Inactivation of Salmonella, Listeria monocytogenes and Escherichia coli O157:H7 inoculated on coriander by freeze-drying and supercritical CO2 drying

Although dried foods are considered microbiological stable foods and show adverse conditions to microbial growth, they may still host pathogenic microorganisms, which may proliferate upon sufficient rehydration. Highly contaminated commodities such as herbs and spices can pose a threat to consumer health if not processed carefully. There is therefore a need to develop or improve drying techniques which can provide dried foods while reducing the initial contamination to acceptable levels in a single process. CO2 is a cheap, accessible solvent, with a low critical point (31 °C, 73.8 bar). Moreover, in the supercritical region, CO2 exhibits potent microbicidal properties. Therefore, supercritical CO2 drying could be a valuable alternative non-thermal technique for conventional drying methods, such as air-drying or freeze-drying, when medium to high value-added food products with high initial contamination are involved.