Hygienization of mixed animal by-product using Pulsed Electric Field: Inactivation kinetics modeling and recovery of indicator bacteria

The hygienization of animal by-products (ABP) assisted by Pulsed Electric Field (PEF) was studied as a transfer of the innovative athermal pasteurization technology developed in food engineering to replace the conventional thermal hygienization process. The strains Enterococcus faecalis ATCC 19433 and Escherichia coli ATCC 25922 were selected as indicator bacteria. A systematical investigation was carried out concerning the inactivation kinetics of the indicator bacteria at different electric field strength (10, 15, 20 and 25 kV.cm(-1)), the kinetic modeling using coupled Weibull model, the effect of PEF energy input and the recovery of PEF-injured bacteria at 3 degrees C for 7 days. Results show that a PEF treatment at 25 kV.cm(-1) for an effective time over 30 ms would be sufficient to achieve a 5-log10 reduction of Ent. faecalis. It complies with the EU regulation No. 142/2011 to validate an alternative hygienization technology other than thermal pasteurization. The Weibull model coupled with a secondary model proved efficient to estimate the survival kinetic curves of two indicator bacteria treated by PEF. The injured E. coli could not regenerate after PEF exposure while Ent. faecalis could get self-recovery. This preliminary work confirms that PEF was able to give the hygienization of ABP in terms of the bacterial reduction requirement of EU.