Abstract
This study evaluated the effectiveness of a supercritical carbon dioxide (SCCO 2) system, with a gas–liquid porous metal contactor, for reducing Escherichia coli K12 in diluted buffered peptone water. 0.1% (w/v) buffered peptone water inoculated with E. coli K12 was processed using the SCCO 2 system at CO 2 concentrations of 3.1–9.5 wt%, outlet temperatures of 34, 38, and 42 °C, a system pressure of 7.6 MPa, and a flow rate of 1 L/min. Increased CO 2 concentrations and temperatures significantly ( P < 0.05) enhanced microbial reduction. A maximum reduction of 5.8-log was obtained at 8.2% CO 2 and 42 °C. To achieve a 5-log reduction of E. coli K12 in 0.1% buffered peptone water, minimum CO 2 concentrations of 9.5%, 5.5%, and 5.3% were needed at 34, 38, and 42 °C, respectively. Further reductions of cells were observed after storage for 7 days at 4 °C. But storage at 25 °C increased the number of viable cells to 8-log cfu/mL after 7 days. This study showed the potential of the pilot scale SCCO 2 system with a gas–liquid porous metal contactor for microbial inactivation in liquid food.
Published Version
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