Concentrated high intensity electric field ( CHIEF ) pasteurization of milk

Concentrated high intensity electric field (CHIEF) is non-thermal pasteurization technology that uses microsecond pulses of electricity to inactivate bacteria without causing undesirable changes in flavor or quality of a product. This technology was explored as an alternative to current milk pasteurization processes, and was examined for its effects on microbial stability, sensory, quality and shelf life of milk. Milk samples containing an initial inocula of approximately 108 CFU/mL of mixtures of Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes or an initial inocula of 103 CFU/mL of viable Bacillus cereus spores were treated with our CHIEF system. The average (± standard deviation) of microbial inactivation after subjecting milk samples to a single pass through CHIEF was 2.74 (± 1.0), 2.95 (± 0.35), 2.75 (± 0.25), and 0.18 (± 0.15) log CFU/ml for E. coli O157: H7, Salmonella, L. monocytogenes and Bacillus cereus, respectively. When the milk samples were pumped twice through CHIEF, reductions of 4.36 (± 0.24), 5.55 (± 0.14), and 4.78 (± 0.78) log CFU/ml for E. coli O157:H7, Salmonella, and L. monocytogenes, respectively, were observed. Additional passes with our current system are expected to result in more bacterial reduction. These results suggest that the CHIEF process has the potential to deliver similar microbial inactivation effectiveness as a standard HTST pasteurization system.