PROCESSING INTERVENTION TECHNOLOGIES FOR ENHANCING THE SAFETY AND SECURITY OF FLUID FOODS AND BEVERAGES
Location: Food Safety and Intervention Technologies
Title: Survival of Yersinia in whole liquid egg as influenced by the presence of nisin
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 12, 2008
Publication Date: August 4, 2008
Citation: Gurtler, J., Zhang, H., Sommers, C., 2008. Survival of Yersinia in whole liquid egg as influenced by the presence of nisin. [abstract]. International Association for Food Protection - 95th Annual Meeting. p. 1.
Yersinia is a psychrotrophic, gram-negative bacterium capable of causing foodborne illnesses. The bacteriocin nisin, traditionally used to inhibit gram-positive bacteria, may be bacteriostatic to gram-negative bacteria under certain conditions. Nisin may be used at levels of up to 15 microgram/g in the processing of liquid egg products in the United States, although its influence on the survival of Yersinia in liquid egg is unknown. A study was conducted to determine the effects of nisin on the survival of Yersinia in whole liquid egg (WLE) stored at refrigerated and abused temperatures. Four strains of Yersinia were inoculated into WLE at a population of ca. 4.40 log CFU/ml and acclimated for two hours before the addition of nisin at concentrations of 0, 15, 150 and 500 IU/ml, stored at 4, 10, and 21C, and sampled at hours 0, 24, 48, and 72. Data from three experimental replications were pooled and statistically evaluated. There were no significant differences (P > 0.05) in populations of Yersinia in WLE based on variations in nisin concentration. Populations stored at 4C increased significantly during each consecutive sampling time at hours 24 and 48 (4.79 and 4.96 log CFU/ml), but not at hour 72 (5.01 log CFU/ml). Yersinia populations increased significantly at each sampling time when stored at 10C, from 4.43 log CFU/ml (hour 0) to 5.15, 5.94 and 6.60 log CFU/ml at 24, 48, and 72 hours, respectively. When WLE was stored at 21C, Yersinia increased to 5.51 and 8.70 log CFU/ml at 24 and 48 hours of storage, respectively, although populations declined to 8.29 log CFU/ml by hour 72. These results indicate that the presence of nisin at concentrations up to 500 IU/ml does not influence the growth or survival of Yersinia in WLE stored at 4, 10, or 21C for up to 72 hours.