Spoiled Food
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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.


Bacteria

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 ...
are responsible for some of the spoilage of food. When bacteria breaks down the food,
acid In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...
s and other waste products are generated in the process. While the bacteria itself may or may not be harmful, the waste products may be unpleasant to taste or may even be harmful to one's health. There are two types of pathogenic bacteria that target different categories of food. The first type is called ''
Clostridium botulinum ''Clostridium botulinum'' is a Gram-positive, rod-shaped, anaerobic, spore-forming, motile bacterium with the ability to produce the neurotoxin botulinum. The botulinum toxin can cause botulism, a severe flaccid paralytic disease in humans an ...
'' and targets food such as meat and poultry, and ''
Bacillus cereus ''Bacillus cereus'' is a Gram-positive rod-shaped bacterium commonly found in soil, food, and marine sponges. The specific name, ''cereus'', meaning "waxy" in Latin, refers to the appearance of colonies grown on blood agar. Some strains are ha ...
'', which targets milk and cream. When stored or subjected to unruly conditions, the organisms will begin to breed apace, releasing harmful
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 severe illness, even when cooked safely.


Fungi

''
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 ...
'' have been seen as a method of food spoilage, causing only an undesirable appearance to food, however, there has been significant evidence of various fungi being a cause of death of many people spanning across hundreds of years in many places through the world. Fungi are caused by acidifying, fermenting, discoloring and disintegrating processes and can create fuzz, powder and slimes of many different colors, including black, white, red, brown and green. ''Mold'' is a type of fungus, but the two terms are not reciprocal of each other; they have their own defining features and perform their own tasks. Very well known types of mold are
Aspergillus ' () is a genus consisting of several hundred mold species found in various climates worldwide. ''Aspergillus'' was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli. Viewing the fungi under a microscope, Miche ...
and
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 ...
, and, like regular fungi, create a fuzz, powder and slime of various colors. ''Yeast'' is also a type of fungus that grows vegetatively via single cells that either bud or divide by way of fission, allowing for yeast to multiply in liquid environments favoring the dissemination of single celled microorganisms. Yeast forms mainly in liquid environments and anaerobic conditions, but being single celled, it oftentimes cannot spread on or into solid surfaces where other fungus flourish. Yeast also produces at a slower rate than bacteria, therefore being at a disadvantage in environments where bacteria are.
Yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitut ...
s can be responsible for the decomposition of food with a high sugar content. The same effect is useful in the production of various types of food and beverages, such as
bread Bread is a staple food prepared from a dough of flour (usually wheat) and water, usually by baking. Throughout recorded history and around the world, it has been an important part of many cultures' diet. It is one of the oldest human-made f ...
,
yogurt Yogurt (; , from tr, yoğurt, also spelled yoghurt, yogourt or yoghourt) is a food produced by bacterial Fermentation (food), fermentation of milk. The bacteria used to make yogurt are known as ''yogurt cultures''. Fermentation of sugars in t ...
,
cider Cider ( ) is an alcoholic beverage made from the fermented juice of apples. Cider is widely available in the United Kingdom (particularly in the West Country) and the Republic of Ireland. The UK has the world's highest per capita consumption, ...
, and
alcoholic beverage An alcoholic beverage (also called an alcoholic drink, adult beverage, or a drink) is a drink that contains ethanol, a type of alcohol that acts as a drug and is produced by fermentation of grains, fruits, or other sources of sugar. The c ...
s.


Signs

Signs of food spoilage may include an appearance different from the food in its fresh form, such as a change in color, a change in texture, an
unpleasant odour An odor (American English) or odour (Commonwealth English; see spelling differences) is caused by one or more volatilized chemical compounds that are generally found in low concentrations that humans and animals can perceive via their sense ...
, or an undesirable
taste The gustatory system or sense of taste is the sensory system that is partially responsible for the perception of taste (flavor). Taste is the perception produced or stimulated when a substance in the mouth reacts chemically with taste receptor ...
. The item may become softer than normal. If mold occurs, it is often visible externally on the item.


