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Evaluation of Listeria monocytogenes contamination in sheep’s milk cheese-making plants

Ibba, Michela (2015) Evaluation of Listeria monocytogenes contamination in sheep’s milk cheese-making plants. Doctoral Thesis.

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Abstract

The general aim of the thesis was to evaluate the pattern Listeria monocytogenes contamination in sheep’s milk industrial cheese-making plants operating in the regional territory of Sardinian (Italy). Chapter 3 describes a longitudinal study conducted in 2 cheese-making plants over one year period. The objective of the study was to identify sources, sites of persistence and route of contamination within premises. Contamination mostly occurred in salting, product washing, packaging, ricotta salata storage and cheese ripening areas. The greater persistence of contamination over time was observed in washing, salting and cheese ripening areas. In Chapter 4 is presented a cross-sectional study on Listeria spp environmental contamination in 13 sheep cheese-making plants. The objective was to investigate the genetic diversity (population study) and the route of contamination (traceability) of L. monocytogenes strains. Strains originating from the processing environment were disseminated to other sites and food samples within and among facilities. In chapter 5 the potential pathogenicity of environmental and food isolates collected in cheese-making plants was studied by DNA sequencing. In particular the modification in nucleotide sequence of virulence factors hly, InlA and InlJ was investigated. L. monocytogenes environmental strains showed 90-100% of identity with reference sequences, suggesting their potential pathogenicity.

Item Type:Doctoral Thesis
ID Code:10374
Contributors:Spanu, Carlo
Publisher:Università degli studi di Sassari
Uncontrolled Keywords:Food safety, Listeria monocytogenes, cheese-making plants, environmetal contamination
Subjects:Area 07 - Scienze agrarie e veterinarie > VET/04 Ispezione degli alimenti di origine animale
Divisions:001 Università di Sassari > 01-a Nuovi Dipartimenti dal 2012 > Medicina Veterinaria
Cicli, scuole e corsi:Ciclo 27 > Scienze Veterinarie > Produzione, qualità e sicurezza degli alimenti di origine animale
Deposited On:18 Mar 2015 09:55

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