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The Food Standards Agency has identified that some microbiological methods routinely used may not be adequate for recovering microorganisms from some types of meat preparations. Two particular areas of concern were that sample homogenisation methods may not be effective in recovering microbes from fatty meats and that marinade sauces present on some meat preparations might inhibit growth of pathogens during the pre-enrichment phase of isolation. <P>
This project aimed to investigate methods for improving the recovery of bacteria from fatty meats and from meat preparations and marinades containing spices.
Research Approach: The first part of the project examined whether the inclusion of surfactant Tween-80 in the diluent used to prepare homogenates would improve recovery of microbes from fatty beef mince. Two different homogenisation methods were tested: the stomacher and the pulsifier.
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The second part of the project examined whether marinade sauces would inhibit multiplication of Salmonella Typhimurium during the pre-enrichment step in buffered peptone water (BPW) that forms the first stage in standard isolation protocols. Thirty-two different marinade sauces were tested.
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Results and Findings: The addition of the recommended concentration of Tween-80 (1%) to diluents or media used for sample preparation with the stomacher or pulsifier will have no significant effect on the recovery of microbes from fatty meat preparations.
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When examining meat preparations containing acidic marinades with spices, double-strength BPW should be used as the pre-enrichment medium. This will nullify the inhibitory effect of acidic marinades containing spices allowing low numbers of salmonellae to be detected.
<p>Find more about this project and other FSA food safety-related projects at the <a href="http://www.food.gov.uk/science/research/" target="_blank">Food Standards Agency Research webpage</a>.