FIG. 4.
Inactivation kinetics of L. innocua NCTC 11289 with different pulse lengths. Data were obtained after PEF treatment with electric field strengths of 2.8 V/μm (A through C) and 3.6 V/μm (D through F). (A, B, D, and E) Log reduction plotted versus the temperature after treatment (outlet temperature) (A and D) and versus the number of pulses (B and E). Symbols: ■, 2-μs pulse; ⧫, 3-μs pulse; ●, 3.9-μs pulse. (C and F) Relationship between the energy input and the pulse length at various levels of inactivation levels. Symbols: ⧫, 2-log reduction; ●, 3-log reduction; ▴, 6-log reduction. The pH of the treatment medium was 5, and the inlet medium temperature was 40°C. The inoculum contained 1.4 × 106 CFU/ml. The results are means based on data from two experiments, and standard deviations are indicated by error bars. Nt, number of survivors after treatment; N0, number of cells before treatment.