Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/12/2006
Publication Date: 6/1/2007
Citation: Alvarez, I., Niemira, B.A., Fan, X., Sommers, C.H. 2007. Inactivation of Salmonella Enteriditis and Salmonella Senftenberg in liquid whole egg using generally recognized as safe additives, ionizing radiation and heat. Journal of Food Protection. 70(6):1402-1409. Interpretive Summary: Salmonella is an occasional contaminant in liquid whole egg (LWE) products that has been associated with foodborne illness outbreaks. Ionizing radiation, heat, or food additives can inhibit the growth of, or inactivate, Salmonella in LWE products. In this study it was determined that a low radiation dose of 0.3 or 1.0 kGy in combination with the food additive nisin (2.5 mg/liter)could reduce the heat treatment time needed to inactivate 99.999% of Salmonella in LWE from 5.5 min to 1.7 min at a temperature of 60C, which is typically used by processors in the U.S. LWE manufacturers could use this information to reduce heat treatment times or inactivate greater numbers of the Salmonella that occasionally contaminate LWE products.
Technical Abstract: The effect of combining irradiation followed by heat on Salmonella Enteriditis and Salmonella Senftenberg inoculated into liquid whole egg (LWE) with added nisin, EDTA, sorbic acid, carvacrol, or combinations of these GRAS additives was investigated. Synergistic reductions of Salmonella populations were observed when LWE containing GRAS additives was treated by gamma irradiation (0.3 and 1.0 kGy), heat (57 and 60C) or irradiation followed by heat. The presence of additives reduced the initial irradiation D-10 values by 1.2-1.5 fold, the thermal D-10 values by up to 3.5 and 1.8 fold at 57 and 60C, respectively, for both Salmonella serovars. For all the additives investigated, 2.5 mg/L nisin was most effective at reducing the treatment times needed to obtain a 5-log10 reduction of the Salmonella. Thus, while treatments of 21.6 min at 57C or 5 min at 60C, respectively should be applied to obtain a 5-log10 reduction of Salmonella in LWE, only 5.5 min or 2.3 min at 57C and 1.7 min at 60C after 0.3 or 1.0 kGy, respectively would be required if 2.5 mg/L nisin was used. The synergistic reduction of Salmonella viability by IR-H treatments in the presence of GRAS additives could enable producers to reduce the temperature of the process time of thermal treatments (in USA, 60C-3.5 min), or to increase the level of Salmonella inactivation.