High intensity pulsed electric fields applied to egg white: effect on Salmonella Enteritidis inactivation and protein denaturation.

High-intensity electric fields have been successfully applied to the destruction of Salmonella Enteritidis in diaultrafiltered egg white. The effects of electric field strength (from 20 to 35 kV x cm(-1)), pulse frequency (from 100 to 900 Hz), pulse number (from 2 to 8), temperature (from 4 to 30 degrees C), pH (from 7 to 9), and inoculum size (from 10(3) to 10(7) CFU x ml(-1)) were tested through a multifactorial experimental design. Experimental results indicate that, for Salmonella inactivation, the electric field intensity is the dominant factor with a strongly positive effect, strengthened by its positive interaction with pulse number. Pulse number, temperature, and pH have also significant positive effects but to a lesser extent. In the most efficient conditions, the pulsed electric field (PEF) treatment is capable of 3.5 log10 reduction in viable salmonellae. Simultaneously, the measure of surface hydrophobicity does not indicate any increase after PEF treatment. These results suggest that no protein denaturation occurs, unlike what is observed after comparable heat treatment in terms of Salmonella inactivation (55 degrees C for 15 min).

[Choice of antiseptics for use in footbaths for cattle (author's transl)]. / Le choix des antiseptiques pour les pédiluves destinés aux bovins.

Eight antiseptics to be used in footbaths for cattle, were compared : formol, cuprum sulphate, formol associated with cuprum sulphate, Javel water, Crésyl and some other products more recently introduced into practice. For each one, evolution of antibacterial activity connected with utilization on animals, moistening power and possible injury caused were observed. The best results have been obtained with formol, formol associated with cuprum sulphate and Cresyl which have exhibited persistent high level antibacterial activity without related injury in spite of numerous applications. On the other hand, weak organic matter resistance which seems to characterize Javel water, synthetic phenols, amphoteric amino acids and iodophores makes them unsuitable for use in footbaths.