Bacteriological Analytical Manual (original) (raw)
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Modern and Rapid Methods for Toxicological Analysis of Foodstuffs with Bacterial Contamination
Applied Researches in Technics, Technologies and Education, 2018
Foodborne illnesses are a widespread problem throughout the world. Food poisoning due to bacterial toxins can be caused by the ingestion of exotoxins which are preformed in the food, or by the ingestion of food containing large numbers of bacterial cells which then release endotoxins in the gastrointestinal tract. Early methods for the assay of bacteria toxins were based on in vivo or in vitro tests. Later, immunological tests were developed based on techniques such as gel diffusion. Different types of methods have been developed for the detection of toxin genes and their toxic products. These methods include the detection of toxin genes by amplification methods and hybridization probing. There are now a number of rapid test kits available which give results within hours and are much simpler to perform and interpret than bioassays.
Methods Committee on Microbiology
Journal of AOAC International, 2010
The General Referee concurs. Continue study. (4) OMA-2009-Jul-008, Detection of Salmonella species in Selected Foods by the Assurance GDS รข for Salmonella.-Study Director Philip T. Feldsine. A collaborative study protocol has been approved by the Methods Committee. The study has been completed and the manuscript is in review. Continue study. (5) 996.14, Assurance Polyclonal Enzyme Immunoassay (EIA) for the Detection of Listeria monocytogenes in Selected Foods and from Environmental Surfaces.
The validation of alternative microbiological testing is an opportunity for a manufacturer to decrease the amount of time required for laboratory results.To properly validate these alternatives, a practitioner must first identify what is being studied. The regulatory effect on established product and process specifications and levels must be completely evaluated, as changing the method of analysis may well change the apparent number in the sample.
Rapid test methods: a versatile tool to assist food-safety
2010
Introduction Rapid test methods are increasingly being promoted as tools for food companies to validate and/or verify the efficacy of their food-safety management systems. However, little is known about their take-up by the industry nor on what industry's current and future needs are. Objectives In order to gain further information a questionnaire-based survey was conducted in 17 countries (11 European Union members and 6 non-European Union members). The survey was designed to gain insight into routine analytical regimes operated by food industries and the role played in them by the use of rapid test methods. Methods Over 2600 questionnaires were circulated to companies covering the whole food chain and 661 replies (about 25%) were received. Results At a strategic level, the survey revealed that raw materials and final products are the most routinely analyzed samples, and that the major analytes tested for concerned (in descending order) microbiological contaminants, heavy metals, pesticides, foreign bodies, mycotoxins and allergens. With regard to the use of rapid test methods, 66% of the respondents use them, while, almost all respondents stated their interest for extending the range of tests performed. In terms of future needs, rapid tests for microbiological analysis was emphasized by most respondents, while food allergens and mycotoxins-related test kits were also of high importance. Conclusions The results obtained indicate that the food industries currently use or are well prepared for the implementation of new rapid methods of analysis.
A rapid and reliable alternative to ISO 21528-1:2004 for detection of Enterobacteriaceae
International Journal of Food Microbiology, 2008
Alternative method Current legislation in Europe uses the Enterobacteriaceae as a parameter in process hygiene criteria for various food products and refers to the corresponding ISO standard (ISO 21528-1:2004) as mandatory analytical method for this purpose. The ISO procedure includes an enrichment step in EE ("Enterobacteriaceae Enrichment") broth, but it has been reported recently that some isolates of Enterobacteriaceae do not grow well or will even die off in this broth, which could lead to false negative results. To determine if this trait is common among the Enterobacteriaceae, a collection of 95 strains was screened for growth in EE broth. Inhibition was observed with 9 strains (7 Cronobacter sakazakii, 1 Cronobacter malonaticus and 1 Enterobacter amnigenus). Factors affecting cell death were found to be related mainly to the inclusion of bile salts and dyes in this medium. In a second step, an alternative method omitting the EE broth was evaluated using 326 samples, comprising 8 different food matrices and environmental samples from the corresponding manufacturing sites. Positive results were obtained for 235 samples using the ISO standard method and 232 samples using the alternative shortened method. No significant difference was found between the results for the two methods. It is proposed that the standard method for detection of Enterobacteriaceae is revised accordingly.
Food Analytical Methods, 2014
Microbiological analysis is an integral part of food quality control, as well as of the management of food chain safety. Microbiological testing of foodstuffs complements the preventive approach to food safety activities based mainly on implementation and application of the concept of Hazard Analysis and Critical Control Points (HACCP). Traditional microbiological methods are powerful but lengthy and cumbersome and therefore not fully compatible with current requirements. Even more, pathogens exist that are fastidious to cultivate or uncultivable at all. Besides immunological tests, molecular methods, specifically those based on polymerase chain reaction (PCR), are available options to meet industry and enforcement needs. The clear advantage of PCR over all other rapid methods is the striking analytical principle that is based on amplification of DNA, a molecule being present in every cell prone to multiply. Just by changing primers and probes, different genomes such as bacteria, viruses or parasites can be detected. A second advantage is the ability to both detect and quantify a biotic contaminant. Some previously identified obstacles of implementation of molecular methods have already been overcome. Technical measures became available that improved robustness of molecular methods, and equipment and biochemicals became much more affordable. Unfortunately, molecular methods suffer from certain drawbacks that hamper their full integration to food safety control. Those encompass a suitable sample pre-treatment especially for a quantitative extraction of bacteria and viruses from solid foods, limited availability of appropriate controls to evaluate the effectiveness of the analytical procedure, the current inability of molecular methods to distinguish DNA from viable cells and DNA from dead or non-cultivable cells, and the slow progress of international harmonisation and