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Food preservation includes processes that make
food more resistant to
microorganism
A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
growth and slow the
oxidation
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...
of
fat
In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food.
The term often refers specifically to triglycerides (triple est ...
s. This slows down the
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 ...
and
rancidification
Rancidification is the process of complete or incomplete autoxidation or hydrolysis of fats and oils when exposed to air, light, moisture, or bacterial action, producing short-chain aldehydes, ketones and free fatty acids.
When these processes o ...
process. Food preservation may also include processes that inhibit visual deterioration, such as the
enzymatic browning
Browning is the process of food turning brown due to the chemical reactions that take place within. The process of browning is one of the chemical reactions that take place in food chemistry and represents an interesting research topic regardin ...
reaction in apples after they are cut during food preparation. By preserving
food,
food waste
Food loss and waste is food that is not eaten. The causes of food waste or loss are numerous and occur throughout the food system, during production, processing, distribution, retail and food service sales, and consumption. Overall, about o ...
can be reduced, which is an important way to decrease production costs and increase the efficiency of
food systems, improve
food security
Food security speaks to the availability of food in a country (or geography) and the ability of individuals within that country (geography) to access, afford, and source adequate foodstuffs. According to the United Nations' Committee on World ...
and
nutrition
Nutrition is the biochemical and physiological process by which an organism uses food to support its life. It provides organisms with nutrients, which can be metabolized to create energy and chemical structures. Failure to obtain sufficient ...
and contribute towards environmental sustainability. For instance, it can reduce the
environmental impact of food production.
Many processes designed to preserve food involve more than one food preservation method. Preserving fruit by turning it into jam, for example, involves boiling (to reduce the fruit's moisture content and to kill bacteria, etc.), sugaring (to prevent their re-growth) and sealing within an airtight jar (to prevent recontamination).
Different food preservation methods have different impacts on the quality of the food and food systems. Some traditional methods of preserving food have been shown to have a lower
energy input and
carbon footprint compared to modern methods.
Some methods of food preservation are known to create
carcinogen
A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive subs ...
s. In 2015, the
International Agency for Research on Cancer
The International Agency for Research on Cancer (IARC; french: Centre International de Recherche sur le Cancer, CIRC) is an intergovernmental agency forming part of the World Health Organization of the United Nations.
Its role is to conduct and ...
of the
World Health Organization
The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of ...
classified
processed meat
Processed meat is considered to be any meat which has been modified in order to either improve its taste or to extend its shelf life. Methods of meat processing include salting, curing, fermentation, smoking, and/or the addition of chemical pr ...
, i.e., meat that has undergone salting, curing, fermenting, and smoking, as "
carcinogenic
A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive subs ...
to humans."
Traditional techniques
Some techniques of food preservation pre-date the
dawn of agriculture. Others were discovered more recently.
Boiling
Boiling liquids can kill any existing microbes. Milk and water are often boiled to kill any harmful microbes that may be present in them.
Burial
Burial of food can preserve it due to a variety of factors: lack of light, lack of oxygen, cool temperatures, pH level, or
desiccants in the soil. Burial may be combined with other methods such as salting or fermentation. Most foods can be preserved in soil that is very dry and salty (thus a desiccant) such as sand, or soil that is frozen.
Many
root vegetables
Root vegetables are underground plant parts eaten by humans as food. Although botany distinguishes true roots (such as taproots and tuberous roots) from non-roots (such as bulbs, corms, rhizomes, and tubers, although some contain both hypocotyl ...
are very resistant to spoilage and require no other preservation than storage in cool dark conditions, for example by burial in the ground, such as in a
storage clamp (not to be confused with a
root cellar). Cabbage was traditionally buried during Autumn in northern US farms for preservation. Some methods keep it crispy while other methods produce
sauerkraut
Sauerkraut (; , "sour cabbage") is finely cut raw cabbage that has been fermented by various lactic acid bacteria. It has a long shelf life and a distinctive sour flavor, both of which result from the lactic acid formed when the bacteria ferm ...
. A similar process is used in the traditional production of
kimchi
''Kimchi'' (; ko, 김치, gimchi, ), is a traditional Korean side dish of salted and fermented vegetables, such as napa cabbage and Korean radish. A wide selection of seasonings are used, including '' gochugaru'' (Korean chili powder), ...
.
Sometimes meat is buried under conditions that cause preservation. If buried on hot coals or ashes, the heat can kill pathogens, the dry ash can desiccate, and the earth can block oxygen and further contamination. If buried where the earth is very cold, the earth acts like a refrigerator, or, in areas of
permafrost, a freezer.
