Meat spoilage
Encyclopedia
The spoilage of meat occurs, if the meat
is untreated, in a matter of hours or days and results in the meat becoming unappetizing, poisonous or infectious. Spoilage is caused by the practically unavoidable infection and subsequent decomposition
of meat by bacteria
and fungi, which are borne by the animal itself, by the people handling the meat, and by their implements. Meat can be kept edible for a much longer time – though not indefinitely – if proper hygiene
is observed during production and processing, and if appropriate food safety
, food preservation
and food storage
procedures are applied.
("exogenous
disease"). There are numerous diseases that humans may contract from endogenously infected meat, such as anthrax
, bovine tuberculosis, brucellosis
, salmonellosis
, listeriosis, trichinosis
or taeniasis
.
Infected meat, however, should be eliminated through systematic meat inspection in production, and consequently, consumers will more often encounter meat exogenously spoiled by bacteria
or fungi after the death of the animal. One source of infectious organisms is bacteraemia, the presence of bacteria in the blood of slaughtered animals. The large intestine
of animals contains some 3.3×1013 viable bacteria, which may infect the flesh after death if the carcass
is improperly dressed. Contamination can also occur at the slaughterhouse through the use of improperly cleaned slaughter or dressing implements, such as powered knives, on which bacteria persist. A captive bolt pistol
's bolt alone may carry about 400,000 bacteria per square centimeter. After slaughter, care must be taken not to infect the meat through contact with any of the various sources of infection in the abattoir, notably the hides
and soil adhering to them, water used for washing and cleaning, the dressing implements and the slaughterhouse personnel.
Bacterial genera
commonly infecting meat while it is being processed, cut, packaged, transported, sold and handled include Salmonella
spp., Shigella
spp.,
E. coli, B. proteus, S. epidermidis and Staph. aureus, Cl. welchii, B. cereus and faecal streptococci. These bacteria are all commonly carried by humans; infectious bacteria from the soil include Cl. botulinum. Among the molds commonly infecting meat are Penicillium
, Mucor
, Cladosporium
, Alternaria
, Sporotrichium and Thamnidium.
As these microorganisms colonize a piece of meat, they begin to break it down, leaving behind toxin
s that can cause enteritis
or food poisoning, potentially lethal in the rare case of botulism
. The microorganisms do not survive a thorough cooking
of the meat, but several of their toxins and microbial spore
s do. The microbes may also infect the person eating the meat, although against this the microflora of the human gut
is normally an effective barrier.
. The industry-standard Hazard Analysis Critical Control Points (HACCP) system provides for a comprehensive quality management framework as a part of which such tests can be conducted. Testing methods applied include phage
and serological typing, direct epifluorescence filter techniques (DEFT) and plasmid profiling.
Meat
Meat is animal flesh that is used as food. Most often, this means the skeletal muscle and associated fat and other tissues, but it may also describe other edible tissues such as organs and offal...
is untreated, in a matter of hours or days and results in the meat becoming unappetizing, poisonous or infectious. Spoilage is caused by the practically unavoidable infection and subsequent decomposition
Decomposition
Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...
of meat by bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
and fungi, which are borne by the animal itself, by the people handling the meat, and by their implements. Meat can be kept edible for a much longer time – though not indefinitely – if proper hygiene
Hygiene
Hygiene refers to the set of practices perceived by a community to be associated with the preservation of health and healthy living. While in modern medical sciences there is a set of standards of hygiene recommended for different situations, what is considered hygienic or not can vary between...
is observed during production and processing, and if appropriate food safety
Food safety
Food safety is a scientific discipline describing handling, preparation, and storage of food in ways that prevent foodborne illness. This includes a number of routines that should be followed to avoid potentially severe health hazards....
, food preservation
Food preservation
Food preservation is the process of treating and handling food to stop or slow down spoilage and thus allow for longer storage....
and food storage
Food storage
Food storage is both a traditional domestic skill and is important industrially. Food is stored by almost every human society and by many animals...
procedures are applied.
