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New Infrared Pasteurization Process Kills Listeria

By Pritzker | Ruohonen

With the outbreak of Listeria monocytogenes in pasteurized milk products from Whittier Farms looming over the food safety world, a new study suggests safer and more effective ways of killing the bacteria during the pasteurization process.  A study conducted by L. Huang and J. Sites published in the Journal of Food Science showed the effective elimination of Listeria from hotdogs with a new infrared pasteurization process.

The study was directly aimed at ready-to-eat meats such as hotdogs in order to kill Listeria on the surface of the meats.  The process utilized an infrared emitter, a hotdog roller, an infrared sensor, and a temperature controller. The sensor monitored the surface temperature of the hotdogs while the emitter was the heating source.

According to the article:

The infrared surface pasteurization was evaluated using hotdogs that were surface-inoculated with a 4-strain L. monocytogenes cocktail to an average initial inoculum of 7.32 log (CFU/g). On the average 1.0, 2.1, 3.0, or 5.3 log-reduction in L. monocytogenes was observed after the surface temperature of hotdogs was increased to 70, 75, 80, or 85 °C, respectively. Holding the sample temperature led to additional bacterial inactivation. With a 3 min holding at 80 °C or 2 min at 85 °C, a total of 6.4 or 6.7 logs of L. monocytogenes were inactivated.

The infrared pasteurization was successful in killing the bacteria that contaminated the surface of the hotdogs. Since the Whittier outbreak has shaken consumer confidence in the pasteurization process, it is good to see that pasteurization procedures are being reevaluated to provide a safer food source.  (We are aware that the Listeria contamination at Whittier Farms most likely happened post pasteurization.  Even so, the outbreak suggests the need to review pasteurization procedures.)

Full post as published by Food Poisoning Law Blog on January 23, 2008 (boomark / email).