Comparative study on the accuracy of three different pretreatment methods for the detection of total viable count in seasoned meat products
三种不同前处理方法对检测调理肉制品中菌落总数准确性的比较研究

摘要

目的 调理肉制品中的防腐剂、酸度调节剂等添加剂会抑制微生物生长，可能导致依据《GB4789.2-2022》的检测结果不准确。本研究比较三种前处理方法对调理肉制品菌落总数检测结果的影响，为建立更精准的检测方案提供依据。方法 以市售预调理黑椒风味鸡胸肉为对象，人工接种大肠埃希氏菌（Escherichiacoli）ATCC25922和金黄色葡萄球菌（Staphylococcusaureus）ATCC6538的混合菌悬液，分别采用国标法（方法A：无菌生理盐水均质）、国标法+中和剂法（方法B：含中和剂的稀释液均质）和均质洗涤离心法（方法C）处理，然后按GB4789.2-2022培养计数。结果 方法A的检测结果显著低于其他方法（P<0.05），回收率仅62.4%，菌落形态偏小且不均一。方法B回收率显著提升至89.7%，菌落形态饱满、大小均匀。方法C回收率最高（95.3%），但操作繁琐。结论 常规国标法用于调理肉制品易因添加剂抑制导致结果偏低。在样品均质时添加广谱中和剂（方法B）是一种高效、准确且实用的优化方法，推荐作为此类产品菌落总数检测的标准前处理。

Abstract

Objective Additives such as preservatives and acidity regulators in seasoned meat products may inhibit microbial growth, potentially leading to inaccurate test results based on 《GB 4789.2-2022》. This study aimed to compare the effects of three pretreatment methods on the detection results of total viable count (TVC) in seasoned meat products, providing a basis for establishing a more accurate detection protocol.
Methods Commercial pre-seasoned black pepper-flavored chicken breast was used as the test material. A mixed bacterial suspension of Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 6538 was artificially inoculated. Three pretreatment methods were applied: the national standard method (Method A: homogenization with sterile saline), the national standard method with neutralizer (Method B: homogenization with neutralizer-containing diluent), and the homogenization-washing-centrifugation method (Method C). Colony counting was performed according to 《GB 4789.2-2022》.
Results The detection result of Method A was significantly lower than those of the other two methods (P < 0.05), with a recovery rate of only 62.4% and colonies appearing smaller and uneven in size. Method B significantly improved the recovery rate to 89.7%, with colonies appearing plump and uniform in size. Method C achieved the highest recovery rate (95.3%), but the procedure was more cumbersome.
Conclusion   The conventional national standard method tends to yield underestimated results for seasoned meat products due to additive inhibition. Adding a broad-spectrum neutralizer during sample homogenization (Method B) is an efficient, accurate, and practical optimization strategy, recommended as the standard pretreatment method for TVC detection in such products.