In
Orissa, India
Odisha (English: , ), formerly Orissa ( the official name until 2011), is an Indian state located in Eastern India. It is the 8th largest state by area, and the 11th largest by population. The state has the third largest population of ...
, it is practical to store rice by burying it underground. This method helps to store for three to six months during the dry season.
Butter and similar substances have been preserved as
bog butter in Irish
peat bogs
A bog or bogland is a wetland that accumulates peat as a deposit of dead plant materials often mosses, typically sphagnum moss. It is one of the four main types of wetlands. Other names for bogs include mire, mosses, quagmire, and muskeg ...
for centuries.
Century eggs are traditionally created by placing eggs in alkaline mud (or other alkaline substance), resulting in their "inorganic" fermentation through raised pH instead of spoiling. The fermentation preserves them and breaks down some of the complex, less flavorful proteins and fats into simpler, more flavorful ones.
Canning
Canning involves cooking food, sealing it in sterilized cans or jars, and
boiling the containers to kill or weaken any remaining bacteria as a form of
sterilization. It was invented by the French confectioner
Nicolas Appert
Nicolas Appert (17 November 1749 – 1 June 1841) was the French inventor of airtight food preservation. Appert, known as the "father of Food Science", was a confectioner. Appert described his invention as a way "of conserving all kinds of food ...
. By 1806, this process was used by the French Navy to preserve meat, fruit, vegetables, and even milk. Although Appert had discovered a new way of preservation, it was not understood until 1864 when
Louis Pasteur found the relationship between microorganisms, food spoilage, and illness.
Foods have varying degrees of natural protection against spoilage and may require that the final step occur in a
pressure cooker
Pressure cooking is the process of cooking food under high pressure steam and water or a water-based cooking liquid, in a sealed vessel known as a ''pressure cooker''. High pressure limits boiling, and creates higher cooking temperatures which ...
. High-acid fruits like
strawberries require no preservatives to can and only a short boiling cycle, whereas marginal vegetables such as
carrots require longer boiling and addition of other acidic elements. Low-acid foods, such as vegetables and meats, require pressure canning. Food preserved by canning or bottling is at immediate risk of spoilage once the can or bottle has been opened.
Lack of quality control in the canning process may allow ingress of water or micro-organisms. Most such failures are rapidly detected as decomposition within the can causes gas production and the can will swell or burst. However, there have been examples of poor manufacture (underprocessing) and poor
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 ...
allowing contamination of canned food by the obligate
anaerobe ''
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 ...
'', which produces an acute toxin within the food, leading to severe illness or death. This organism produces no gas or obvious taste and remains undetected by taste or smell. Its toxin is denatured by cooking, however. Cooked
mushroom
A mushroom or toadstool is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground, on soil, or on its food source. ''Toadstool'' generally denotes one poisonous to humans.
The standard for the name "mushroom" is ...
s, when handled poorly and then canned, can support the growth of ''
Staphylococcus aureus'', which produces a toxin that is not destroyed by canning or subsequent reheating.
Confit
Meat can be preserved by salting it, cooking it at or near in some kind of fat (such as
lard or
tallow
Tallow is a rendered form of beef or mutton fat, primarily made up of triglycerides.
In industry, tallow is not strictly defined as beef or mutton fat. In this context, tallow is animal fat that conforms to certain technical criteria, includ ...
), and then storing it immersed in the fat. These preparations were popular in Europe before refrigerators became ubiquitous. They are still popular in France, where the term originates.
[Bruce Aidells (2012): ]
The Great Meat Cookbook
', page 429. Houghton Mifflin Harcourt; 632 pages. [Susan Jung (2012):]
Truc: confit, a fat-fabulous way to preserve meat
. ''Post Magazine'', online article, posted on 2012-11-03, accessed 2019-02-21. The preparation will keep longer if stored in a cold cellar or buried in cold ground.
Cooling
Cooling
Cooling is removal of heat, usually resulting in a lower temperature and/or phase change. Temperature lowering achieved by any other means may also be called cooling.ASHRAE Terminology, https://www.ashrae.org/technical-resources/free-resources/as ...
preserves food by slowing down the growth and reproduction of microorganisms and the action of enzymes that causes the food to rot. The introduction of commercial and domestic refrigerators drastically improved the diets of many in the
Western world
The Western world, also known as the West, primarily refers to the various nations and states in the regions of Europe, North America, and Oceania. by allowing food such as fresh fruit, salads and dairy products to be stored safely for longer periods, particularly during warm weather.
