Listeria monocytogenes in Gorgonzola: subtypes, diversity and persistence over time.

L. monocytogenes represents a primary concern in the production of Gorgonzola, a Protected Designation of Origin (PDO) Italian blue-veined cheese produced only in the Piedmont and Lombardy regions. L. monocytogenes isolates (N=95) obtained from Gorgonzola rinds, paste, and production/ripening environments were serotyped and then genotyped using Pulsed Field Gel Electrophoresis (PFGE). The goal of this study was to investigate the variability of L. monocytogenes PFGE-types across different PDO Gorgonzola manufacturers (N=22). The majority of the strains (88%) were serotyped as 1/2a. PFGE identified 2 major pulse-types grouping 62 strains, detected from different plants and years, suggesting the presence of persistent and niche-adapted L. monocytogenes. In 9 plants, environmental strains shared the same pulse-types with strains from rinds or paste, suggesting a possible transmission pathway. Encouragingly, L. monocytogenes was retrieved from only 1 paste, indicating that production processes were under control in 21 plants. In the remaining plant, un-effective pasteurization or cross-contamination during production processes could be the cause of the contamination. Consequently, it is imperative that producers operate under the total respect of the Good Manufacturing Practices and following the principles of the Hazard Analysis Critical Control Point plans, in order to contain contamination throughout the whole processing.

Undeclared allergenic ingredients in foods from animal origin: survey of an Italian region's food market, 2007-2009.

Several EC Directives have been promulgated to protect allergic individuals but no rule has been established with regard to allergen cross-contamination caused by shared transport vehicles or common processing equipment. The aim of this research was to quantify, by enzyme-linked immunosorbent assay (ELISA) or real-time polymerase chain reaction, the presence in meat- or fish-based foods of four allergens (milk, egg, crustaceans and molluscs) that was not indicated either in the list of ingredients or in the label alert. In the time frame of 2007-2009, a total of 723 samples were subjected to 1983 analyses. The percentage of samples scoring positive ranged between 1.8% and 6.8% over the 3 years, and the concentrations of undeclared allergens found were 0.3-13.3 mg kg⁻¹ for milk (ß-lactoglobulin) and 0.21-12 mg kg⁻¹ for egg white proteins. On this basis, the possibility of cross-contamination serious enough to raise public health concern cannot be dismissed.