Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 6/11/2009
Publication Date: 10/4/2009
Citation: Ukuku, D.O. 2009. Difference in cellular damage and cell death in thermal death time disks and high hydrostatic pressure treated Salmonella Enteritidis (ATCC13076) in liguid whole egg. Proceedings of the United States-Japan Cooperative Program In Natural Resources (UJNR). Food and Agriculture Panel 38th Annual Meeting. October 3-9, 2009, Tsukuba, Japan. p. 107-110.
Technical Abstract: Differences in membrane damage including leakage of intracellular UV-materials and loss of viability of Salmonella Enteritidis (ATCC13076) in liquid whole egg (LWE) following thermal-death-time (TDT) disk and high hydrostatic pressure treatments were examined. Salmonella enteritidis was inoculated in LWE to a final 7.4 log10 CFU/ml and were thermally treated with TDT disks at 23 C, 45, 50, 55 and 60 C, from 0 to 240 s or pressurized at 350 MPa at 25 C, 35 C and 45 C for 30 min. Sublethal injury, leakage of UV-materials and viability loss as a function of membrane damage was investigated by plating 0.1 ml of treated and untreated samples of non selective Trypticase Soy Agar (TSA) and selective Xylose Lysine Sodium Tetradecylsurate (XLT4) plates with incubation at 36 C for 48h. Sub-lethal injury occurred in Salmonella populations thermally treated at 55 C and above for 120 s while pressure treatment at 25C for 30 min caused similar sub-lethal injury. Leakage of intracellular UV-materials and ATP of TDT disk injured cells was lower than the values determined from pressurized cells. Similarly, recovery of TDT injured cells occurred faster than pressurized cells during storage of treated samples at 25 C. The results of this study indicate that pressure treatment of 350 – MPa at 30 C for 30 min and thermal treatments of 55 and 60 C caused a substantial damage to Salmonella membranes, leading to leakage and accumulation of intracellular bacterial substances in the treated samples.