P3-01 Fate of Salmonella and Escherichia coli O157:H7 in Cookie Dough during Storage: Comparison of Isolates from Different Origins

Wednesday, July 12, 2017
Exhibit Hall (Tampa Convention Center)
Shuang Wu , University of Florida , Gainesville , FL
Shelli Laskowitz , University of Florida , Gainesville , FL
Soohyoun Ahn , University of Florida , Gainesville , FL
Introduction: Cookie dough is recognized as a potential vehicle for Escherichia coli O157:H7 transmission after the multistate outbreak in 2009. It may also be contaminated with Salmonella for using egg as one of its ingredients. Although cookie dough has been associated with pathogens, consumers’ behavior of consuming raw cookie dough is still frequently reported. The pathogens’ survival in cookie dough during storage can cause foodborne illness and has not been fully studied.

Purpose: In this study, we compared the survival of Salmonella and E. coli O157:H7 isolates from different origins in commercial cookie dough.

Methods: Cookie dough samples were divided into six groups and inoculated with approximately 6.0 log CFU/g of Salmonella isolated from peanut outbreak, egg contaminate, and clinical samples, and E. coli O157:H7 isolated from cookie dough outbreak, salami, and environmental samples, separately. Cell count of each isolate was obtained during eight weeks of storage at 4°C.

Results: Overall, 0.84 to 1.30 log CFU/g reduction and 0.48 to 0.87 log CFU/g reduction was observed for Salmonella and E. coli O157:H7 in cookie dough during eight weeks of storage, respectively. Notably, Salmonella Tennessee isolate from peanut outbreak had much lower viable cell count than Salmonella Enteritidis isolates from eggs and clinical samples (P<0.05) after five days observation. Also, E. coli O157:H7 isolate from the cookie dough outbreak had a significantly lower number of viable cells than other E. coli O157:H7 isolates from salami and environmental samples (P<0.05) during eight weeks storage.

Significance: Our data suggests that Salmonella and E. coli O157:H7, once introduced, remain viable in cookie dough for at least two months. The survival of pathogens is affected by the origins of the isolates. Understanding the factors contributing to such phenomenon will be essential for the control of these pathogens in cookie dough.