title: Inactivation of Escherichia coli, Saccharomyces cerevisiae, and Lactobacillus brevis in Low-fat Milk by Pulsed Electric Field Treatment: A Pilot-scale Study.
abstract: We investigated the effects of a pulsed electric field (PEF) treatment on microbial inactivation and the physical properties of low-fat milk. Milk inoculated with Escherichia coli, Saccharomyces cerevisiae, or Lactobacillus brevis was supplied to a pilot-scale PEF treatment system at a flow rate of 30 L/h. Pulses with an electric field strength of 10 kV/cm and a pulse width of 30 μs were applied to the milk with total pulse energies of 50-250 kJ/L achieved by varying the pulse frequency. The inactivation curves of the test microorganisms were biphasic with an initial lag phase (or shoulder) followed by a phase of rapid inactivation. PEF treatments with a total pulse energy of 200 kJ/L resulted in a 4.5-log reduction in E. coli, a 4.4-log reduction in L. brevis, and a 6.0-log reduction in S. cerevisiae. Total pulse energies of 200 and 250 kJ/L resulted in greater than 5-log reductions in microbial counts in stored PEF-treated milk, and the growth of surviving microorganisms was slow during storage for 15 d at 4℃. PEF treatment did not change milk physical properties such as pH, color, or particle-size distribution (p<0.05). These results indicate that a relatively low electric-field strength of 10 kV/cm can be used to pasteurize low-fat milk.
authors.affiliation: Department of Food Science and Technology, Chung-Ang University, Anseong 17546, Korea.
authors.forename: Gun Joon
authors.initials: GJ
authors.lastname: Lee
authors.affiliation: BK Bio Co. Ltd., Seongnam 13403, Korea.
authors.forename: Bok Kung
authors.initials: BK
authors.lastname: Han
authors.affiliation: BK Bio Co. Ltd., Seongnam 13403, Korea.
authors.forename: Hyuk Joon
authors.initials: HJ
authors.lastname: Choi
authors.affiliation: R&D Center, Seoul Dairy Co-op, Ansan 15407, Korea.
authors.forename: Shin Ho
authors.initials: SH
authors.lastname: Kang
authors.affiliation: R&D Center, Seoul Dairy Co-op, Ansan 15407, Korea.
authors.forename: Seung Chun
authors.initials: SC
authors.lastname: Baick
authors.affiliation: Department of Food Science and Technology, Chung-Ang University, Anseong 17546, Korea.
authors.forename: Dong-Un
authors.initials: DU
authors.lastname: Lee
keywords: low-fat milk; microbial inactivation; pasteurization; physical property; pulsed electric field