Improving the methodology for Listeria monocytogenes detection in smoked salmon by using the wet pooling test

Controlling Listeria monocytogenes in smoked salmon is still a challenge for food business operators. The reported low levels and uneven distribution of the pathogen make it necessary to apply good sampling plans and analytical procedures in order to detect contaminated batches. However, analyses are expensive and due to current economic situations, usually only one sample per lot is checked instead of the n = 5 samples established in Regulation (EC) No 2073/2005. This work proposes the investigation of L. monocytogenes by pooling pre-enriched Half Fraser from several units from a batch (n = 6). The results obtained from a preliminary in-house validation (n = 51 pools) showed that the performance characteristics (sensitivity and specificity) are very high (> 95%). This high reliability, together with reduced costs (nearly half), suggests that the wet pooling test could be a good cost-effective approach for investigating L. monocytogenes in smoked salmon. Additional research is needed before this approach can be used for other food matrices, such as determining the maximum number of units per batch that can be pooled with effective detection of L. monocytogenes.