Implications of potential reduction of 100 cfug limit to LOQ (10 or 20 cfu/g)
CFA data (see Table 3 below) indicates that >99.99% of its members‘ 1,050,585 RTE food samples over the period 2011-2022 had unquantifiable L. monocytogenes even at the end of life, i.e. <20 cfu/g. This is the result of best practice implementation, working with the aim of L. monocytogenes being so well controlled that it is “Not Detected“. Best practice is to use a well-designed and thorough sampling programme continuously monitoring food and environment to assure controls’ efficacy and acting swiftly to effectively address detections. This best practice approach not only applies to L. monocytogenes but also to other Listeria species.
This approach is however not standard particularly among SMEs and FBOs not supplying own label to major UK multiples.
It should be noted that use of 10 cfu/g as LOD doubles the plating cost of methods, making it likely to reduce the amount of sampling done by FBOs given fixed budgets.
In previous discussion with UK Government agencies on potential consequences of 10 or 20/g as a limit for L. monocytogenes in RTE foods FSA’s analysis of CFA‘s headline data showed that there would be no public health benefit in reducing the 100 cfu/g limit since counts occur so rarely when best practice is in place.
Emphasis should therefore be on implementing best practice controls and monitoring (see Principles of an environmental monitoring programme for Lm) in RTE food production and storage including for sale, particularly where such foods are sold unpackaged or are directly handled (e.g. sliced) prior to packaging or consumption.
Table 3. Chilled Food Association Data: Listeria monocytogenes sampling by UK chilled prepared food producers 2011-2022
| RTE food prevalence (1,050,585 samples) | ~0.6% Lm at any point during shelf life, of which |
| ~0.01% with Lm present at quantifiable levels, i.e. >20 cfu/g LOQ | |
| Production environment prevalence (1,947,956 samples) | Food contact surfaces ~0.3% Lm (~964k samples) |
| Non-Food contact surfaces ~2.5% Lm (~984k samples) |
Source: Chilled Food Association
Edited 8 August 2023