaletunç
G
G
D002152:Calorimetry, Differential Scanning; D015169:Colony Count, Microbial; D004926:Escherichia coli / Q000254:growth & development*; D005506:Food Contamination / Q000517:prevention & control; D005516:Food Microbiology; D006358:Hot Temperature; D008954:Models, Biological; D013242:Sterilization / Q000379:methods*