Infection
The organisms spoiling meat may infect the animal either while still alive ("endogenous disease") or may contaminate the meat after its slaughterAnimal slaughter
Slaughter is the term used to describe the killing and butchering of animals, usually for food. Commonly it refers to killing and butchering of domestic livestock ....
("exogenous
disease"). There are numerous diseases that humans may contract from endogenously infected meat, such as anthrax
Anthrax
Anthrax is an acute disease caused by the bacterium Bacillus anthracis. Most forms of the disease are lethal, and it affects both humans and other animals...
, bovine tuberculosis, brucellosis
Brucellosis
Brucellosis, also called Bang's disease, Crimean fever, Gibraltar fever, Malta fever, Maltese fever, Mediterranean fever, rock fever, or undulant fever, is a highly contagious zoonosis caused by ingestion of unsterilized milk or meat from infected animals or close contact with their secretions...
, salmonellosis
Salmonellosis
Salmonellosis is an infection with Salmonella bacteria. Most people infected with Salmonella develop diarrhea, fever, vomiting, and abdominal cramps 12 to 72 hours after infection. In most cases, the illness lasts four to seven days, and most people recover without treatment...
, listeriosis, trichinosis
Trichinosis
Trichinosis, also called trichinellosis, or trichiniasis, is a parasitic disease caused by eating raw or undercooked pork or wild game infected with the larvae of a species of roundworm Trichinella spiralis, commonly called the trichina worm. There are eight Trichinella species; five are...
or taeniasis
Taeniasis
Taeniasis is a form of tapeworm infection which is caused by tapeworms of the genius Taenia.The two most important human pathogens in the genus are Taenia solium and Taenia saginata . Infection is acquired by eating undercooked contaminated meat. The adult worms live in the lumen of the intestine...
.
Infected meat, however, should be eliminated through systematic meat inspection in production, and consequently, consumers will more often encounter meat exogenously spoiled by bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
or fungi after the death of the animal. One source of infectious organisms is bacteraemia, the presence of bacteria in the blood of slaughtered animals. The large intestine
Large intestine
The large intestine is the third-to-last part of the digestive system — — in vertebrate animals. Its function is to absorb water from the remaining indigestible food matter, and then to pass useless waste material from the body...
of animals contains some 3.3×1013 viable bacteria, which may infect the flesh after death if the carcass
Body
With regard to living things, a body is the physical body of an individual. "Body" often is used in connection with appearance, health issues and death...
is improperly dressed. Contamination can also occur at the slaughterhouse through the use of improperly cleaned slaughter or dressing implements, such as powered knives, on which bacteria persist. A captive bolt pistol
Captive bolt pistol
A captive bolt pistol is a device used for stunning animals prior to slaughter....
's bolt alone may carry about 400,000 bacteria per square centimeter. After slaughter, care must be taken not to infect the meat through contact with any of the various sources of infection in the abattoir, notably the hides
Hides
A hide is an animal skin treated for human use. Hides include leather from cattle and other livestock animals, alligator skins, snake skins for shoes and fashion accessories and furs from wild cats, mink and bears. In some areas, leather is produced on a domestic or small industrial scale, but most...
and soil adhering to them, water used for washing and cleaning, the dressing implements and the slaughterhouse personnel.
Bacterial genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
commonly infecting meat while it is being processed, cut, packaged, transported, sold and handled include Salmonella
Salmonella
Salmonella is a genus of rod-shaped, Gram-negative, non-spore-forming, predominantly motile enterobacteria with diameters around 0.7 to 1.5 µm, lengths from 2 to 5 µm, and flagella which grade in all directions . They are chemoorganotrophs, obtaining their energy from oxidation and reduction...
spp., Shigella
Shigella
Shigella is a genus of Gram-negative, nonspore forming, non-motile, rod-shaped bacteria closely related to Escherichia coli and Salmonella. The causative agent of human shigellosis, Shigella causes disease in primates, but not in other mammals. It is only naturally found in humans and apes. During...
spp.,
E. coli, B. proteus, S. epidermidis and Staph. aureus, Cl. welchii, B. cereus and faecal streptococci. These bacteria are all commonly carried by humans; infectious bacteria from the soil include Cl. botulinum. Among the molds commonly infecting meat are Penicillium
Penicillium
Penicillium is a genus of ascomycetous fungi of major importance in the natural environment as well as food and drug production. Members of the genus produce penicillin, a molecule that is used as an antibiotic, which kills or stops the growth of certain kinds of bacteria inside the body...
