Food Protection Trends - February 2010 - 100

Conclusions: the real time PCR assay combined with the adiapure Map-Dna extraction kit represents a reproducible, sensitive and convenient method for detection of Map Dna from a range of raw and pasteurized dairy products. Its robustness has been confirmed through a ring trial within the FP6 eU ParatBtools project. Acknowledgments: this work was funded as part of the eU FP6 ParatBtools project – FooD – Ct-2006– 023106. P1-31 A Method for the Laboratory-scale Manufacture of UK Semi-Hard and Hard Type Cheeses from Milk Contaminated with Mycobacterium bovis RICHARD FORGRAVE, John Donaghy, and Michael Rowe, Queen’s University Belfast, school of Biological sciences, newforge Lane, Belfast, Ireland Introduction: although the UK has established control and monitoring mechanisms for tuberculosis in cattle the prevalence of tuberculosis amongst dairy herds continues to increase. Concomitantly there is a growing market for artisanal cheeses produced from raw milk. the absence of a pasteurisation process removes a major barrier to possible Mycobacterium bovis contamination of raw milk cheeses. a link between M. bovis zoonotic infections and the consumption of raw milk and related products has been established. Rational: Currently a lack of data exists regarding the survival kinetics of M. bovis during the manufacture, ripening and storage of raw milk cheeses. to address this knowledge gap it was essential to devise a protocol for the production of semi-hard (Caerphilly) and hard cheese (Cheddar). the cheesemaking procedure must satisfy stringent health and safety criteria regarding manipulation of Hazard Group 3 organisms and produce on a laboratory-scale cheese comparable with commercial products. Results: the devised procedure mimics the cutting and stacking of curd, traditionally used to develop the characteristic texture of cheddar cheese. equipment developed facilitates the application of constant, measurable and reproducible pressure during pressing. all cheesemaking manipulations can be conducted within the confines of a Class I safety cabinet. Containment measures allow for the safe collection of whey and subsequent disposal. Cheddar and Caerphilly cheeses prepared from raw milk artificially contaminated with M. bovis have been produced and M. bovis has been enumerated on selective media post manufacture. Conclusions: this procedure allows the investigation of M. bovis survival kinetics in raw milk cheeses. Furthermore the technique could be used with other Hazard Group 2 & 3 pathogens and adaptation is possible for production of alternative cheese types. as a result this protocol is a tool for the production of microbiologically contaminated cheese which can facilitate investigation of food protection relating to cheese. Acknowledgments: the authors acknowledge funding received for this project from the Food standards agency (UK). P1-32 Qualitative Methods for the Detection of Listeria monocytogenes and Other Listeria Species – Strategies for Comparison Studies MaRIJa zUnaBoVIC, Wolfgang Kneifel, University of natural Resources and applied Life science, Vienna, 1190, austria Introduction: Current approved methods allow the detection of the food pathogen L. monocytogenes from various food matrices. For the detection three general procedures can be described: (1) direct plating on selective media (2) immediate selective enrichment (3) pre-enrichment steps. of course the choice of the “ideal” method for specific purpose is dependent on different parameters (e.g., number and stage of microorganisms, inhibitory aspects of the media, incubation time and conditions). on the other hand the treatment of samples for efficient detecting of especially low levels and inhomogeneous spreading of microorganisms is also essential. Rational: the preparation and design for the comparison of qualitative methods based on different methodologies for detection of the emerging food pathogen Listeria monocytogenes and other Listeria species is described. the matrices were naturally contaminated and sampled in different food factories (seafood, cabbage, ready-to-eat food) and therefore reflect the real situation. Results: this protocol was successfully applied for comparison studies with VIDas® LDUo (bioMérieux), IQCheck® Listeria (Biorad), and BaX® Listeria PCR (DuPont) run in parallel with the reference method according to Iso 11290:1. It allows the evaluation of these methods by the use of current parameters as specifity, sensitivity, false-positive and false-negative rate for alternative methods. Conclusions: For estimating the prevalence of Listeria spp. and Listeria monocytogenes e.g., in neuralgic areas in the food production and in food products it is essential to combine methodologies for an effective detection. the problem of obtaining a representative sample of food or environment is persistent due to uneven spread of contamination. Comparison studies with alternative methods are difficult to perform because they rely on different detection principles (e.g., monoclonal antibodies, virulence genes, enzymes, and ribosome) and the sensitivity is rising with upcoming new methods. even though the analyzing time and information content about the presence of Listeria can be fulfilled with the use of alternative methods. 100 FOOD PROTECTION TRENDS | FEBRUARY 2010

Food Protection Trends - February 2010

Table of Contents for the Digital Edition of Food Protection Trends - February 2010