Microbiology of Meat, Poultry and Marine Foods

The microbiological profile of meat products presented to the consumers is the sum total of the slaughtered animal health, conditions under which it was reared, quality of slaughtering, processing, packaging and conditions under which the meat was stored. Meat can act as an ideal substrate for microbial proliferation. Major meat associated pathogenic bacteria include Clostridium perfringens, Staphylococcus aureus, Salmonella spp, pathogenic strains of Escherichia coli, Campylobacter spp, Yersinia enterocolitica, Listeria monocytogenes and Aeromonas hydrophila. Meat spoilages indicate (a) color changes (b) textural changes and (c) development of off-flavour or off-odor or slime as a result of microbial growth.

Freshly laid eggs are generally sterile particularly the inner contents. In general the spoilage of eggs is caused by bacteria as compared to molds and can be described as green rot due to the growth of Pseudomonas fluorescens, colourless rot due to the growth of Pseudomonas, Acinetobacter and other species; black rots due to Proteus, Pseudomonas; red rots due to Serratia spp. and custrad rots due to Proteus vulgaris and Pseudomonas intermedium. Growth of Aeromonas in the egg yolk turns it to black colour and also there is strong putrid odour due to the formation of hydrogen sulphide.

Poultry meat like meat of other animals is also susceptible to contamination by various sources. Contamination of skin and lining of the body cavity take place during various processing operations. The organisms of great importance in poultry are Salmonella spp. and Campylobacter jejuni. Several Gram negative psychrotropic bacteria viz., Pseudomonas, Acenitobacter and Flavobacterium have also been isolated from poultry carasses. Ground turkey also may carry fecal streptococci. It is important to freeze the poultry fast in order to keep it in good condition for several months. Freezing further reduces the number of microorganisms in the poultry meat provided the temperature is maintained quite low (-18 ° C or below).

Fish is a very perishable, high-protein food that typically contains a high level of free amino acids. Halophilic bacteria like Serratia, Micrococcus, Bacillus, Alcaligenes and Pseudomonas cause spoilage of salt fish. Shell fish are spoiled by Acenetobacter, Moraxella and Vibrio. Crab meat is spoiled by Pseudomonas, Acinetobacter and Moraxella at low temperature and by Proteus at high temperature.