Inactivation model of mold spores by infrared heating under non-isothermal conditions

The inactivation effect of infrared (IR) heating (peak wavelength of the lamp = 0.96 ìm) at different intensities on two kinds of mold conidia (Cladosporium sp. and Penicillium sp.) isolated from peaches was investigated on an agar growth medium. Treatment times of 40 s and 60 s were required for a one log reduction in the population of Cladosporium sp. and Penicillium sp. microorganisms at a heating distance of 90 mm. The high resistance to IR heating exhibited by Penicillium sp. was caused by its high lethal temperature (T _ref) of 326 K, whereas T_ref of Cladosporium sp. is much lower at 316 K. The first order kinetics model parameters under non-isothermal conditions were obtained from the data. The prediction model agreed well with the experimental data with a Root Mean Squared Logarithmic Error (RMSLE) of 0.74 and 0.45 for Cladosporium sp. and Penicillium sp., respectively.