Inactivation of Bacillus subtilis spores by supercritical CO2 treatment
2003
Spilimbergo, S. | Bertucco, A. | Lauro, F.M. | Bertoloni, G.
Bacillus subtilis spores were suspended in saline solution (107 cfu/ml) and treated by both conventional heating and CO2 batch treatment at an operating pressure in the range of 70–150 bar under identical temperature conditions. Temperatures tested were in the range of 36–75 °C. Survival curves indicated significantly higher lethality when spores were treated with supercritical CO2 (SC-CO2) rather than with heating alone. These results appear particularly evident at 60 °C, a temperature at which conventional heating gave no spore-inactivation after a treating time as long as 24 h, whereas a 6 h SC-CO2 treatment led to complete sterilization. At 75 °C spores were partially killed with conventional heating but a treatment of 2 with SC-CO2 hours assured total inactivation. It is concluded that spore-inactivation during SC-CO2 treatment was only in part due to thermal effect (at the higher temperature of 75 °C) and there was a significant additional effect caused by CO2 penetration inside the latent bacteria forms.
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