Before the era of mechanical refrigeration, cooling for food storage occurred in the forms of
root cellars and
icebox
An icebox (also called a cold closet) is a compact non-mechanical refrigerator which was a common early-twentieth-century kitchen appliance before the development of safely powered refrigeration devices. Before the development of electric refrige ...
es. Rural people often did their own
ice cutting
Ice cutting is a winter task of collecting surface ice from lakes and rivers for storage in ice houses and use or sale as a cooling method. Rare today, it was common (see ice trade) before the era of widespread mechanical refrigeration and air ...
, whereas town and city dwellers often relied on the
ice trade
The ice trade, also known as the frozen water trade, was a 19th-century and early-20th-century industry, centering on the east coast of the United States and Norway, involving the large-scale harvesting, transport and sale of natural ice, an ...
. Today, root cellaring remains popular among people who value various goals, including
local food
Local food is food that is produced within a short distance of where it is consumed, often accompanied by a social structure and supply chain different from the large-scale supermarket system.
Local food (or "locavore") movements aim to con ...
,
heirloom crops, traditional home
cooking techniques
This is a list of cooking techniques commonly used in cooking and food preparation.
Cooking is the art of preparing food for ingestion, commonly with the application of heat. Cooking techniques and ingredients vary widely across the world, refle ...
,
family farming,
frugality
Frugality is the quality of being frugal, sparing, thrifty, prudent or economical in the consumption of consumable resources such as food, time or money, and avoiding waste, lavishness or extravagance.
In behavioral science, frugality has been ...
,
self-sufficiency,
organic farming
Organic farming, also known as ecological farming or biological farming,Labelling, article 30 o''Regulation (EU) 2018/848 of the European Parliament and of the Council of 30 May 2018 on organic production and labelling of organic products and re ...
, and others.
Curing
![Prague powder No 1](https://upload.wikimedia.org/wikipedia/commons/c/cd/Prague_powder_No_1.jpg)
The earliest form of curing was dehydration or
drying
Drying is a mass transfer process consisting of the removal of water or another solvent by evaporation from a solid, semi-solid or liquid. This process is often used as a final production step before selling or packaging products. To be consider ...
, used as early as 12,000BC.
Smoking and
salting techniques improve on the drying process and add antimicrobial agents that aid in preservation. Smoke deposits a number of pyrolysis products onto the food, including the
phenol
Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it ...
s
syringol
Syringol is the organic compound with the formula HO(CH3O)2C6H3. The molecule is a phenol, with methoxy groups in the flanking (2 and 6) positions. It is the symmetrically dimethylated derivative of pyrogallol. It is a colorless solid, althou ...
,
guaiacol
Guaiacol () is an organic compound with the formula C6H4(OH)(OCH3). It is a phenolic compound containing an methoxy functional group. Guaiacol appears as a viscous colorless oil, although aged or impure samples are often yellowish. It occurs wid ...
and
catechol
Catechol ( or ), also known as pyrocatechol or 1,2-dihydroxybenzene, is a toxic organic compound with the molecular formula . It is the ''ortho'' isomer of the three isomeric benzenediols. This colorless compound occurs naturally in trace amoun ...
.
[Msagati, T. (2012). "The Chemistry of Food Additives and Preservatives"] Salt accelerates the drying process using
osmosis
Osmosis (, ) is the spontaneous net movement or diffusion of solvent molecules through a selectively-permeable membrane from a region of high water potential (region of lower solute concentration) to a region of low water potential (region o ...
and also inhibits the growth of several common strains of bacteria. More recently
nitrites have been used to cure meat, contributing a characteristic pink colour.
Fermentation
Some foods, such as many
cheeses,
wine
Wine is an alcoholic drink typically made from fermented grapes. Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different varieties of grapes and strains of yeasts are m ...
s, and
beer
Beer is one of the oldest and the most widely consumed type of alcoholic drink in the world, and the third most popular drink overall after water and tea. It is produced by the brewing and fermentation of starches, mainly derived from ce ...
s, use specific micro-organisms that combat spoilage from other less-benign organisms. These micro-organisms keep pathogens in check by creating an environment toxic for themselves and other micro-organisms by producing acid or alcohol. Methods of fermentation include, but are not limited to, starter micro-organisms, salt, hops, controlled (usually cool) temperatures and controlled (usually low) levels of oxygen. These methods are used to create the specific controlled conditions that will support the desirable organisms that produce food fit for human consumption.
