Division of Animal and Nutritional Sciences, West Virginia University, Morgantown, WV 26506, USA.
Division of Animal and Nutritional Sciences, West Virginia University, Morgantown, WV 26506, USA.
Poult Sci. 2022 Aug;101(8):101976. doi: 10.1016/j.psj.2022.101976. Epub 2022 May 26.
This study compares kinetic parameters of Salmonella and surrogate Enterococcus faecium in mash broiler feed during thermal inactivation. Two-gram samples of mash broiler feed were added into a filtered sample bag and inoculated with nalidixic acid (NaL, 200 ppm) resistant S. Typhimurium or Enterococcus faecium, followed by vacuum-packaging and heating in a circulated thermal water bath at 75°, 85°, and 95°C for 0 to 180 s. Counts of bacterial survival were analyzed on tryptic soy agar and bile esculin agar plus 200 ppm of NaL. Microbial data and thermal kinetic parameters (n = 8, Global-Fit and United States Department of Agriculture [USDA]-Integrated-Predictive-Modeling-Program software) were analyzed by JMP software. Heating mash broiler feed at 75°, 85°, and 95°C decreased (P < 0.05) Salmonella cell counts by >6 logCFU/g after 180, 60, and 50 s, respectively. Heating E. faecium in feed at 75°, 85°, and 95°C for 180, 120, and 70 s achieved reductions of 3, 6, and >6.5 logCFU/g, respectively. D-values of linear, Weibull models, and z-value of Salmonella at 75°, 85°, and 95°C were 1.8 to 11.2, 4.2 to 21.8, and 28.6 s, respectively, which were lower (P < 0.05) than those of E. faecium (3.7-18.1, 8.5-34.4, and 34.1 s). Linear with Tail, Linear with Tail and Shoulder, and Weibull with tail equations revealed that E. faecium were more resistant (P < 0.05) to heat than Salmonella as shown by longer "Shoulder-time" (26.5 vs. 16.2 s) and greater "Tail" effect (4.4-4.5 vs. 2.5-2.6 logCFU/g). Results clearly suggested that E. faecium can be used as a surrogate for Salmonella to validate thermal inactivation during feed manufacture.
本研究比较了沙门氏菌和替代粪肠球菌在肉鸡配合饲料中的热失活动力学参数。将 2 克肉鸡配合饲料样品加入过滤样品袋中，并用萘啶酸（NaL，200ppm）抗性鼠伤寒沙门氏菌或粪肠球菌进行接种，然后进行真空包装，并在循环热水浴中于 75°C、85°C 和 95°C 下加热 0 至 180s。在胰蛋白酶大豆琼脂和胆汁七叶苷琼脂上分析细菌存活数，并添加 200ppm 的 NaL。使用 JMP 软件分析微生物数据和热动力学参数（n=8，Global-Fit 和美国农业部[USDA]-综合预测建模程序软件）。在 75°C、85°C 和 95°C 下加热肉鸡配合饲料，沙门氏菌细胞数分别在 180、60 和 50s 后减少了>6 个对数 CFU/g（P<0.05）。在 75°C、85°C 和 95°C 下加热饲料中的粪肠球菌 180、120 和 70s 后，分别减少了 3、6 和>6.5 个对数 CFU/g。沙门氏菌在 75°C、85°C 和 95°C 下的 D 值、Weibull 模型和 z 值分别为 1.8 至 11.2、4.2 至 21.8 和 28.6s，均低于（P<0.05）粪肠球菌（3.7-18.1、8.5-34.4 和 34.1s）。线性带尾、线性带肩和带尾 Weibull 方程表明，粪肠球菌比沙门氏菌更能抵抗（P<0.05）热量，表现为更长的“肩时间”（26.5 比 16.2s）和更大的“尾”效应（4.4-4.5 比 2.5-2.6 个对数 CFU/g）。结果清楚地表明，粪肠球菌可用作沙门氏菌的替代品，以验证饲料生产过程中的热失活动力学。
