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Fiore Sardo is a Protected Designation of Origin (PDO) cheese produced in Sardinia (Italy) from raw sheep’s milk, presenting risk factors due to an accumulation of Biogenic Amines (BA). A total of 37 Fiore Sardo cheese samples produced in 19 dairy farms were collected from local retail stores to evaluate BA content and its relationship with free amino acids (FAA) and composition. The following were determined for each sample: pH, water activity, composition (moisture, dry matter, NaCl, protein and fat content). FAA and BA, after extraction, were determined by HPLC-FL. The total BA content in Fiore Sardo PDO cheese samples was 127±87 mg 100 g-1, ranging between 6 and 366 mg 100 g-1. Tyramine showed the highest concentration (82±51 mg 100 g-1), followed by putrescine (21±26 mg 100 g-1). Moreover, cadaverine, histamine, β-phenylethylamine and tryptamine were detected at concentrations lower than 10 mg 100 g-1. Overall 54% of the samples analysed exceeded the threshold of 90 mg 100 g-1 for total BA content, posing a potential risk for consumers. BA, total FAA (2233±764 mg 100 g-1) and pH were positively correlated (P≤0.01) between themselves, whereas BA content was not correlated with aw, humidity and percentage of NaCl. The hierarchical cluster analysis results, considering 37 samples and 6 variables, detected four different groups. Samples with BA ≥200 mg 100 g-1 were distributed in two groups characterized by a higher proteolysis indicator levels (FAA, pH) but significantly different for aw, humidity and NaCl concentration. The results showed that high levels of BA were detectable in some samples of Fiore Sardo PDO cheese, suggesting that effective technological conditions at production should be adopted.

The aims of the present study were to evaluate the presence of Salmonella in five fermented sausage processing plants and their products during the production process, and to trace the possible sources of contamination. A total of 270 samples were collected: mixture of ground pork meat and fat, products at the end of acidification, sausages at the end of ripening and, during production stages, surfaces in contact with meat and surfaces not in contact with meat. For samples of ground meat, product at the end of acidification and sausages at the end of ripening, the pH and water activity (aw), were determined. All the samples were tested for the presence of Salmonella. Thirtytwo Salmonella isolates were obtained, subjected to serotyping and PFGE. The sausages at the end of ripening pH and aw mean values were 5.39±0.24 and 0.91±0.03, respectively. Salmonella was detected in three processing plants with an overall prevalence of 16.7% in food samples and 5.8% in environmental samples. Salmonella prevalence was 24% in ground meat and products at the end of acidification and was also detected in a sample of sausage at the end of ripening (2%). In environmental samples, Salmonella was detected in 6.6% of surfaces in contact with meat and 5% of surfaces not in contact with meat. Five serotypes were identified among 32 isolates: S. Derby (37.5%), S. Typhimurium and S. Rissen (both 25%), S. Give and monophasic S. Typhimurium (both 6.25%). Six different pulsotypes were obtained with PFGE. The serotypes and the PFGE pattern of the strains were specific for each facility with no overlapping between different processing plants. The same observation can be pointed out considering different sampling days for the same processing plants, thus presumably indicating the raw material (ground pork meat and fat) as the source of contamination. The detection of Salmonella in a sample of sausage at the end of ripening highlights the ability of the pathogen to survive during manufacturing process.

Ricotta salata cheese is a salted variety of ricotta traditionally made in Sardinia (Italy) from the whey remaining after the production of Pecorino Romano protected designation of origin or other sheep milk cheeses. Ricotta salata cheese is very critical for the possible growth of pathogenic and spoilage microorganisms. Sporadic cases of listeriosis associated with ricotta salata cheese have been reported over recent years. The objective of the present study was to assess the evolution of spoilage and pathogen microorganism of vacuum-packed ricotta salata cheese during the entire product shelf-life. The durability study was conducted on 18 vacuum-packed ricotta salata cheese samples analysed at the beginning of the shelf-life and after 60 and 90 days of refrigerated storage. Pathogens as Listeria monocytogenes and Bacillus cereus were never detected. During shelf-life total bacterial counts ranged between 7.90±0.64 and 9.19±0.58 CFU g-1 on the rind and between 2.95±0.68 and 4.27±1.10 CFU g-1 in the inner paste, while Enterobacteriaceae ranged between 4.22±0.66 and 5.30±0.73 CFU g-1 on the rind and 3.13±1.80 and 2.80±0.88 CFU g-1 in the inner paste. By considering the technology used, the intrinsic properties and the almost total absence of competing microflora, ricotta salata cheese can support the growth of spoilage and pathogen microorganisms originating from the processing environment. The high level of total bacterial counts and Enterobacteriaceae observed both on the rind and in the inner paste suggests contamination of the product from the processing environment. Therefore, a strict implementation of hygiene during processing is essential in order to reduce the load of environmental contaminants that may grow during refrigerated storage.

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