Fermentation is the microbial conversion of starch and sugars into alcohol. Not only can fermentation produce alcohol, but it can also be a valuable preservation technique. Fermentation can also make foods more nutritious and palatable. For example, drinking water in the Middle Ages was dangerous because it often contained pathogens that could spread disease. When the water is made into beer, the boiling during the brewing process kills any bacteria in the water that could make people sick. Additionally, the water now has the nutrients from the barley and other ingredients, and the microorganisms can also produce vitamins as they ferment.
Freezing
Freezing
Freezing is a phase transition where a liquid turns into a solid when its temperature is lowered below its freezing point. In accordance with the internationally established definition, freezing means the solidification phase change of a liquid ...
is also one of the most commonly used processes, both commercially and domestically, for preserving a very wide range of foods, including prepared foods that would not have required freezing in their unprepared state. For example, potato waffles are stored in the freezer, but potatoes themselves require only a cool dark place to ensure many months' storage. Cold stores provide large-volume, long-term storage for strategic food stocks held in case of national emergency in many countries.
Heating
Heating to temperatures which are sufficient to kill microorganisms inside the food is a method used with
perpetual stew
A perpetual stew, also known as forever soup, hunter's pot or hunter's stew, is a pot into which whatever foodstuffs one can find is placed and cooked. The pot is never or rarely emptied all the way, and ingredients and liquid are replenished as ...
s.
Jellying
Food may be preserved by cooking in a material that solidifies to form a gel. Such materials include
gelatin,
agar,
maize
Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. The ...
flour, and
arrowroot
Arrowroot is a starch obtained from the rhizomes (rootstock) of several tropical plants, traditionally ''Maranta arundinacea'', but also Florida arrowroot from ''Zamia integrifolia'', and tapioca from cassava (''Manihot esculenta''), which is oft ...
flour.
Some animal flesh forms a protein gel when cooked.
Eels and elvers, and
sipunculid
The Sipuncula or Sipunculida (common names sipunculid worms or peanut worms) is a class containing about 162 species of unsegmented marine annelid worms. The name ''Sipuncula'' is from the genus name '' Sipunculus'', and comes from the Latin ...
worms, are a delicacy in
Xiamen
Xiamen ( , ; ), also known as Amoy (, from Hokkien pronunciation ), is a sub-provincial city in southeastern Fujian, People's Republic of China, beside the Taiwan Strait. It is divided into six districts: Huli, Siming, Jimei, Tong'an ...
, China, as are
jellied eel
Jellied eels are a traditional English dish that originated in the 18th century, primarily in the East End of London. The dish consists of chopped eels boiled in a spiced stock that is allowed to cool and set, forming a jelly. It is usually s ...
s in the
East End of London, where they are eaten with mashed potatoes.
British cuisine has a rich tradition of
potted meat
Potted meat is a form of traditional food preservation in which hot cooked meat is placed in a pot, tightly packed to exclude air, and then covered with hot fat. As the fat cools, it hardens and forms an airtight seal, preventing some spoilage by ...
s. Meat off-cuts were, until the 1950s, preserved in
aspic
Aspic or meat jelly () is a savory gelatin made with a meat stock or broth, set in a mold to encase other ingredients. These often include pieces of meat, seafood, vegetable, or eggs. Aspic is also sometimes referred to as ''aspic gelée'' or ' ...
, a gel made from gelatin and clarified meat broth. Another form of preservation is setting the cooked food in a container and covering it with a layer of fat. Potted chicken liver can be prepared in this way, and so can
potted shrimps
Potted shrimps are a traditional British dish made with brown shrimp flavored with nutmeg. The dish consists of brown shrimp in nutmeg-flavoured butter, which has set in a small pot, the butter acting as a preservative. Cayenne pepper may also be ...
, to be served on toast.
Calf's foot jelly used to be prepared for invalids.
Jellying is one of the steps in producing traditional
pâté
''Pâté'' ( , , ) is a paste, pie or loaf filled with a forcemeat. Common forcemeats include ground meat from pork, poultry, fish or beef; fat, vegetables, herbs, spices and either wine or brandy (often cognac or armagnac). It is often ser ...
s. Many
jugged meats (see below) are also jellied.
Another type of jellying is
fruit preserves
Fruit preserves are preparations of fruits whose main preserving agent is sugar and sometimes acid, often stored in glass jars and used as a condiment or spread.
There are many varieties of fruit preserves globally, distinguished by the met ...
