ARS | Publication request: Effect of cryogenic freezing on salmonella and listeria recovery from inoculated shrimp

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 23, 2011
Publication Date: July 31, 2011
Citation: Rajkowski, K.T., Bender, E. 2011. Effect of cryogenic freezing on salmonella and listeria recovery from inoculated shrimp. International Association for Food Protection.,Milwaukee, Wisconsin., 7-31 to 8-3-2011., Poster #: P3-76.

Technical Abstract: In the United States, shrimp is number one in seafood consumption. Shrimp is usually imported frozen, and the Food and Drug Administration has isolated Salmonella spp. from this frozen product. This research was conducted to determine the effect of two cryogenic freezing protocols (time and temperature) on the recovery of Salmonella and Listeria monocytogenes (LM) from inoculated shrimp, and the color and texture after freezing. Thawed shrimp were dipped in either a cocktail of Salmonella or LM to achieve a background level of 3 log. The inoculated shrimp were frozen at -175 deg F (-115 deg C) for either 3 or 5 minutes. Recovery of the Salmonella was done on XLT-4 and LM on Palcam after 2, 9 and 21 days frozen storage at -20 deg C. The Salmonella or LM recovered after 2 days storage was 1 log lower than the initial inoculation on the shrimp and this recovery level remained constant for the 9 and 21 day stored sample. Texture analysis comparing the treated (frozen) and untreated shrimp showed no texture difference. The color analysis of the treated (frozen) and untreated showed no visual change. The freezing protocols of -175 deg F (-115 deg C) for either 3 or 5 minutes had no effect on quality, whereas both cryogenic freezing times only slightly reduced the level of Salmonella or LM occurred.