Low-moisture foods (LMF with water activity, a_w < 0.85) including pet foods and black pepper powder have consistently been associated with foodborne disease caused by Salmonella enterica. Increased heat resistance and prolonged survival at low-moisture conditions, however, remain major challenges to achieve effective inactivation of Salmonella in low-moisture foods. At low water activity (a_w) conditions, heat resistance of Salmonella is greatly enhanced when compared to high a_w conditions. This study aimed to quantify the effect of a_w on the heat resistance of Salmonella enterica in pet food pellets and black pepper powder. Pet food pellets were inoculated with two strains of heat resistant S. enterica and black pepper powder was inoculated with a 5-strain cocktail of Salmonella. Both inoculated food samples were equilibrated at 0.33, 0.54, and 0.75 a_w in controlled humidity chambers. Inoculated pet food pellets and black pepper powder in closed aluminum cells were heat treated at specific temperatures for selected times. The results showed that the Weibull model fitted well the inactivation data. At a specific temperature, the rate of inactivation increased with the increase in the a_w from 0.33 to 0.75, and the 3-log reduction times decreased for Salmonella in both food samples with the increase in a_w. Water adsorption isotherms of pet food pellets and black pepper powder at initial and treatment temperatures were developed to understand the change in a_w during heat treatments. The change in a_w during heat treatment was dependent on the type of food matrix, which possibly influenced the thermal inactivation of Salmonella in pet food pellets and black pepper powder. The quantitative analysis of heat reduction of Salmonella with respect to a_w aids in selection of the appropriate initial a_w to develop effective heat treatment protocols for adequate reduction of Salmonella in pet foods and black pepper powder.

 包括宠物食品和黑胡椒粉在内的低水分食品（LMF具有水活度，_w <0.85）一直与由肠沙门氏菌引起的食源性疾病相关。然而，提高耐热性和在低水分条件下延长生存期仍然是实现低水分食品中沙门氏菌有效灭活的主要挑战。在低水分活度（a _w）条件下，与高_{w w}条件相比，沙门氏菌的耐热性大大提高。这项研究旨在量化_w对肠炎沙门氏菌耐热性的影响在宠物食品颗粒和黑胡椒粉中。宠物食品颗粒接种有两株耐热的肠炎链球菌，黑胡椒粉接种有5株沙门氏菌。在受控湿度箱中，两种接种的食物样品均以0.33、0.54和0.75 a _w的平衡。将封闭的铝室中已接种的宠物食品颗粒和黑胡椒粉在特定温度下热处理选定的时间。结果表明，Weibull模型很好地拟合了失活数据。在特定温度下，失活的速率的增大而在一个增加的_瓦特从0.33至0.75，和3-log减少时间减少沙门氏菌两种食物样品中_w的增加。宠物食品颗粒和黑胡椒粉在初始和处理温度下的吸水等温线是为了了解热处理期间_w的变化而开发的。热处理过程中_w的变化取决于食物基质的类型，这可能会影响宠物食物颗粒和黑胡椒粉中沙门氏菌的热失活。沙门氏菌相对于_w的热还原的定量分析有助于选择合适的初始_w来开发有效的热处理方案以充分减少沙门氏菌 在宠物食品和黑胡椒粉中。