Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/2/2011
Publication Date: 8/2/2011
Citation: Gurtler, J., Marks, H.M., Jones, D.R., Bailey, R. 2011. Thermal inactivation kinetics of Salmonella Enteritidis and Oranienberg in commercially acquired 10% salted liquid whole egg [abstract]. IAFP 100th Annual meeting, July 31-August 3, 2011, Milwaukee, Wisconsin. 1:1.
Technical Abstract: Liquid egg pasteurization requirements are based on time/temperature combinations in the Code of Federal Regulations, Title 9, Ch. III, Sec. 590.570 from data acquired prior to 1970. These guidelines are being reevaluated in light of recent risk assessments. Heat-resistant Salmonella Enteritidis and Oranienburg were grown in Tryptic Soy broth at 37 deg C, composited and added to 10% salted LWE and mixed, resulting in final populations of ca. 5.7-7.8 log CFU/ml. Inoculated egg was injected into glass capillary tubes, flame-sealed and heated in a water bath at 60, 62.2, 63.3 64.3 or 66 deg C. Contents were surface plated, incubated at 37 deg C for 24 h, and colonies were enumerated. Random presumptive positive colonies were confirmed by selective differential plating and serological agglutination. Results: Survival curves were not log-linear (log levels versus time), but decreased rapidly, and after initial periods became linear. Asymptotic decimal reduction values at each temperature were calculated from survivor curves with a minimum inactivation of 5.0 log CFU/ml. The asymptotic thermal D-values for salted LWE were 3.05, 1.70, 1.25, 1.00 and 0.63 min at 60, 62.2, 63.3 64.3 or 66 deg C, respectively. The calculated thermal z-value was 8.8 deg C. A model that predicts lethality for given times and temperatures was developed. The D- and z-values reported in our study are similar to those reported in the literature and confirm that the current pasteurization requirements for 10% salted LWE of minimum temperatures, times of 63.3 deg C for 3.5 min, or 62.2 deg C for 6.2 min, are not sufficient to inactivate 7 log CFU/ml of Salmonella and are estimated to provide ca. 4 – 5 log CFU/ml of destruction. This model will assist the USDA, FSIS in issuing pasteurization performance standards and provide industry guidance for designing pasteurization processes that will ensure safe product.