The effects of pulsed electric fields (PEF) on the inactivation of Salmonella Enteritidis inoculated into liquid whole egg (LWE) and on the physical properties and the shelf‐life of LWE were studied. PEF processing conditions were 1.2 mL/s flow rate, 200 pps frequency, 2.12 μs pulse duration, 25 kV/cm electric field strength, and 250 μs total treatment time. The PEF processing caused up to 1 log10 cfu/mL reduction in S. Enteritidis population in LWE. The PEF‐treated samples were subjected to heat at 55C for 3.5 min to inactivate the remaining bacteria without denaturing the LWE. The combination of PEF and heat treatments led to a 4.3 log10 cfu/mL reduction in S. Enteritidis population (P < 0.05) and caused no significant change in viscosity, electrical conductivity, color, pH, and Brix, relative to control samples (P > 0.05). The PEF+55C treated LWE samples presented significantly longer shelf‐life at 4C compared with the control and heat treated samples (P < 0.05).
Pulsed electric field (PEF) exposes a fluid or semi-fluid product to short pulses of high-energy electricity, which can inactivate microorganisms. The efficacy of PEF treatment for pasteurisation of liquid eggs may be a function of processing temperature. In this study, effects of PEF, temperature, pH and PEF with mild heat (PEF + heat) on the inactivation of Salmonella typhimurium DT104 cells in liquid whole egg (LWE) were investigated. Cells of S. typhimurium were inoculated into LWE pH adjusted to 6.6, 7.2 or 8.2 at 15, 25, 30 and 40°C. The PEF field strength, pulse duration and total treatment time were 25 kV cm )1 , 2.1 ls and 250 ls respectively. Cells of S. typhimurium in LWE at pH 7.2 were reduced by 2.1 logs at 40°C and 1.8 logs at 30°C. The PEF inactivation of S. typhimurium cells at 15 or 25°C was pH dependent. Heat treatment at 55°C for 3.5 min or PEF treatment at 20°C resulted in c. 1-log reduction of S. typhimurium cells. Combination of PEF + 55°C achieved 3-log reduction of S. typhimurium cells and was comparable to the inactivation by the heat treatment at 60°C for 3.5 min. With further development, PEF + heat treatment may have an advantage over high-temperature treatment for pasteurisation of liquid eggs.
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