Direct application of supercritical carbon dioxide for the reduction of Cronobacter spp. (Enterobacter sakazakii) in end products of dehydrated powdered infant formula

Abstract

The objective of this study was to develop a viable new method for inactivation of Cronobacter spp. that could be applied directly to dehydrated powdered infant formula (PIF) using supercritical carbon dioxide (SC-CO2). Samples inoculated with Cronobacter spp. were subjected to SC-CO2 treatment under various conditions (temperature: 63, 68, and 73°C; pressure: 15, 20, and 25MPa; time: 10, 20, and 30min). The survival of Cronobacter spp. was assayed, as were any changes in the quality of the treated PIF. Inactivation of Cronobacter spp. by SC-CO2 was enhanced as temperature and pressure conditions increased (>6.32 log10 cfu/g). In a validation assay using low-level inoculation (3.21 log10 cfu/g), treatment at 73°C and 15MPa for 30min, 20MPa for 20 and 30min, or 25MPa for 20 and 30min reduced Cronobacter spp. to undetectable levels, with no recovery of cell viability. There was no significant change in water activity, pH, and color of the treated PIF. Overall, the optimum conditions for elimination of Cronobacter spp. were determined to be 73°C and 20MPa for 20min. These parameters for effective SC-CO2 treatment are feasibly applicable to end product of dehydrated PIF. The results of our study may contribute to the development of an efficient method for improving the microbiological safety of PIF. © 2010 American Dairy Science Association.