Microbial flora of meat and meat products
All forms of foods in their natural state remain in a fresh and edible state for only a comparatively short time. It means the shelf life of meat like other food items are relatively short at environmental temperature. Besides the presence of other nutrients in the meat, it is a protein rich animal food source for which microbes also get attached to its surface and becomes colonize.
Bacteria are everywhere, the most common ways in which bacteria and other micro-organisms spread are in the air, by contact and via insects and other creatures. In meat processing, the common way of spread of micro-organisms to meat is through cross contamination from dirty equipment, personal gear, hands and hides and skins, fleece and feathers or the digestive tract.
Food microbiology is important in meat hygiene for the purposes of protection of the consumer against food-borne microbial diseases and the prevention of meat spoilage due to microbial activities. Food micro-flora are basically bacteria and moulds.
Moulds: These are multicellular, filamentous fungi that grow on foods. They have cottony appearance and may sometimes be colored. While some are useful (e.g. in the production of cheese), others cause spoilage of food thus making such food unfit for human consumption. Some in addition to spoilage produce various toxic metabolites such as mycotoxin that is toxic.
Bacteria: Bacterial growth in and on meat is often extensive, this can cause spoilage and makes meat unattractive in appearance. Pigmented bacteria cause discoloration on the surfaces of raw meat. Bacterial growth in liquid such as milk may result in cloudiness or sedimentation.
Fresh meats may be initially contaminated from many different sources such as soil, dust, faeces, water and equipment as well as from the hands and clothing of personnel. Processed meat foods are also prone to contamination with pathogenic microorganisms during various stages of processing.
Meat borne diseases are associated with consumption of meat. The following are the bacteria commonly associated with meat spoilage and are important in meat hygiene: Pseudomonas, Vibrio, Escherichia, Salmonella, Enterobacter, Shigella, Klebsiella, Yersinia, Streptococcus, Staphylococcus, Listeria and Lactobacilli. Ready to eat meat are also a part of concern. They can be good growth substrates for various microorganisms.