8 Meat refrigeration Table 1.1 Minimum and optimum growth temperatures for pathogens associated with red meats Optimun (°C) C Clostridia perfringens Pathogenic escherichia coli strains Salmonella spp Listeria monocytogenes 027502 43-47 35-40 30-37 Yersinia enterocolitica Source: Mead and Hinton. 1996. 1. 1). The greatest reduction in the microbial load occurs during, or shortly after, freezing itself. During frozen storage, the numbers are gradually reduced further 1.2.1 Pathogenic organisms A number of bacterial pathogens capable of causing food poisoning in humans are known to contaminate red meat. Those of most importance are Campylobacter spp, Clostridium perfringenS, pathogenic serotypes of Escherichia coli (principally E coli o157: H7), Salmonella spp and Yersinia enterocolitica(Nottingham, 1982; Anon, 1993; Mead and Hinton, 1996).Lis- teria monocytogenes is commonly associated with meat, but its public health significance in relation to raw meat is unclear (Mead and Hinton, 1996) The essential characteristics of pathogenic micro-organisms can be found In numerous texts Minimum and optimum growth temperatures for pathogens commonly associated with red meat are show in Table 1.1. Some pathogens, such as L. monocytogens nes,are capable of growth at chill temperatures below 5C. These are often cited as being of particular concern in relation to refriger ated meats since refrigeration can not be relied on to prevent growth (Doyle, 1987). On the other hand, psychrotrophic pathogens are not par ticularly heat resistant and adequate cooking should be sufficient to destroy any such pathogens. Illnesses caused by L. monocytogenes and E coli are often due to inadequate cooking before ingestion 1.2.2 Spoilage organisms The number of types of micro-organisms capable of causing food spoilage is very large and it is not possible to discuss them in any detail in this text Depending on the initial microflora and the growth environment, only a few species of the genera Pseudomonas, Acinetobacter, Moraxella Lactobacillus, Brochothrix and Alteromonas, and of the family1.1). The greatest reduction in the microbial load occurs during, or shortly after, freezing itself. During frozen storage, the numbers are gradually reduced further. 1.1.2.1 Pathogenic organisms A number of bacterial pathogens capable of causing food poisoning in humans are known to contaminate red meat. Those of most importance are Campylobacter spp., Clostridium perfringens, pathogenic serotypes of Escherichia coli (principally E. coli O157:H7), Salmonella spp. and Yersinia enterocolitica (Nottingham, 1982; Anon, 1993; Mead and Hinton, 1996). Lis￾teria monocytogenes is commonly associated with meat, but its public health significance in relation to raw meat is unclear (Mead and Hinton, 1996). The essential characteristics of pathogenic micro-organisms can be found in numerous texts. Minimum and optimum growth temperatures for pathogens commonly associated with red meat are show in Table 1.1. Some pathogens, such as L. monocytogenes, are capable of growth at chill temperatures below 5 °C. These are often cited as being of particular concern in relation to refriger￾ated meats since refrigeration can not be relied on to prevent growth (Doyle, 1987). On the other hand, psychrotrophic pathogens are not par￾ticularly heat resistant and adequate cooking should be sufficient to destroy any such pathogens. Illnesses caused by L. monocytogenes and E. coli are often due to inadequate cooking before ingestion. 1.1.2.2 Spoilage organisms The number of types of micro-organisms capable of causing food spoilage is very large and it is not possible to discuss them in any detail in this text. Depending on the initial microflora and the growth environment, only a few species of the genera Pseudomonas, Acinetobacter, Moraxella, Lactobacillus, Brochothrix and Alteromonas, and of the family 8 Meat refrigeration Table 1.1 Minimum and optimum growth temperatures for pathogens associated with red meats Minimum temperature Optimum temperature (°C) (°C) Campylobacter spp. 30 42–43 Clostridia perfringens 12 43–47 Pathogenic Escherichia 7 35–40 coli strains Salmonella spp. 5 35–43 Listeria monocytogenes 0 30–37 Yersinia enterocolitica -2 28–29 Source: Mead and Hinton, 1996