P1-91 Effect of Thermal Processing on the Survival of Salmonella Species, L. monocytogenes, and E. coli O157:H7 during the Baking Process of Fruit-filled Grain Bars

Sunday, July 26, 2015
Exhibit Hall (Oregon Convention Center)
May Yeow , ConAgra Foods , Omaha , NE
Balasubrahmanyam Kottapalli , ConAgra Foods , Omaha , NE
Kelly Dawson , ConAgra Foods , Omaha , NE
Jordan Sabez
Edith Akins , ConAgra Foods , Omaha , NE
Steven Hermansky , ConAgra Foods, Inc. , Omaha , NE
Introduction: Recent recalls and outbreaks due to foodborne pathogens in thermally processed low moisture foods highlight the need for food industries to validate their thermal process. 

Purpose: The purpose of this study was to evaluate the thermal inactivation kinetics of Salmonella spp., L. monocytogenes, and E. coli O157:H7 during the baking processes of fruit-filled grain bars. 

Methods: Fruit-filled grain bar samples were obtained from an internal manufacturing facility. The samples were individually inoculated with cocktails of Salmonella spp., L. monocytogenes, and E. coli O157:H7 at the interface between the filling and the dough to achieve a target level of 108CFU/g. Following inoculation, samples were baked at oven settings of 300°F or 340°F for 9 min. The process parameters were chosen based on a worse-case scenario that is representative of the commercial processing conditions. Internal product temperatures were monitored and recorded during baking. Inoculated samples were enumerated using scientifically validated methods. All experiments included 3 replicates. Water activity analysis was also performed before and after baking. Log transformed data were analyzed using one-way ANOVA model with 95% prediction intervals to determine the minimum thermal processing parameters required to achieve a 4- or 5-log reduction of targeted pathogens.

Results: Statistical data analysis indicated that the internal product temperatures of 173.3°F and 189.9°F (for oven setting of 300°F and 350°F, respectively) at the end of 9 minutes baking process delivered a minimum 4- and 5-log reduction (P < 0.05), respectively, in Salmonella spp., L. monocytogenes, and E. coli O157:H7.

Significance: The study findings indicate that the thermal process employed by ConAgra Foods cereal bar manufacturing facility achieves an acceptable lethality of the vegetative pathogens evaluated in this study. The data also provide scientific basis to support the management of baking as an operational pre-requisite program (not a CCP) in the facility’s food safety plan.