Comparison of supplements to enhance recovery of heat-injuredSalmonellafrom egg albumen

Abstract

The purpose of this study was to determine the proficiency of supplements to enhance the recovery of Salmonella from heat-treated liquid egg albumen on solid agar media. Salmonella-inoculated albumen, heated at 53.3 degrees C for 4 min, was plated on 39 combinations of solid media with or without the addition of 12 supplements. Greater numbers of Salmonella (P < 0.05) recovered with the addition of 1.0 g l(-1) ferrous sulfate (FeSO(4)) than with any other supplements, except for 0.5 or 1.0 g l(-1) 3'3'-thiodipropionic acid (TDP), which recovered equivalent populations. Addition of 1.0 g l(-1) sodium pyruvate or 6.0 g l(-1) yeast extract plus 1.0 g l(-1) sodium pyruvate supported greater resuscitation than unsupplemented tryptic soy agar (TSA) or supplementing with 0.01 or 0.1 g l(-1) N-propyl gallate, 10 g l(-1) activated charcoal, 0.1 g l(-1) KMnO(4) or 50 mg l(-1) ethoxyquin. The remaining supplements supported recovery of equivalent numbers of Salmonella, which were fewer cells than recovered with 1.0 g l(-1) FeSO(4), yet greater populations than recovered with 50 mg l(-1) ethoxyquin. Supplementation of plating media with FeSO(4), TDP or sodium pyruvate enhanced recovery of sublethally injured Salmonella from albumen. Pasteurizing albumen impedes recovery of pathogens. These results suggest that the addition of supplements to plating media may assist resuscitation and colony development of heat-injured salmonellae.