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

Abstract

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 Tref 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.