Sources and Risk Factors for Contamination, Survival, Persistence, and Heat Resistance of Salmonella in Low-Moisture Foods

Abstract

Sources and risk factors for contamination, survival, persistence, and heat resistance of Salmonella in low-moisture foods are reviewed. Processed products such as peanut butter, infant formula, chocolate, cereal products, and dried milk are characteristically low-water-activity foods and do not support growth of vegetative pathogens such as Salmonella. Significant food safety risk might occur when contamination takes place after a lethal processing step. Salmonella cross-contamination in low-moisture foods has been traced to factors such as poor sanitation practices, poor equipment design, and poor ingredient control. It is well recognized that Salmonella can survive for long periods in low-moisture food products. Although some die-off occurs in low-moisture foods during storage, the degree of reduction depends on factors such as storage temperature and product formulation. The heat resistance of Salmonella is affected by many factors, mostly by strain and serotypes tested, previous growth and storage conditions, the physical and chemical food composition, test media, and the media used to recover heat-damaged cells. Salmonella heat resistance generally increases with reducing moisture. Care must be taken when applying published D- and z-values to a specific food process. The product composition and heating medium and conditions should not be significantly different from the product and process parameters used by the processors.

Water quality and resource management in the dairy industry

“…Water is, therefore, also capable of introducing contamination into food if appropriate care is not taken. In 2006, a chocolate company located in the UK was affected by contamination of chocolate by Salmonella, reputedly from a leaking wastewater pipe in the production area (Podolak et al 2010).…”

ProP Is Required for the Survival of Desiccated Salmonella enterica Serovar Typhimurium Cells on a Stainless Steel Surface

“…almonella has the ability to survive under low-moisture conditions for extended times and is one of the main biological hazards for dry-food manufacturers (1). Salmonella has been shown to survive for 8 months in halva, for 10 weeks when desiccated on paper discs, and for 12 months in peanut-flavored candy, while storage at 4°C under desiccation on plastic has resulted in 100 weeks of survival (2)(3)(4)(5).…”

Survival and Heat Resistance of Salmonella enterica and Escherichia coli O157:H7 in Peanut Butter

“…This pathogen is capable of surviving extended starvation and desiccation stresses and has caused major disease outbreaks associated with foods of low water activity (a w ), such as peanut butter (a w , 0.3 to 0.5) (13). Several recent outbreaks of salmonellosis, including two linked to peanut butter in 2007 and 2008, have brought attention to the persistence of Salmonella in low-a w foods (2)(3)(4).…”

“…Peanut butter is produced from roasted peanuts with moisture content of Ͻ1% (a w , Ͻ0.3); the extremely low water activity in peanut butter precludes active growth of spoilage and pathogenic microorganisms (10). The stresses of starvation and desiccation encountered by S. enterica throughout peanut harvest and peanut butter production may induce stress response mechanisms for cross-protection against subsequent heat stress (13,14).…”