Control of Surrogate Escherichia coli Populations in Three Food Products Using Common Food Service Cooling Methods

The United States Food and Drug Administration (U.S. FDA) has identified improper (“slow”) cooling as an important contributing factor in foodborne illness outbreaks. The efficacy of post-thermal treatment cooling techniques on controlling surrogate Escherichia coli growth in taco meat, chili con carne with beans, and low-sodium marinara sauce was evaluated. Each product was cooked to 73.9°C, portioned to 2- and 3-inch depths in stainless steel steam table pans, and cooled to 60°C ± 5°C before inoculation with E. coli. Pans were prepared with different cover methods to allow or restrict air exposure and then placed inside a -20°C commercial walk-in freezer or situated in ice water baths inside a 4°C commercial walk-in refrigerator. Product temperatures were recorded for 24 hours. Microbial populations were enumerated at 0, 4, 8, 12, and 24 hours. Temperature data for taco meat and chili con carne with beans revealed that few cooling methods met the 2017 FDA Food Code cooling criteria, while data for low-sodium marinara sauce showed that no cooling method met the Food Code chilling criteria. Population changes were < 0.50 log10 CFU/g over 24 hours in all products, indicating that all cooling methods were low risk for microbial proliferation and were therefore effective at controlling E. coli within these products.