Title: Impact of chlorine, temperature and freezing shock on the growth behavior of Escherichia coli O157:H7 on ready-to-eat meats Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 10, 2011
Publication Date: June 10, 2011
Citation: Sheen, S., Hwang, C., Juneja, V.K. 2011. Impact of chlorine, temperature and freezing shock on the growth behavior of Escherichia coli O157:H7 on ready-to-eat meats. Meeting Abstract. Annual International Association of Food Protection,Pg 1, July 31 thru August 3, 2011, Milwaukee, Wisconsin. Technical Abstract: Foodborne pathogens continue to pose potential food safety hazard in ready-to-eat (RTE) meat. Chlorine is commonly used to sanitize processing equipment where Escherichia coli O157:H7 (Ec) may survive and contaminate food products. The objective of this study was to characterize the behavior of chlorine-exposed Ec on RTE meats. A 4-strain cocktail of Ec was pre-treated with chlorine (0, 25, and 50 ppm) for two hours, and then inoculated onto RTE meat surfaces to obtain about 3.0 log CFU/g. Samples were stored at three temperatures (12, 18, and 24 deg C) and Ec was enumerated during the storage. The freezing shock impact was studied using the chlorine-treated Ec after stored the Ec in a freezer overnight. The lag phase and growth rate of Ec were estimated using DMFit (Combase, Baranyi’s model). Results indicated that Ec growth was supressed by chlorine treatment. The freezing was found to have no impact at 25 ppm and a ‘negative’ effect (slightly promoting growth) at 50 ppm. The lag phase of Ec after exposure to 0 ppm of chlorine (50.3 hrs) was shorter than that of Ec treated with 25 ppm (54.6 hrs) and 50 ppm (164.1 hrs) at 12 deg C. However, the lag phase decreased with an increase in temperature. For example, at 25 ppm, lag times were 54.6, 51.1 and 48.9 hours for 12, 18 and 24 deg C, respectively. Lag times increased with an increase in chlorine concentration. At 24 deg C, lag times were 15.8, 48.9, and 52.4 hours for 0, 25, and 50 ppm, respectively. The growth rate increased with an increase in temperature for 0 and 25 ppm chlorine levels, but decreased at 50 ppm level. Growth rate and lag phase as a function of temperature and chlorine concentration can be described by polynomial models (linear regression). Results of this study will contribute to risk assessment of RTE meats.