Meat spoilage

Last updated

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.

Contents

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"). [1] There are numerous diseases that humans may contract from endogenously infected meat, such as anthrax, bovine tuberculosis, brucellosis, salmonellosis, listeriosis, trichinosis or taeniasis. [2]

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. [3] 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, [3] 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. [4] 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. [4]

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. [5] These bacteria are all commonly carried by humans; infectious bacteria from the soil include Cl. botulinum. [5] Among the molds commonly infecting meat are Penicillium, Mucor, Cladosporium, Alternaria, Sporotrichium and Thamnidium. [6]

As these microorganisms colonize a piece of meat, they begin to break it down, leaving behind toxins that can cause enteritis or food poisoning, potentially lethal in the rare case of botulism. [5] The microorganisms do not survive a thorough cooking of the meat, but several of their toxins and microbial spores do. [5] The microbes may also infect the person eating the meat, although against this the microflora of the human gut is normally an effective barrier. [5]

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. [7] 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. [7]

Symptoms

Microbial spoilage

Depending on oxygen availability, meat spoilage by micro-organisms can manifest itself as follows: [8]

OxygenMicrobial agentSymptoms
Present Aerobic bacteria
  • Surface slime
  • Discolouration
  • Gas production
  • Change in odor
  • Fat decomposition
Present Yeasts
  • Surface slime
  • Discoloration
  • Change in odor and taste
  • Fat decomposition
Present Molds
  • Sticky and "whiskery" surface
  • Discoloration
  • Change in odor
  • Fat decomposition
Absent Anaerobic bacteria

Notes

  1. ↑ Lawrie, 157.
  2. ↑ Lawrie, 158.
  3. 1 2 Lawrie, 159.
  4. 1 2 Lawrie, 160.
  5. 1 2 3 4 5 Lawrie, 163.
  6. ↑ Lawrie, 161.
  7. 1 2 Lawrie, 165.
  8. ↑ Table adapted from Lawrie, 166.

Related Research Articles

<span class="mw-page-title-main">Food preservation</span> Inhibition of microbial growth in food

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 visual deterioration, such as the enzymatic browning reaction in apples after they are cut during food preparation. By preserving food, food waste can be reduced, which is an important way to decrease production costs and increase the efficiency of food systems, improve food security and nutrition and contribute towards environmental sustainability. For instance, it can reduce the environmental impact of food production.

<span class="mw-page-title-main">Microorganism</span> Microscopic living organism

A microorganism, or microbe, is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells.

A human pathogen is a pathogen that causes disease in humans.

<span class="mw-page-title-main">Infection</span> Invasion of an organisms body by pathogenic agents

An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable disease, is an illness resulting from an infection.

<i>Campylobacter</i> Genus of Gram-negative bacteria

Campylobacter is a genus of Gram-negative bacteria. Campylobacter typically appear comma- or s-shaped, and are motile. Some Campylobacter species can infect humans, sometimes causing campylobacteriosis, a diarrhoeal disease in humans. Campylobacteriosis is usually self-limiting and antimicrobial treatment is often not required, except in severe cases or immunocompromised patients. The most known source for Campylobacter is poultry, but due to their diverse natural reservoir, Campylobacter spp. can also be transmitted via water. Other known sources of Campylobacter infections include food products, such as unpasteurised milk and contaminated fresh produce. Sometimes the source of infection can be direct contact with infected animals, which often carry Campylobacter asymptomatically. At least a dozen species of Campylobacter have been implicated in human disease, with C. jejuni (80–90%) and C. coli (5-10%) being the most common. C. jejuni is recognized as one of the main causes of bacterial foodborne disease in many developed countries. It is the number one cause of bacterial gastroenteritis in Europe, with over 246,000 cases confirmed annually. C. jejuni infection can also cause bacteremia in immunocompromised people, while C. lari is a known cause of recurrent diarrhea in children. C. fetus can cause spontaneous abortions in cattle and sheep, and is an opportunistic pathogen in humans.

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.

<span class="mw-page-title-main">Foodborne illness</span> Illness from eating spoiled food

Foodborne illness is any illness resulting from the spoilage of contaminated food by pathogenic bacteria, viruses, or parasites that contaminate food, as well as prions, and toxins such as aflatoxins in peanuts, poisonous mushrooms, and various species of beans that have not been boiled for at least 10 minutes.

<span class="mw-page-title-main">Microbiological culture</span> Method of allowing microorganisms to multiply in a controlled medium

A microbiological culture, or microbial culture, is a method of multiplying microbial organisms by letting them reproduce in predetermined culture medium under controlled laboratory conditions. Microbial cultures are foundational and basic diagnostic methods used as a research tool in molecular biology.

Exogenous bacteria are microorganisms introduced to closed biological systems from the external world. They exist in aquatic and terrestrial environments, as well as the atmosphere. Microorganisms in the external environment have existed on Earth for 3.5 billion years. Exogenous bacteria can be either benign or pathogenic. Pathogenic exogenous bacteria can enter a closed biological system and cause disease such as Cholera, which is induced by a waterborne microbe that infects the human intestine. Exogenous bacteria can be introduced into a closed ecosystem as well, and have mutualistic benefits for both the microbe and the host. A prominent example of this concept is bacterial flora, which consists of exogenous bacteria ingested and endogenously colonized during the early stages of life. Bacteria that are part of normal internal ecosystems, also known as bacterial flora, are called Endogenous Bacteria. A significant amount of prominent diseases are induced by exogenous bacteria such as gonorrhea, meningitis, tetanus, and syphilis. Pathogenic exogenous bacteria can enter a host via cutaneous transmission, inhalation, and consumption.

