Sterilization of Microorganisms with Supercritical Carbon Dioxide

Inactivation of food poisoning bacteria and Geobacillus stearothermophilus spores by high pressure carbon dioxide treatment

“…At moderate temperature and pressure, HPCT significantly inactivates bacterial vegetative cells, whereas, pressure treatment has little effect at room temperature at moderate pressure such as 5-35 MPa on bacterial spores (Knorr & Heinz, 2001;Sonoike, 1997). There have been a few studies on the inactivation of bacterial spores by HPCT (Ballestra & Cue, 1998;Dillow, Dehghani, Hrkach, Foster, & Langer, 1999;Enomoto, Nakamura, Nagai, Hashimoto, & Hakoda, 1997;Ishikawa et al, 1997;Kamihira, Taniguchi, & Nobayashi, 1987). In those studies, HPCT can substantially inactivate bacterial spores at temperatures above 50°C except for Geobacillus stearothermophilus, and some other studies showed that the treatment at room temperature is not significant for the inactivation of bacterial spores by HPCT.…”

Avicel hydrolysis by cellulase enzyme in supercritical CO2

“…Several different reactions include the oxidation of substituted phenols by polyphenol oxidase (Hammond et al, 1985), the conversion of p-nitrophenylphosphate to p-nitrophenol by an alkaline phosphatase (Randolph et al, 1985), the oxidation of cholesterol by cholesterol oxidase (Randolph et al, 1988), and synthesis of aspartame precursors by thermolysin (Kamihira et al, 1987). There are two reviews which provided a brief overview of work in this field (Russell et al, 1994;Savage et al, 1995).…”

Inactivation of Aspergillus Spores in Clinical Wastes by Supercritical Carbon Dioxide

“…Xu et al [59] showed that pectin methylesterase reduced by 54.3 % at 22 MPa, 60 • C for 10 min, while polyphenol oxidase was completely inactivated. The inactivation of enzymes by SC-CO 2 is due to react CO 2 with water in the microorganism cell to form carbonic acid, the low pH and pressure cause destabilizes of enzyme by dissociation of the enzyme subunits or loss their correct assembly structure which may be reversible or irreversible [60][61][62]. The results indicated that CO 2 has penetrated the spore cell wall into the spore protoplasm and inactivated the enzymes [63].…”

“…Several authors observed that the treatment by SC-CO 2 led to burst cells, wrinkles and holes on the cell surface [60,[66][67][68][69]. SC-CO 2 has gas-like viscosity and liquid-like density; thus, SC-CO 2 easily penetrates into complex structures and extract of solutes [70].…”