Influence of Traditional Brine Washing of Smear Taleggio Cheese on the Surface Spreading of Listeria innocua

Abstract

The influence of a traditional procedure of washing of smear Taleggio cheese on surface spreading of Listeria innocua was studied. This practice is carried out during ripening to remove molds, to select the surface microflora, and to control the ripening process. One cheese, both of 2 (i) and 4 (ii) weeks of ripening, was surface-inoculated with approximately 3 log CFU of L. innocua per entire cheese surface. The inoculated cheeses and others of the same age were weekly washed with brine solution. Listeria was spread both on the surface of the inoculated cheese and on the other cheeses, and it was also found in the brines and on the wooden boxes where the cheeses were ripened. The time of ripening when contamination occurs influenced the behavior of Listeria. At the moment of contamination, the smear surface microflora of (i) cheese was approximately 2 log CFU/g higher than of (ii) cheese. Listeria inoculated on 2-week-ripened cheese was able to colonize the entire surface of the cheese and to cross-contaminate the other cheeses. On the contrary, Listeria inoculated on a 4-week-ripened cheese was partially spread on the surface of the originally inoculated cheese, and the transfer of contamination by the washing procedure was restrained. Because a random distribution of Listeria on cheese surface was observed, the importance of the mode of sampling was discussed. Because of the lack of critical control points during ripening of Taleggio cheese, the Listeria hazard needs to be controlled by taking appropriate control measures to break off the contamination cycle (cheese --> brine --> wooden boxes --> cheese).

Inhibition of Listeria monocytogenes by resident biofilms present on wooden shelves used for cheese ripening

“…Our observations are in agreement with previously published papers (Carminati, Neviani, Ottogalli, & Giraffa, 1999;Carminati et al, 2000) reporting that the presence of abundant and complex microbial flora on a cheese surface might help to control L. monocytogenes contamination of the cheese.…”

“…One wooden shelf was contaminated with L. monocytogenes out of the five analysed. Carminati, Perrone, Neviani, and Mucchetti (2000) showed that when cheese were inoculated with L. monocytogenes at the beginning of the ripening process, two out of the four analysed shelves were contaminated with the pathogen. By contrast, when cheeses were inoculated in the middle of the ripening process, no pathogens were detected on the wood surfaces.…”

Attenuated Lactococcus lactis and Surface Bacteria as Tools for Conditioning the Microbiota and Driving the Ripening of Semisoft Caciotta Cheese

“…Specifically, washing of the cheese surface was performed using a cotton cloth (one for each cheese variant) soaked in brine (43). For each batch, cheese sampling was performed at 1, 10, 20, and 30 days of ripening.…”

Identification of Microbiota Present on the Surface of Taleggio Cheese Using PCR–DGGE and RAPD–PCR

“…Furthermore, 13 commercial Taleggio PDO cheeses (T1 to T13) made in different dairies were purchased in retail outlets. All cheeses were produced according to the same manufacturing protocol and the best practices indicated by the Consortium of Taleggio (Gobbetti and others 1997; Carminati and others 2000, http://www.Taleggio.it). …”