1 U.S. Department of Agriculture, Agricultural Research Service, Roman L. Hruska U.S. Meat Animal Research Center, P.O. Box 166, Clay Center, Nebraska 68933-0166 (ORCID: http://orcid.org/0000-0001-9035-0474 [T.M.A.] and http://orcid.org/000-0003-0494-2436 [J.W.S.]).
2 Cargill Meat Solutions, 151 North Main Street, Wichita, Kansas 67202, USA.
J Food Prot. 2018 Jul;81(7):1126-1133. doi: 10.4315/0362-028X.JFP-17-469.
The U.S. beef industry must provide documentation to the U.S. Department of Agriculture, Food Safety and Inspection Service (USDA-FSIS) that the antimicrobial interventions implemented or any subsequent changes in the process are effective under the actual conditions that apply in its operation. The main objective of this study was to determine whether surface pH after application of diluted lactic acid solution on surfaces of fresh meat can be used as a control measure indicator for the reduction of E. coli O157:H7 and Salmonella. Samples (240 each) of lean and adipose beef tissues were inoculated with cocktail mixtures of Escherichia coli O157:H7 and Salmonella. Application parameters were varied such that lean and adipose tissues were spray treated with either 2 or 4.5% lactic acid solution at either 38 or 60°C for 1 to 10 s. Lean and adipose tissues were collected before and after spray treatments for enumeration of the pathogens. Based on the conditions of this study, there was no difference between spray treatments at 38 or 60°C, but 4.5% lactic acid solution reduced pathogens more effectively ( P ≤ 0.05) than did 2% lactic acid solution. Spray treatment with lactic acid solution for 1 to 10 s reduced surface pH values of lean tissues (3 to 3.8) and adipose tissues (2.75 to 3.65). At surface pH values of 3.0 and 2.75, lactic acid reduced E. coli O157:H7 on surfaces of lean and adipose tissues by approximately 1.60 and 1.54 log CFU/cm, respectively. At surface pH values of 3.8 and 3.65, lactic acid reduced E. coli O157:H7 on lean and adipose tissues by approximately 0.3 and 0.42 log CFU/cm, respectively. The surface pH values after lactic acid treatment and the reductions of both pathogens showed a strong linear relationship; this indicates that a surface pH of 3.1 would provide at least 1-log reduction of E. coli O157:H7 and Salmonella, regardless of lactic acid application parameters. Therefore, surface pH after spray treatment with lactic acid could be used to validate pathogen reduction.
美国牛肉行业必须向美国农业部食品安全检验局（USDA-FSIS）提供文件，证明实施的抗菌干预措施或随后对工艺的任何更改在其操作中适用的实际条件下是有效的。本研究的主要目的是确定在新鲜肉表面应用稀释乳酸溶液后表面 pH 是否可用作减少大肠杆菌 O157:H7 和沙门氏菌的控制措施指标。将鸡尾酒混合物大肠杆菌 O157:H7 和沙门氏菌接种到 240 份瘦组织和脂肪组织样本中。改变应用参数，使瘦组织和脂肪组织用 2%或 4.5%的乳酸溶液在 38 或 60°C 下喷雾处理 1 到 10 秒。在喷雾处理前后采集瘦组织和脂肪组织样本，以对病原体进行计数。根据本研究的条件，38°C 或 60°C 下的喷雾处理没有差异，但 4.5%的乳酸溶液比 2%的乳酸溶液更有效地减少病原体（P≤0.05）。乳酸溶液喷雾处理 1 到 10 秒可降低瘦组织（3 到 3.8）和脂肪组织（2.75 到 3.65）的表面 pH 值。在表面 pH 值为 3.0 和 2.75 时，乳酸分别将大肠杆菌 O157:H7 减少到瘦组织和脂肪组织表面的约 1.60 和 1.54 log CFU/cm。在表面 pH 值为 3.8 和 3.65 时，乳酸分别将大肠杆菌 O157:H7 减少到瘦组织和脂肪组织表面的约 0.3 和 0.42 log CFU/cm。乳酸处理后的表面 pH 值和两种病原体的减少呈强线性关系；这表明表面 pH 值为 3.1 将至少提供大肠杆菌 O157:H7 和沙门氏菌的 1 对数减少，而与乳酸应用参数无关。因此，乳酸喷雾处理后的表面 pH 值可用于验证病原体减少。
