Agricultural Bioprocess Laboratory, Food Science and Human Nutrition Department, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
(ORCID: https://orcid.org/0000-0003-2712-0793 [M.J.S.]).
J Food Prot. 2021 May 1;84(5):802-810. doi: 10.4315/JFP-20-435.
Ready-to-eat meat products, such as deli ham, can support the growth of Listeria monocytogenes (LM), which can cause severe illness in immunocompromised individuals. The objectives of this study were to validate a miniature ham model (MHM) against the ham slice method and to screen antimicrobial combinations to control LM on ham by using response surface methology (RSM) as a time- and cost-effective high-throughput screening tool. The effect of nisin (Ni), potassium lactate and sodium diacetate, lauric arginate (LAG), lytic bacteriophage (P100), and ε-polylysine (EPL) added alone, or in combination, were determined on the MHM over 12 days of storage. Results showed the MHM accurately mimics the ham slice method because no statistical differences were found (P = 0.526) in the change of LM cell counts in MHM and slice counts after 12 days of storage at 4°C for treated and untreated hams. The MHM was then used to screen antimicrobial combinations by using an on-face design and three center points in a central composite design. The RSM was tested by using a cocktail of five LM strains isolated from foodborne disease outbreaks. Three levels of the previously mentioned antimicrobials were used in combination for a total of 28 runs performed in triplicate. The change of LM cell counts were determined after 12 days of storage at 4°C. All tested antimicrobials were effective on reducing LM cell counts on ham when added alone. A significant antagonistic interaction (P = 0.002) was identified by the RSM between LAG and P100, where this antimicrobial combination caused a 2.2-log CFU/g change of LM cell counts after 12 days of storage. Two interactions, between Ni and EPL (P = 0.058), and Ni and P100 (P = 0.068), showed possible synergistic effects against LM on the MHM. Other interactions were clearly nonsignificant, suggesting additive effects. In future work, the developed MHM in combination with RSM can be used as a high-throughput method to analyze novel antimicrobial treatments against LM.
即食肉类产品，如熟食火腿，可以支持单增李斯特菌（LM）的生长，而 LM 可能会使免疫功能低下的个体患上严重疾病。本研究的目的是通过响应面法（RSM）作为一种省时、高效的高通量筛选工具，验证微型火腿模型（MHM）与火腿切片法的相关性，并筛选出控制火腿中 LM 的抗菌组合。单独或组合添加乳链菌肽（Ni）、乳酸钾和双乙酸钠、精氨酸月桂酯（LAG）、溶菌噬菌体（P100）和 ε-聚赖氨酸（EPL）对 MHM 的影响在 12 天的储存过程中进行了测定。结果表明，MHM 可以准确模拟火腿切片法，因为在 4°C 下储存 12 天后，处理和未处理火腿的 MHM 和切片 LM 细胞计数的变化没有统计学差异（P = 0.526）。然后，通过使用中心复合设计中的面设计和三个中心点，使用 MHM 筛选抗菌组合。通过使用从食源性疾病暴发中分离的五种 LM 菌株的鸡尾酒测试了 RSM。使用之前提到的三种抗菌剂的三个水平进行了总共 28 次重复的三次运行。在 4°C 下储存 12 天后，确定 LM 细胞计数的变化。单独添加时，所有测试的抗菌剂都能有效降低火腿上的 LM 细胞计数。RSM 确定 LAG 和 P100 之间存在显著的拮抗相互作用（P = 0.002），这种抗菌组合在 12 天的储存后导致 LM 细胞计数发生 2.2-log CFU/g 的变化。RSM 还显示 Ni 和 EPL 之间（P = 0.058）和 Ni 和 P100 之间（P = 0.068）的两种相互作用可能对 MHM 上的 LM 具有协同作用。其他相互作用显然不显著，表明具有相加作用。在未来的工作中，开发的 MHM 与 RSM 结合使用，可以作为一种高通量方法，分析针对 LM 的新型抗菌处理。
