Energy analysis of liquid whole egg pasteurized by pulsed electric fields Original Research Article

Non-thermal preservation of liquid whole egg (LWE) with pulsed electric fields (PEF) is an attractive alternative to thermal processing where protein coagulation is of concern. The objective of this study was to evaluate the energy applied under different PEF processing conditions and its effect on the microbial quality of LWE during refrigerated storage. The LWE was stabilized with citric acid (CA) at 0.15% and 0.5% to prevent color darkening. Inside a pilot plant-size PEF chamber, the peak values of the electric field traces at the high-voltage electrode, middle gap, and low-voltage electrode were 37, 30, and 25 kV/cm, respectively. The pulse width was 1.84 μs, with energy density at 11.9 J/ml per pulse. The total treatment time varied from 54 to 478 μs (corresponding with 30–266 slightly underdamped pulses). The microbiological quality of the LWE was monitored weekly while under refrigerated storage at 4 °C. The CA not only acted as a color stabilizer but also increased the effectiveness of PEF treatment. The maximum shelf-life sustained at 4 °C of LWE with 0.15% CA was 20 days, with PEF treatments up to 489 μs (266 pulses) at an average electric field of 30 kV/cm. The total processing energy delivered to this product was 6331 J/ml. LWE with 0.5% CA had a shelf-life of almost 30 days at 4 °C, using a maximum PEF energy expenditure of 357 J/ml (30 pulses or 55 μs of 30 kV/cm).