Meat spoilage
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The spoilage of meat occurs, if the
meat Meat is animal flesh that is eaten as food. Humans have hunted, farmed, and scavenged animals for meat since prehistoric times. The establishment of settlements in the Neolithic Revolution allowed the domestication of animals such as chic ...
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 or rot is the process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts. The process is a part of the nutrient cycle and is e ...
of meat by
bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
and
fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
, 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 is a series of practices performed to preserve health. According to the World Health Organization (WHO), "Hygiene refers to conditions and practices that help to maintain health and prevent the spread of diseases." Personal hygiene refer ...
is observed during production and processing, and if appropriate
food safety Food safety (or food hygiene) is used as a scientific method/discipline describing handling, preparation, and storage of food in ways that prevent food-borne illness. The occurrence of two or more cases of a similar illness resulting from t ...
,
food preservation Food preservation includes processes that make food more resistant to microorganism growth and slow the oxidation of fats. This slows down the decomposition and rancidification process. Food preservation may also include processes that inhibit ...
and
food storage Food storage is a way of decreasing the variability of the food supply in the face of natural, inevitable variability. p.507 It allows food to be eaten for some time (typically weeks to months) after harvest rather than solely immediately. I ...
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 slaughter ("exogenous disease").Lawrie, 157. There are numerous diseases that humans may contract from endogenously infected meat, such as
anthrax Anthrax is an infection caused by the bacterium ''Bacillus anthracis''. It can occur in four forms: skin, lungs, intestinal, and injection. Symptom onset occurs between one day and more than two months after the infection is contracted. The sk ...
,
bovine tuberculosis Bovines ( subfamily Bovinae) comprise a diverse group of 10 genera of medium to large-sized ungulates, including cattle, bison, African buffalo, water buffalos, and the four-horned and spiral-horned antelopes. The evolutionary relationship betw ...
,
brucellosis Brucellosis is a highly contagious zoonosis caused by ingestion of unpasteurized milk or undercooked meat from infected animals, or close contact with their secretions. It is also known as undulant fever, Malta fever, and Mediterranean fever. The ...
,
salmonellosis Salmonellosis, more commonly known as food poisoning is a symptomatic infection caused by bacteria of the ''Salmonella'' type. It is also a food-borne disease and are defined as diseases, usually either infectious or toxic in nature, caused by a ...
,
listeriosis Listeriosis is a bacterial infection most commonly caused by ''Listeria monocytogenes'', although '' L. ivanovii'' and '' L. grayi'' have been reported in certain cases. Listeriosis can cause severe illness, including severe sepsis, men ...
,
trichinosis Trichinosis, also known as trichinellosis, is a parasitic disease caused by roundworms of the ''Trichinella'' type. During the initial infection, invasion of the intestines can result in diarrhea, abdominal pain, and vomiting. Migration of larv ...
or
taeniasis Taeniasis is an infection within the intestines by adult tapeworms belonging to the genus '' Taenia''. There are generally no or only mild symptoms. Symptoms may occasionally include weight loss or abdominal pain. Segments of tapeworm may be see ...
.Lawrie, 158. Infected meat, however, should be eliminated through systematic meat inspection in
production Production may refer to: Economics and business * Production (economics) * Production, the act of manufacturing goods * Production, in the outline of industrial organization, the act of making products (goods and services) * Production as a stati ...
, and consequently, consumers will more often encounter meat exogenously spoiled by
bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
or
fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
after the death of the animal.Lawrie, 159. One source of infectious organisms is
bacteraemia Bloodstream infections (BSIs), which include bacteremias when the infections are bacterial and fungemias when the infections are fungal, are infections present in the blood. Blood is normally a sterile environment, so the detection of micro ...
, the presence of bacteria in the blood of slaughtered animals. The
large intestine The large intestine, also known as the large bowel, is the last part of the gastrointestinal tract and of the digestive system in tetrapods. Water is absorbed here and the remaining waste material is stored in the rectum as feces before being r ...
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 A captive bolt (also variously known as a cattle gun, stunbolt gun, bolt gun, or stunner) is a device used for stunning animals prior to slaughter. The goal of captive bolt stunning is to inflict a forceful strike on the forehead with the b ...
's bolt alone may carry about 400,000 bacteria per square centimeter.Lawrie, 160. After slaughter, care must be taken not to infect the meat through contact with any of the various sources of infection in the
abattoir A slaughterhouse, also called abattoir (), is a facility where animals are slaughtered to provide food. Slaughterhouses supply meat, which then becomes the responsibility of a packaging facility. Slaughterhouses that produce meat that is no ...
, notably the hides and soil adhering to them, water used for washing and cleaning, the dressing implements and the slaughterhouse personnel. Bacterial
genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...
commonly infecting meat while it is being processed, cut, packaged, transported, sold and handled include
Salmonella ''Salmonella'' is a genus of rod-shaped (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. The two species of ''Salmonella'' are ''Salmonella enterica'' and ''Salmonella bongori''. ''S. enterica'' is the type species and is fur ...
spp.,
Shigella ''Shigella'' is a genus of bacteria that is Gram-negative, facultative anaerobic, non-spore-forming, nonmotile, rod-shaped, and genetically closely related to ''E. coli''. The genus is named after Kiyoshi Shiga, who first discovered it in 1897. ...
spp.,
E. coli ''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Escher ...
, B. proteus,
S. epidermidis ''Staphylococcus epidermidis'' is a Gram-positive bacterium, and one of over 40 species belonging to the genus ''Staphylococcus''. It is part of the normal human microbiota, typically the skin microbiota, and less commonly the mucosal microbiot ...
and
Staph. aureus ''Staphylococcus aureus'' is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often positive ...
, Cl. welchii, B. cereus and faecal
streptococci ''Streptococcus'' is a genus of gram-positive ' (plural ) or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria), in the phylum Bacillota. Cell division in streptococci occurs ...
.Lawrie, 163. These bacteria are all commonly carried by humans; infectious bacteria from the soil include Cl. botulinum. Among the
mold A mold () or mould () is one of the structures certain fungus, fungi can form. The dust-like, colored appearance of molds is due to the formation of Spore#Fungi, spores containing Secondary metabolite#Fungal secondary metabolites, fungal seco ...
s commonly infecting meat are
Penicillium ''Penicillium'' () is a genus of ascomycetous fungi that is part of the mycobiome of many species and is of major importance in the natural environment, in food spoilage, and in food and drug production. Some members of the genus produce pe ...
,
Mucor ''Mucor'' is a microbial genus of approximately 40 species of molds in the family Mucoraceae. Species are commonly found in soil, digestive systems, plant surfaces, some cheeses like Tomme de Savoie, rotten vegetable matter and iron oxide resid ...
,
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. Many species ...
,
Alternaria ''Alternaria'' is a genus of Deuteromycetes fungi. All 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. They ...
, Sporotrichium and
Thamnidium ''Thamnidium'' is a genus of fungi belonging to the family Mucoraceae. The genus was circumscribed in 1809 by Johann Heinrich Friedrich Link. ''Thamnidium'' molds are key participants in the aging process for dry aged beef, producing protease ...
.Lawrie, 161. As these microorganisms colonize a piece of meat, they begin to break it down, leaving behind
toxin A toxin is a naturally occurring organic poison produced by metabolic activities of living cells or organisms. Toxins occur especially as a protein or conjugated protein. The term toxin was first used by organic chemist Ludwig Brieger (1849– ...
s that can cause
enteritis Enteritis is inflammation of the small intestine. It is most commonly caused by food or drink contaminated with pathogenic microbes,Dugdale, David C., IIII, and George F Longretc"Enteritis" MedlinePlus Medical Encyclopedia, 18 October 2008. Access ...
or
food poisoning Foodborne illness (also foodborne disease and food poisoning) is any illness resulting from the spoilage of contaminated food by pathogenic bacteria, viruses, or parasites that contaminate food, as well as prions (the agents of mad cow disease) ...
, potentially lethal in the rare case of
botulism Botulism is a rare and potentially fatal illness caused by a toxin produced by the bacterium ''Clostridium botulinum''. The disease begins with weakness, blurred vision, feeling tired, and trouble speaking. This may then be followed by weaknes ...
. The microorganisms do not survive a thorough
cooking Cooking, cookery, or culinary arts is the art, science and craft of using heat to Outline of food preparation, prepare food for consumption. Cooking techniques and ingredients vary widely, from grilling food over an open fire to using electric ...
of the meat, but several of their toxins and microbial
spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...
s do. The microbes may also infect the person eating the meat, although against this the
microflora Microbiota are the range of microorganisms that may be commensal, symbiotic, or pathogenic found in and on all multicellular organisms, including plants. Microbiota include bacteria, archaea, protists, fungi, and viruses, and have been found to ...
of the human gut 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 safety Food safety (or food hygiene) is used as a scientific method/discipline describing handling, preparation, and storage of food in ways that prevent food-borne illness. The occurrence of two or more cases of a similar illness resulting from t ...
.Lawrie, 165. 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 A bacteriophage (), also known informally as a ''phage'' (), is a duplodnaviria virus that infects and replicates within bacteria and archaea. The term was derived from "bacteria" and the Greek φαγεῖν ('), meaning "to devour". Bacterio ...
and serological typing, direct
epifluorescence A fluorescence microscope is an optical microscope that uses fluorescence instead of, or in addition to, scattering, reflection, and attenuation or absorption, to study the properties of organic or inorganic substances. "Fluorescence microsc ...
filter techniques ( DEFT) and plasmid profiling.


Symptoms


Microbial spoilage

Depending on oxygen availability, meat spoilage by micro-organisms can manifest itself as follows:Table adapted from Lawrie, 166.


Notes


References

* {{DEFAULTSORT:Meat Food preservation Food storage