| Summary: | The present study evaluated the presence of <i>Listeria</i> spp. and <i>L. monocytogenes</i> in four plants producing PDO Taleggio cheese. A total of 360 environmental samples were collected from different areas during production. The sampling points were identified as Food Contact Surfaces (FCS), transfer-Non Food Contact Surfaces (tr-NFCS), and non-transfer-NFCS (non-tr-NFCS). Fifty-nine ingredients/products were also analyzed. <i>Listeria</i> spp. was found in all the plants with a mean prevalence of 23.1%; plants that included a ripening area showed significantly higher prevalence if compared to the other plants. The positivity rate detected on FCS was moderate (~12%), but significantly lower if compared to NFCS (about 1/4 of the samples, <i>p</i> < 0.01). Among the FCS, higher prevalence was revealed on ripening equipment. <i>Listeria</i> spp. was never detected in the ingredients or products. A total of 125 <i>Listeria</i> spp. isolates were identified, mostly as <i>L. innocua</i> (almost 80%). <i>L. monocytogenes</i> was detected only from two FCS samples, in an area dedicated to the cutting of ripened blue cheeses; strain characterization by whole genome sequencing (WGS) evidenced a low virulence of the isolates. The results of the present study stress the importance of <i>Listeria</i> spp. management in the dairy plants producing PDO Taleggio and similar cheeses, mainly by the application of strict hygienic practices.
|
|---|