Effect of pH and Chelating Agents on the Heat Resistance and Viability of Salmonella typhimurium Tm-1 and Salmonella senftenberg 775W in Egg White

摘要

Supplementation of egg white at pH 8.9 with 5 mg of disodium ethylenediaminetetraacetic acid (EDTA) per ml resulted in a kill of Salmonella typhimurium Tm-1 of greater than 106 per ml after 28 days at 2 C. While at 28 C, supplementation with 7 mg of EDTA per ml resulted in approximately a 106 kill in less than 24 hr. Kena supplementation at 40 mg/ml of egg white resulted in a kill of S. typhimurium Tm-1 of greater than 106 after approximately 60 hr of storage at 28 C. This is in contrast to no reduction in viable count in unsupplemented egg white stored at 2 C and a 100-fold increase in viable count in that stored at 28 C. Supplementation of egg white with EDTA at 7 mg/ml or with Kena at 10 mg/ml also affected the heat resistant characteristics of the two organisms at 52.5 C, reducing the time required to kill 90% of the population (D value) at any pH by a factor of 2 to 6. There was a synergistic effect between EDTA and lactic acid when lactic acid was used to adjust EDTA-supplemented egg white to an acidic pH (5.3) which greatly decreased the heat resistance of Salmonella senftenberg 775W (from 100D to D).