U.S. Department of Health and Human Services


Date of this Version


Document Type



Control of Salmonella and Other Bacterial Pathogens in Low-Moisture Foods, First Edition. Edited by Richard Podolak and Darryl G. Black.


U.S. government work.


The presence and survival of Salmonella in low water activity (aw) foods continues to pose a challenge for the food industry. Peer‐reviewed literature data on prevalence and levels of contamination of Salmonella in low water activity foods in the United States are limited. Available published data include those on: Salmonella contamination on nuts and peanuts (Calhoun et al., 2013), almonds (Danyluk et al., 2007; Bansal et al., 2010), pecans (Brar, Strawn, and Danyluk, 2016), and walnuts (Davidson et al., 2015); prevalence and levels of Salmonella on spices (Van Doren et al., 2013); as well as data on prevalence of Salmonella in animal feed (Li et al., 2012). On the other hand, data on survival and inactivation of Salmonella in low water activity foods have been collected extensively. Examples include Salmonella in a wide variety of nuts (Uesugi, Danyluk, and Harris, 2006; Uesugi and Harris, 2006; Danyluk et al., 2008; Beuchat and Mann, 2010, 2011; Abd, McCarthy, and Harris, 2012; Blessington, Mitcham, and Harris, 2012, 2014; Kimber et al., 2012; Beuchat et al., 2013b; Blessington et al., 2013a; Blessington et al., 2013b; Brar et al., 2015), whey protein (Santillana Farakos, Frank, and Schaffner, 2013), peanut butter (Ma et al., 2009; Lathrop, Taylor, and Schnepf, 2014; Li, Huang, and Chen, 2014), dry confectionary raw materials (Komitopoulou and Penaloza, 2009), spices (Keller et al., 2013), and several others as detailed in the reviews by FAO/WHO (2014), Beuchat et al. (2013a) and Podolak et al. (2010). In these studies, Salmonella is shown to be very resistant to desiccation and, once the cells are dry, have an increased resistance to heat. A high degree of variability is seen among studies, substrates, and the environmental conditions under which the experiments take place. Water activity is one critical factor in Salmonella inactivation and survival. Other influencing factors include the interaction between water and Salmonella cells and the effect of temperature, as well as the interaction between water and other components of the food matrix (e.g., sugars and fats). How these factors and interactions influence survival is still not well understood.