Effect of pulsed electric field processing parameters on Salmonella enteritidis inactivation

摘要

Pilot scale continuous pulsed electric field treatment of liquid products was tested on the effects of energy input (0 < Q < 300 kJ kg~(-1)), electric field strength (25 < E < 70 kV cm~(-1)), square wave pulse width (0.05, 0.1, 0.25, 0.5, 1, 2 and 3 μs) and initial product temperature (4 < T_(INIT) < 20℃) on Salmonella enteritidis inactivation in a model solution composed of 28 mM sodium sulfate and 28 mM glucose. For Q = 0-100 kJ kg~(-1), the decimal reduction number [DRN = log(N_0/N)] can be considered as linearly related to Q with the decimal reduction energy [Q_D] varying between 44 ± 3.2 kJ kg~(-1) for 0.05 μs, 37 ± 2.5 kJ kg~(-1) for 0.1 μs and 32 ± 1.4 kJ kg~(-1) for 0.25-3 μs pulse width. For Q = 0-300 kJ kg~(-1), the relation between Q and log(N_0/N) was of power law type with the threshold energy level Q_0 = 9 ± 2.6 kJ kg~(-1) and the power coefficient 3.17 ± 0.21. For Q = 65 kJ kg~(-1) the increase of T_(INIT) by 6.6(± 0.7)℃ raises the DRN by one unit. The same effect increased the products' electrical resistance by 16(± 1.4) Ω. For an overall treatment time of 1 μs, the DRN is linearly related to E, with threshold (E_0) and decimal reduction (E_D) electric field strength: E_0 = 19 ± 1.8 and E_D = 29.7 ? 1.2 kV cm~(-1), respectively.