TITLE:
Effects of Far-Infrared Irradiative Heating Pasteurization on Fungi
AUTHORS:
Tubasa Nakata, Arisa Okamoto, Jun Sawai, Mikio Kikuchi
KEYWORDS:
Far-Infrared, Radiative Heating, Thermal Conductive Heating, Death Rate Constant, Yeast, Fungal Spore
JOURNAL NAME:
Journal of Biosciences and Medicines,
Vol.3 No.7,
July
14,
2015
ABSTRACT: The effect of far-infrared (FIR) irradiation pasteurization on fungi was quantitatively evaluated and compared with the effect of thermal conductive heating. After the bulk temperature of the sterile saline irradiated by FIR reached a steady given temperature, yeast cells (Candida albicans NBRC 1950 and Saccharomyces cerevisiae NBRC 1067) or fungal spores (Aspergillus niger NBRC 4781) were inoculated and FIR heating was conducted. A mullite cylinder FIR heater, with a main wavelength of 4 - 7 μm, was used for FIR heating. Death of fungi by FIR heating and by thermal conductive heating both followed first-order reaction kinetics, and the apparent death rate constants under different temperature conditions were obtained. For the same bulk temperatures, pasteurization by FIR heating was more effective than thermal conductive heating. The activation energy for the death of fungi by FIR irradiation was slightly lower than thermal conductive heating, indicating differences in the mechanism of action.