, Mucor
Mucor
Mucor is a microbial genus of about 3000 species of moulds commonly found in soil, digestive systems, plant surfaces, and rotten vegetable matter.-Description:...
, Cladosporium
Cladosporium
Cladosporium is a genus of fungi including some of the most common indoor and outdoor molds. Species produce olive-green to brown or black colonies, and have dark-pigmented conidia that are formed in simple or branching chains....
, Alternaria
Alternaria
Alternaria is a genus of ascomycete fungi. Alternaria species are known as major plant pathogens. They are also common allergens in humans, growing indoors and causing hay fever or hypersensitivity reactions that sometimes lead to asthma...
, Sporotrichium and Thamnidium.
As these microorganisms colonize a piece of meat, they begin to break it down, leaving behind toxin
Toxin
A toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...
s that can cause enteritis
Enteritis
In medicine, enteritis, from Greek words enteron and suffix -itis , refers to inflammation of the small intestine. It is most commonly caused by the ingestion of substances contaminated with pathogenic microorganisms. Symptoms include abdominal pain, cramping, diarrhea, dehydration and fever...
or food poisoning, potentially lethal in the rare case of botulism
Botulism
Botulism also known as botulinus intoxication is a rare but serious paralytic illness caused by botulinum toxin which is metabolic waste produced under anaerobic conditions by the bacterium Clostridium botulinum, and affecting a wide range of mammals, birds and fish...
. The microorganisms do not survive a thorough cooking
Cooking
Cooking is the process of preparing food by use of heat. Cooking techniques and ingredients vary widely across the world, reflecting unique environmental, economic, and cultural traditions. Cooks themselves also vary widely in skill and training...
of the meat, but several of their toxins and microbial spore
Spore
In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...
s do. The microbes may also infect the person eating the meat, although against this the microflora of the human gut
Gut (zoology)
In zoology, the gut, also known as the alimentary canal or alimentary tract, is a tube by which bilaterian animals transfer food to the digestion organs. In large bilaterians the gut generally also has an exit, the anus, by which the animal disposes of solid wastes...
is normally an effective barrier.
Testing
The presence of infectious agents can be detected with a number of tests during the production and processing of meat, but testing by itself is not sufficient to ensure adequate food safetyFood safety
Food safety is a scientific discipline describing handling, preparation, and storage of food in ways that prevent foodborne illness. This includes a number of routines that should be followed to avoid potentially severe health hazards....
. The industry-standard Hazard Analysis Critical Control Points (HACCP) system provides for a comprehensive quality management framework as a part of which such tests can be conducted. Testing methods applied include phage
Phage typing
Phage typing is a method used for detecting single strains of bacteria. It is used to trace the source of outbreaks of infections. The viruses that infect bacteria are called bacteriophages and some of these can only infect a single strain of bacteria...
and serological typing, direct epifluorescence filter techniques (DEFT) and plasmid profiling.
Microbial spoilage
Depending on oxygen availability, meat spoilage by micro-organisms can manifest itself as follows:| Oxygen | Microbial agent | Symptoms |
|---|---|---|
| Present | Aerobic bacteria |
|
| Present | Yeast Yeast Yeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding... s |
|
| Present | Mold Mold Molds are fungi that grow in the form of multicellular filaments called hyphae. Molds are not considered to be microbes but microscopic fungi that grow as single cells called yeasts... s |
|
| Absent | Anaerobic bacteria |
Putrefaction Putrefaction is one of seven stages in the decomposition of the body of a dead animal. It can be viewed, in broad terms, as the decomposition of proteins, in a process that results in the eventual breakdown of cohesion between tissues and the liquefaction of most organs.-Description:In terms of... and foul odors |