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Food Microbiology Microbiological shelf life |
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Shelf life is defined as the time after production during which a product remains acceptable for consumption. The product must remain safe and retain acceptable sensory, microbiological and chemical characteristics. Key aspects for consideration when determining microbiological shelf life are given below. We can provide wide-ranging advice on these and other factors of concern. Minimum growth characteristics Microorganisms differ in their abilities to tolerate environmental conditions such as temperature and pH. Information on growth characteristics will determine which organisms are likely to grow in a product. Product formulation Many ingredients added to foodstuffs are antimicrobial. These ingredients can include salt, preservatives and acid. Microorganisms can tolerate many of these stresses and if adapted to one stressful situation (e.g. chill temperature) can become more resistant to a second stress such as lowered pH. The order in which these stresses are applied could also be important. Preservative systems Preservatives are often added to a foodstuff to help prolong shelf life. Traditionally chemical preservatives such as sorbate and benzoate have been used. However, a number of natural ingredients such as clove, thyme and garlic have been shown to have an antimicrobial effect and have the potential to extend shelf life. Predictive modelling The growth of a range of microorganisms can be predicted using computer models. Parameters such as lag time, and time to reach a specific level can be predicted. Predictions can be used to assign shelf life but can also be used in product development to assess formulation changes, and in troubleshooting where a production problem such as increased storage temperature has occurred. Shelf life testing This is a lab based determination of microbiological activity within a food over time. Product is stored under the required storage conditions and tested at suitable time points for relevant organisms. CCFRA offers a shelf life evaluation service which can incorporate sensory and chemical analysis. Product can also be produced and/or packaged on site in our process hall. Challenge testing This is a practical study to determine the behaviour of relevant organisms if they should be present in a product. It involves deliberate inoculation of the product with relevant organisms. The product is then stored and tested for these organisms during shelf life. CCFRA offers expert advice and guidance on challenge testing and can undertake challenge tests with a wide range of organisms including E.coli O157 and C.botulinum. Microbial measures of product quality Deterioration in sensory quality and/or an increase in microbial numbers can limit the shelf life of a product. There is an increase in use of microbial specifications for determining shelf life but often an increase in microbial numbers does not always relate to a decrease in sensory quality. Produce decontamination Fresh produce is naturally contaminated with a range of microorganisms that can include pathogens. Decontamination by a range of techniques is used to help remove any pathogens that may be present and reduce the level of spoilage organisms. This can help maintain product safety and extend shelf life. |
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Contact:
info@campden.co.uk We are constantly developing and refining our services.
Other food microbiology services |
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