Foodborne pathogens such as Salmonella can endure dry environments of milk powders for extended periods due to the increased adaptability at a low water activity (a_w) and proliferate when powders are hydrated. This study compared the survivability and the thermal resistance of a 5-serovar Salmonella cocktail in dry and hydrated nonfat dry milk (NFDM) and whole milk powder (WMP) stored for 180 days at ambient temperature (~20 °C). This study was designed as two factorial (storage days and milk powder type) randomized complete block design with three replications as blocks. The milk powders were spray inoculated with 5-serovar Salmonella cocktail and dried back to the original pre-inoculation a_w. The D-values of Salmonella in inoculated NFDM and WMP were determined periodically (every 30 days, starting from day one). The milk powders were also individually hydrated on each analysis day to determine D- and z-values of Salmonella in hydrated powders. The D-values were determined using thermal-death-time disks and hot-water baths at 80, 85 and 90 °C for milk powders, and 59, 62 and 65 °C for hydrated powders. The D- and z-values of Salmonella at specific temperatures within dry or hydrated powders during the storage period were compared at P ≤ 0.05 using two-way ANOVA and Tukey's Test. The D-values of Salmonella in WMP on day 1 were 18.9, 9.9 and 4.4 min at 80, 85 and 90 °C, respectively, which increased to 29.4, 13.6 and 6.5 min at 80, 85 and 90 °C, respectively, on day 180. Whereas, D-values of Salmonella in NFDM on day 1 were 17.9, 9.2 and 4.4 min at 80, 85 and 90 °C, respectively, and stayed similar during the storage. The D-values of Salmonella in milk powder remained similar throughout the storage once hydrated. The overall z-value of Salmonella in NFDM and WMP was 16.3 °C, whereas in hydrated NFDM and WMP, the overall z-value was 6.4 °C.

食源性病原体（如沙门氏菌）可在低水分活度（a _w）下提高适应性，从而在奶粉的干燥环境中长期忍受，并在奶粉水合时扩散。这项研究比较了5-血清沙门氏菌鸡尾酒在干燥和水合脱脂干奶（NFDM）和全脂奶粉（WMP）中于环境温度（〜20°C）下储存180天的生存能力和耐热性。本研究被设计为两个因子分解（存储天数和奶粉类型）随机完整块设计，其中三个重复作为块。牛奶粉末喷雾接种5血清型沙门氏菌鸡尾酒，干燥回原始预接种一_瓦特。定期（从第一天开始每隔30天）确定接种NFDM和WMP中沙门氏菌的D值。在每个分析日还将奶粉分别水合，以测定水合粉中沙门氏菌的D值和Z值。D值是使用热死亡时间盘和热水浴在80、85和90°C下对奶粉确定的，在59、62和65°C下对水合粉末进行测定的。D-和的z值沙门氏菌在干燥或水合的粉末内的特定的温度下在储存期间物在比较P 使用双向ANOVA和Tukey检验≤0.05。沙门氏菌的D值在WMP中，第1天在80、85和90°C分别为18.9、9.9和4.4分钟，而在第180天在80、85和90°C分别上升到29.4、13.6和6.5分钟。在第1天，NFDM中沙门氏菌的值分别在80、85和90°C下分别为17.9、9.2和4.4分钟，并且在存储过程中保持相似。奶粉中沙门氏菌的D值一旦水化，在整个存储过程中都保持相似。NFDM和WMP中沙门氏菌的总z值为16.3°C，而水合NFDM和WMP中沙门氏菌的总z值为6.4°C。