Submitted to: Meeting Abstract
Publication Type: Abstract only
Publication Acceptance Date: 3/3/2006
Publication Date: 6/27/2006
Citation: Jin, Z.T., Zhang, H.Q., Hermawan, N., Dantzer, W. 2006. Effects of treatment temperature and ph of liquid eggs on inactivation of salmonella and listeria by pulsed electric fields. IFT Annual Meeting, June 24-28, 2006, Orlando, FL. Paper No. 039K-15. Interpretive Summary:
Technical Abstract: Occurrences of egg-related outbreaks of Salmonella and awareness of the potential for Listeria contamination have heightened the concern for the safety of egg-related products. Application of pulsed electric fields (PEF) in liquid whole egg (LWE) or liquid egg white (LEW) pasteurization has been studied, but the reduction of pathogens was limited. The objective of this study was to investigate that change of egg’ pH or increase of treatment temperature would enhance the effectiveness of PEF treatment in inactivation of pathogens. S. typhimurium, S. enteritidis and L. monocytogenes cells were inoculated in LWE or LEW. The pH of samples was adjusted into pH 6.6, 7.2, or 8.2. The treatment temperature was 15C, 25C, 30C, or 40C. OSU-3C lab scale PEF machine was used. The PEF process conditions were field strength 25 kV/cm, pulse duration 2.1 micro sec, total treatment time 250 micro sec, pulse repetition = 200 pulse per second and flow rate = 1 mL/s. The non-treated (control) and treated samples were plated onto tryptic soy agar (S. typhimurium and S. enteritidis) or brain–heart infusion agar (L. monocytogenes) and incubated at 35C for 24 h. There was no apparent effect of treatment temperature (15C vs. 25C) on the inactivation of S. typhimurim, S. enteritidis and L. monocytogenes in LWE at pH6.6. S. typhimurim cells in LWE at pH 7.2 were reduced by 2.1 logs at 40C and 1.8 logs at 30C. 1.3 and 0.6 log reductions of S. typhimurim in LEW at pH 8.2 were obtained at 25C and 15C, respectively. The results showed that effects of treatment temperature in inactivation of pathogens were dependent on pH of liquid eggs, and increasing treatment temperature at neutral pH would enhance the effectiveness of PEF treatment. This study demonstrates an approach to increase efficiency of PEF in microbial reduction in liquid eggs.