Consequences

Spoilage bacteria do not normally cause "
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) ...
"; typically, the microorganisms that cause
foodborne illness 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) ...
es are odorless and flavourless, and otherwise undetectable outside the lab. Eating deteriorated food could not be considered safe due to
mycotoxins A mycotoxin (from the Greek μύκης , "fungus" and τοξίνη , "toxin") is a toxic secondary metabolite produced by organisms of kingdom Fungi and is capable of causing disease and death in both humans and other animals. The term 'mycotoxin' ...
or microbial wastes. Some pathogenic bacteria, such as ''
Clostridium perfringens ''Clostridium perfringens'' (formerly known as ''C. welchii'', or ''Bacillus welchii'') is a Gram-positive, rod-shaped, anaerobic, spore-forming pathogenic bacterium of the genus '' Clostridium''. ''C. perfringens'' is ever-present in nature an ...
'' and ''
Bacillus cereus ''Bacillus cereus'' is a Gram-positive rod-shaped bacterium commonly found in soil, food, and marine sponges. The specific name, ''cereus'', meaning "waxy" in Latin, refers to the appearance of colonies grown on blood agar. Some strains are ha ...
'', are capable of causing spoilage. Issues of food spoilage do not necessarily have to do with the quality of the food, but more so with the safety of consuming said food. However, there are cases where food has been proven to contain toxic ingredients. 200 years ago, Claviceps purpurea, a type of fungus, was linked to human diseases and 100 years ago in Japan, yellow rice was found to contain toxic ingredients.


Prevention

A number of methods of prevention can be used that can either totally prevent, delay, or otherwise reduce food spoilage. A
food rotation system Stock rotation is a way of mitigating stock loss. It is the practice, used in hospitality and retail, especially in food stores such as restaurants and supermarkets, of moving products with an earlier sell-by date to the front of a shelf (or in t ...
uses the first in first out method (FIFO), which ensures that the first item purchased is the first item consumed.
Preservative A preservative is a substance or a chemical that is added to products such as food products, beverages, pharmaceutical drugs, paints, biological samples, cosmetics, wood, and many other products to prevent decomposition by microbial growth or by ...
s can expand the
shelf life Shelf life is the length of time that a commodity may be stored without becoming unfit for use, consumption, or sale. In other words, it might refer to whether a commodity should no longer be on a pantry shelf (unfit for use), or no longer on a ...
of food and can lengthen the time long enough for it to be harvested, processed, sold, and kept in the consumer's home for a reasonable length of time. One of the age old techniques for food preservation, to avoid mold and fungus growth, is the process of drying out the food or dehydrating it. While there is a chance of it developing a fungus targeted towards dried food products, the chances are quite low. Other than drying, other methods include salting, curing, canning, refrigeration, freezing, preservatives, irradiation, and high hydrostatic pressure:
Refrigeration The term refrigeration refers to the process of removing heat from an enclosed space or substance for the purpose of lowering the temperature.International Dictionary of Refrigeration, http://dictionary.iifiir.org/search.phpASHRAE Terminology, ht ...
can increase the shelf life of certain foods and beverages, though with most items, it does not indefinitely expand it. Freezing can preserve food even longer, though even freezing has limitations.
Canning Canning is a method of food preservation in which food is processed and sealed in an airtight container (jars like Mason jars, and steel and tin cans). Canning provides a shelf life that typically ranges from one to five years, although u ...
of food can preserve food for a particularly long period of time, whether done at home or commercially. Canned food is
vacuum pack Vacuum packing is a method of packaging that removes air from the package prior to sealing. This method involves placing items in a plastic film package, removing air from inside and sealing the package. Shrink film is sometimes used to have a tig ...
ed in order to keep oxygen, which is needed by bacteria in aerobic spoilage, out of the can. Canning does have limitations, and does not preserve the food indefinitely.
Lactic acid fermentation Lactic acid fermentation is a metabolic process by which glucose or other six-carbon sugars (also, disaccharides of six-carbon sugars, e.g. sucrose or lactose) are converted into cellular energy and the metabolite lactate, which is lactic acid ...
also preserves food and prevents spoilage. Food like meat, poultry, milk and cream should be kept out of the Danger Zone (between ). Anything between that range is considered dangerous and can cause pathogenic toxins to be emitted, resulting in severe illness in the consumer. Another way to keep food from spoiling is by following a four step system: Clean, Separate, Cook, Chill.


See also

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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 ...
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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 ...
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Food grading Food grading involves the inspection, assessment and sorting of various foods regarding quality, freshness, legal conformity and market value.Saravacos, George D.; Maroulis, Zacharias B. (2011''Food Process Engineering Operations'' CRC Press. p ...
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Foodborne illness 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) ...
*
Shelf life Shelf life is the length of time that a commodity may be stored without becoming unfit for use, consumption, or sale. In other words, it might refer to whether a commodity should no longer be on a pantry shelf (unfit for use), or no longer on a ...


References

{{reflist Food safety Food preservation Food waste