ARS | Publication request: INACTIVATION OF SALMONELLA IN LIQUID WHOLE EGG BY IONIZING RADIATION AND HEAT

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: December 15, 2005
Publication Date: July 20, 2005
Citation: Alvarez, I., Niemira, B.A., Fan, X., Sommers, C.H. 2005. Inactivation of salmonella in liquid whole egg by ionizing radiation and heat. Institute of Food Technologists Annual Meeting and Food Expo, July 16-20, 2005, New Orleans, LA. p. 108-4.

Technical Abstract: Heat pasteurization is typically used by the food industry to assure the microbial safety of liquid whole egg (LWE). However, actual heat treatments do not provide more than 1-4 log10 cycles reduction of Salmonella serovars, and can cause changes in egg quality. Ionizing radiation (IR) is a safe and effective technology used to inactivate pathogens in food. However, the sensory and functional properties of eggs are relatively radiation sensitive. The use of thermal treatment and IR in combination may result in adequate reduction of Salmonella populations while simultaneously maintaining LWE quality. Our objective was to study the effect of IR, followed by heat, on different serovars of Salmonella suspended in LWE. Six strains of Salmonella (Anatum, Dublin, Enteritidis, Newport, Senftenberg and Typhimurium) were individually inoculated into LWE and irradiated to doses of 0 to 3 kGy (137-Cs self-contained gamma radiation source, 0.095 kGy/min, 4C), heat (55 to 60C), or combinations of IR followed by heat. Serovar Senftenberg was the most IR (D=0.65 kGy) and heat (D55C=11.36', z=4.9C) resistant Salmonella. The application of IR treatments as low as 0.1 kGy prior to thermal treatment reduced Salmonella serovar Senftenberg D55C and D60C values to 3.2' and 0.6', respectively. The reduction in thermal D value was independent of the IR dose applied. In the case of Salmonella serovar Enteritidis, IR pre-treatment reduced the D55C by 3 fold. IR, followed by application of thermal treatment, resulted in a synergistic reduction of Salmonella viability. This synergism could enable LWE producers to reduce the temperature or the process time of thermal treatments (in USA, 60C-3.5'; in UK, 64C-2.5'), or to increase the level of Salmonella inactivation. Thus 0.3 kGy IR followed by 60C-3.5' would reduce Salmonella serovar Senftenberg, and other Salmonella serovars such as Enteriditis, by at least 6 log10 cycles.