ReviewThe safety of pasteurised in-pack chilled meat products with respect to the foodborne botulism hazard
Section snippets
Introduction to pasteurised in-pack chilled products
Consumer demand for foods that require minimal preparation time compared with conventional meals, are of high quality, contain low levels of preservatives, and are only minimally processed has led to the development of foods that are pasteurised in-pack. These foods are also known as sous-vide foods, cook-chill ready-to-eat foods, and refrigerated processed foods of extended durability (REPFEDs). These foods are processed at a lower temperature (maximum generally within the range 70–95 °C) than,
Assessment of microbiological safety hazards associated with pasteurised in-pack chilled products
Pasteurised in-pack products are not sterile, and safety and quality is dependent on a combination of the minimal heat process, storage temperature, shelf-life and perhaps also intrinsic properties of the food (Peck, 1997). The mild heat treatment applied should eliminate cells of vegetative bacteria, but not bacterial or fungal spores. Thus, non-spore-forming pathogens such as Listeria monocytogenes, Yersinia enterocolitica, diarrheagenic Escherichia coli, Campylobacter jejuni, and salmonellae
Recommendations and guidelines to ensure the safe production of pasteurised in-pack chilled products with respect to Clostridium botulinum
Guidelines and a code of practice have been targeted at ensuring the safe production of these foods by preventing growth and toxin production by non-proteolytic C. botulinum (ACMSF, 1992, ACMSF, 1995, Betts, 1996, ECFF, 1996, Gould, 1996, Gould, 1999, Martens, 1997). Growth and toxin production by proteolytic C. botulinum is prevented by ensuring storage is below 10 °C. Recommendations produced by the UK Advisory Committee on the Microbiological Safety of Food (ACMSF) on procedures to ensure
Characteristics of Clostridium botulinum and other neurotoxin producing clostridia
Six physiologically and phylogenetically distinct Gram-positive spore-forming anaerobic bacteria can produce botulinum neurotoxin (Table 2), although the name of C. botulinum is retained to emphasise the importance of neurotoxin production (Lund & Peck, 2000). Some strains of C. baratii and C. butyricum also produce neurotoxin. For each of the six organisms, a non-neurotoxigenic phylogenetically equivalent organism is known (Hatheway, 1992). The different physiology of the six organisms is
Factors influencing growth and toxin formation
Providing that pasteurised in-pack chilled products are stored at an appropriate temperature, growth and toxin production by proteolytic C. botulinum is prevented. There is, however, concern that proteolytic C. botulinum may grow and form toxin in products that are temperature abused. The effect of individual environmental factors on growth of proteolytic C. botulinum, under otherwise optimum conditions, has been established. The minimum temperature at which growth and toxin production occurs
Control of infant botulism hazard presented by proteolytic Clostridium botulinum in pasteurised in-pack chilled meat products
Infant botulism is an infection. An immature intestinal flora in infants is unable to prevent colonisation by proteolytic C. botulinum (and also neurotoxigenic strains of C. baratii and C. butyricum ), allowing ingested spores to germinate leading to cell multiplication and neurotoxin production. Infants aged between 2 weeks and 6 months are most susceptible. Symptoms typically include extended constipation and flaccid paralysis. Infant botulism is rarely fatal. Two sources of spores have been
Factors influencing growth and toxin formation
The minimum temperature at which growth and toxin production have been described is 3.0 °C (Graham, Mason, Maxwell, & Peck, 1997). In this study, vials containing 10 ml of PYGS (peptone, yeast extract, glucose, starch) medium were inoculated at 104 spores/ml, and growth was observed at 3.0 °C after 7 weeks, 3.1 °C after 6 weeks, and 3.2 °C after 5 weeks. The presence of toxin was confirmed. Earlier studies had demonstrated growth and toxin production at 3.3 °C within 5 weeks (Eklund et al., 1967a, Eklund
Acknowledgement
The authors are grateful to the competitive strategic grant of the BBSRC for funding.
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