Assessment of the Effect of Ingredients on Pathogen Survival in Cookie Dough

Introduction: Cookie dough is often recognized as a potential vehicle for Salmonella. Food Safety concern for cookie dough has been further raised due to the recent E. coli O157: H7 outbreak associated with commercial product. It is believed that the nature of cookie dough of high fat and sugar contents and relatively low water activity can provide protection for pathogens to survive during storage.

Purpose: The goal of this study was to determine the survival of foodborne pathogens in cookie dough and assess the impact of common cookie dough ingredients on survival of pathogens.

Methods: Commercial cookie dough was inoculated with Salmonella Enteritidis and E. coli O157:H7 (10⁶ CFU/g), stored at 4°C and -18°C, and the survival of pathogens was determined for 8 weeks. To determine the effect of ingredients on pathogen survival, cookie dough samples were prepared with various fat, sugar and salt contents, inoculated with Salmonella  Enteritidis or E. coli O157:H7 (10⁶ CFU/g), and their survival was determined for 8 weeks.

Results: After 8 weeks, 2.42 and 2.35 log reduction for Salmonella and 2.23 and 1.99 log reduction for E. coli O157:H7 were obtained for commercial cookie dough at 4°C and -18°C, respectively. Cookie dough prepared with seven different recipes of cookie resulted in reduction of both pathogens, ranging from 0.73 to 1.45 log CFU/g. Our results indicate that pathogens in cookie dough products can survive through their recommended storage conditions, and changing the content of a single ingredient hardly affects their survival rate.

Significance: Our study suggests that that refrigeration/freezing and monitoring the ingredients concentration do not reduce the survival of pathogens. Following good manufacturing practices is a fundamental step to eliminate initial introduction of pathogens in cookie dough, and, consumer education on risk of consuming raw cookie dough would be critical to eliminate future outbreaks.