<span class="mw-page-title-main">Food microbiology</span> Study of the microorganisms that inhibit, create, or contaminate food

Food microbiology is the study of the microorganisms that inhabit, create, or contaminate food. This includes the study of microorganisms causing food spoilage; pathogens that may cause disease ; microbes used to produce fermented foods such as cheese, yogurt, bread, beer, and wine; and microbes with other useful roles, such as producing probiotics.

<span class="mw-page-title-main">Medical microbiology</span> Branch of medical science

Medical microbiology, the large subset of microbiology that is applied to medicine, is a branch of medical science concerned with the prevention, diagnosis and treatment of infectious diseases. In addition, this field of science studies various clinical applications of microbes for the improvement of health. There are four kinds of microorganisms that cause infectious disease: bacteria, fungi, parasites and viruses, and one type of infectious protein called prion.

Campylobacter upsaliensis is a gram negative bacteria in the Campylobacter genus. C. upsaliensis is found worldwide, and is a common cause of campylobacteriosis in humans, as well as gastroenteritis in dogs. Human infections are primarily associated with raw or undercooked meat and contaminated water sources, however there is some zoonotic risk associated with the spread from dogs. C. upsaliensis primarily affects the gastrointestinal tract as it damages gastrointestinal epithelial cells. There are many methods for detecting C.upsaliensis including PCR and ELISA, however there is no current gold standard in detection techniques. Infection is typically self limiting, however there is antimicrobial therapy available.

Enteroinvasive Escherichia coli (EIEC) is a type of pathogenic bacteria whose infection causes a syndrome that is identical to shigellosis, with profuse diarrhea and high fever. EIEC are highly invasive, and they use adhesin proteins to bind to and enter intestinal cells. They produce no toxins, but severely damage the intestinal wall through mechanical cell destruction.

Anaerobic infections are caused by anaerobic bacteria. Obligately anaerobic bacteria do not grow on solid media in room air ; facultatively anaerobic bacteria can grow in the presence or absence of air. Microaerophilic bacteria do not grow at all aerobically or grow poorly, but grow better under 10% carbon dioxide or anaerobically. Anaerobic bacteria can be divided into strict anaerobes that can not grow in the presence of more than 0.5% oxygen and moderate anaerobic bacteria that are able of growing between 2 and 8% oxygen. Anaerobic bacteria usually do not possess catalase, but some can generate superoxide dismutase which protects them from oxygen.

<span class="mw-page-title-main">Biopreservation</span>

Biopreservation is the use of natural or controlled microbiota or antimicrobials as a way of preserving food and extending its shelf life. The biopreservation of food, especially utilizing lactic acid bacteria (LAB) that are inhibitory to food spoilage microbes, has been practiced since early ages, at first unconsciously but eventually with an increasingly robust scientific foundation. Beneficial bacteria or the fermentation products produced by these bacteria are used in biopreservation to control spoilage and render pathogens inactive in food. There are a various modes of action through which microorganisms can interfere with the growth of others such as organic acid production, resulting in a reduction of pH and the antimicrobial activity of the un-dissociated acid molecules, a wide variety of small inhibitory molecules including hydrogen peroxide, etc. It is a benign ecological approach which is gaining increasing attention.

<span class="mw-page-title-main">Food spoilage</span> Often due to bacteria and fungi

Food spoilage is the process where a food product becomes unsuitable to ingest by the consumer. The cause of such a process is due to many outside factors as a side-effect of the type of product it is, as well as how the product is packaged and stored. Due to food spoilage, one-third of the world's food produced for the consumption of humans is lost every year. Bacteria and various fungi are the cause of spoilage and can create serious consequences for the consumers, but there are preventive measures that can be taken.

In biology, a pathogen in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ.

The host–pathogen interaction is defined as how microbes or viruses sustain themselves within host organisms on a molecular, cellular, organismal or population level. This term is most commonly used to refer to disease-causing microorganisms although they may not cause illness in all hosts. Because of this, the definition has been expanded to how known pathogens survive within their host, whether they cause disease or not.

Campylobacter coli is a Gram-negative, microaerophilic, non-endospore-forming, S-shaped bacterial species within genus Campylobacter. In humans, it C. coli can cause campylobacteriosis, a diarrhoeal disease which is the most frequently reported foodborne illness in the European Union. C. coli grows slowly with an optimum temperature of 42 °C. When exposed to air for long periods, they become spherical or coccoid shaped.

Enteroaggregative Escherichia coli are a pathotype of Escherichia coli which cause acute and chronic diarrhea in both the developed and developing world. They may also cause urinary tract infections. EAEC are defined by their "stacked-brick" pattern of adhesion to the human laryngeal epithelial cell line HEp-2. The pathogenesis of EAEC involves the aggregation of and adherence of the bacteria to the intestinal mucosa, where they elaborate enterotoxins and cytotoxins that damage host cells and induce inflammation that results in diarrhea.

References

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.