Disinfection of wheat grains contaminated with Penicillium oxalicum spores by a supercritical carbon dioxide-water cosolvent system

Spores of the plant pathogenic fungus Penicillium oxalicum inoculated onto wheat grains were inactivated using supercritical carbon dioxide (SC-CO2). After the SC-CO2 treatment at various conditions of temperature, time and amount of water cosolvent, the colony forming units (CFU) of fungal spores on wheat grains and the germination yields of wheat grains were determined. Among these SC-CO2 treatment parameters, the inactivation of P. oxalicum spores was found to be significantly increased by adding water cosolvent. The optimal conditions determined by ridge analysis of response surface methodology were 233 μL water, 44 °C, and 11 min, which resulted in a 6.41 log10 CFU reduction of P. oxalicum. However, the germination yields of wheat grains significantly decreased when water cosolvent of 150 or 300 μL was added to the grains contained in the 100 mL SC-CO2 treatment vessel.