Inactivation of Escherichia coli O157:H7 and Salmonella enteritidis in Liquid Egg White Using Pulsed Electric Field |
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| Authors: | Malek Amiali Michael O Ngadi James P Smith Vijaya G S Raghavan |
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| Affiliation: | Authors Amiali, Ngadi, and Raghavan are with Dept. of Bioresource Engineering, McGill Univ., Macdonald Campus, 21111 Lakeshore Rd., Ste-Anne-de-Bellevue, H9X3V9, Que., Canada. Author Smith is with Dept. of Food Science and Agriculture Chemistry, McGill Univ., Macdonald Campus, Ste-Anne-de-Bellevue, Que., Canada. Direct inquiries to author Ngadi (E-mail: ). |
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| Abstract: | ABSTRACT: The effects of temperature and pulsed electric field (PEF) intensity on inactivation of pathogens such as Escherichia coli O157:H7 and Salmonella enteritidis in egg white was investigated. Liquid egg white inoculated with 108 colony-forming units (CFU)/mL of each pathogen was treated with up to 60 pulses (each of 2 JAS width) at electric field intensities of 20 and 30 kV/cm. The processing temperatures were 10°C, 20°C, and 30°C. After treatment, uninjured and total viable cells were enumerated in selective and nonselective agars, respectively. Maximum inactivations of 3.7 and 2.9 log units were obtained for S. enteritidis and E. coli O157:H7, respectively, while injured cells accounted for 0.5 and 0.9 logs for E. coli O157:H7 and S. enteritidis , respectively. For both bacteria, increasing treatment temperature tended to increase the inactivation rate. There was synergy between electric field intensity and processing temperature. The inactivation rate constant k T values for E. coli O157:H7 on both selective and nonselective agars were 8.2 × 10-3 and 6.6 × 10-3/μS, whereas the values for S. enteritidis were 16.2 × 10-3 and 12.6 × 10-3/μS, respectively. The results suggest that E. coli O157:H7 was more resistant to heat-PEF treatment compared with S. enteritidis. |
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| Keywords: | liquid egg white E coli O157:H7 S enteritidis injured cells pulsed electric field |
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