Bacterial inactivation using pulsed electric fields

Abstract

Thermal pasteurization (TP) of milk ensures the safety of the product. However, raw milk loses its valuable nutrients and sensory characteristics due to substantial heat exposure. Pulsed electric fields (PEF) were investigated as an alternative to TP techniques. PEF could be a new quality maintaining pasteurization technique that is safe and cost effective. Pasteurized and inoculated with E.coli O157:H7 milk (2.5% fat) was PEF-treated with PEF using 20 pulses of 24 kV/cm electric field strengths, pulse duration 25 μs, and compared with inoculated samples TP-treated at 80°C for 20 s; at 65°C for 30 min and combined TP – MF treatment, at 80°C for 20 s with membrane of 0.5 μm. Comparison PEF, TP TP-MF for reduction in count of E.coli in milk, revealed that no colonies of surviving E.coli were detected in TP, TP-MF treated samples.