, which are preparations of cooked fruits, vegetables and sugar, often stored in glass jam jars and
Mason jar
A Mason jar, also known as a canning jar or fruit jar, is a glass jar used in home canning to preserve food. It was named after American tinsmith John Landis Mason, who patented it in 1858. The jar's mouth has a screw thread on its outer perime ...
s. Many varieties of fruit preserves are made globally, including sweet fruit preserves, such as those made from strawberry or apricot, and savory preserves, such as those made from tomatoes or squash. The ingredients used and how they are prepared determine the type of preserves;
jam
Jam is a type of fruit preserve.
Jam or Jammed may also refer to:
Other common meanings
* A firearm malfunction
* Block signals
** Radio jamming
** Radar jamming and deception
** Mobile phone jammer
** Echolocation jamming
Arts and ente ...
s,
jellies, and
marmalade
Marmalade is a fruit preserve made from the juice and peel of citrus fruits boiled with sugar and water. The well-known version is made from bitter orange. It is also made from lemons, limes, grapefruits, mandarins, sweet oranges, bergamot ...
s are all examples of different styles of fruit preserves that vary based upon the fruit used. In English, the word ''preserves'', in plural form, is used to describe all types of jams and jellies.
Jugging
Meat can be preserved by jugging. Jugging is the process of
stewing the meat (commonly
game or
fish
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...
) in a covered
earthenware jug or
casserole. The animal to be jugged is usually cut into pieces, placed into a tightly sealed jug with brine or
gravy
Gravy is a sauce often made from the juices of meats that run naturally during cooking and often thickened with wheat flour or corn starch for added texture. The gravy may be further coloured and flavoured with gravy salt (a simple mix of salt ...
, and stewed.
Red wine and/or the animal's own blood is sometimes added to the cooking liquid. Jugging was a popular method of preserving meat up until the middle of the 20th century.
Lye
Sodium hydroxide (
lye
A lye is a metal hydroxide traditionally obtained by leaching wood ashes, or a strong alkali which is highly soluble in water producing caustic basic solutions. "Lye" most commonly refers to sodium hydroxide (NaOH), but historically has been u ...
) makes food too
alkaline for bacterial growth. Lye will
saponify fats in the food, which will change its flavor and texture.
Lutefisk
''Lutefisk'' ( Norwegian, in Northern and parts of Central Norway, in Southern Norway; sv, lutfisk ; fi, lipeäkala ; literally " lye fish") is dried whitefish (normally cod, but ling and burbot are also used). It is made from aged sto ...
uses lye in its preparation, as do some olive recipes. Modern recipes for
century eggs also call for lye.
Pickling
Pickling is a method of preserving food in an edible, antimicrobial liquid. Pickling can be broadly classified into two categories: chemical pickling and fermentation pickling.
In chemical pickling, the food is placed in an edible liquid that inhibits or kills bacteria and other microorganisms. Typical pickling agents include
brine (high in salt),
vinegar
Vinegar is an aqueous solution of acetic acid and trace compounds that may include flavorings. Vinegar typically contains 5–8% acetic acid by volume. Usually, the acetic acid is produced by a double fermentation, converting simple sugars to eth ...
,
alcohol, and
vegetable oil
Vegetable oils, or vegetable fats, are oils extracted from seeds or from other parts of fruits. Like animal fats, vegetable fats are ''mixtures'' of triglycerides. Soybean oil, grape seed oil, and cocoa butter are examples of seed oils, or f ...
. Many chemical pickling processes also involve heating or boiling so that the food being preserved becomes saturated with the pickling agent. Common chemically pickled foods include
cucumbers
Cucumber (''Cucumis sativus'') is a widely-cultivated creeping vine plant in the Cucurbitaceae family that bears usually cylindrical fruits, which are used as culinary vegetables.[peppers
Pepper or peppers may refer to:
Food and spice
* Piperaceae or the pepper family, a large family of flowering plant
** Black pepper
* ''Capsicum'' or pepper, a genus of flowering plants in the nightshade family Solanaceae
** Bell pepper
** Chili ...]
,
corned beef,
herring, and
eggs
Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...
, as well as mixed vegetables such as
piccalilli
Piccalilli, or mustard pickle, is a British interpretation of South Asian pickles, a relish of chopped and pickled vegetables and spices.Spelling as per The Chambers Dictionary, 1994, . Regional recipes vary considerably.
Etymology
The ''Oxford ...
.
In fermentation pickling, bacteria in the liquid produce
organic acids as preservation agents, typically by a process that produces
lactic acid
Lactic acid is an organic acid. It has a molecular formula . It is white in the solid state and it is miscible with water. When in the dissolved state, it forms a colorless solution. Production includes both artificial synthesis as well as nat ...
through the presence of
lactobacillales
Lactobacillales are an order of gram-positive, low-GC, acid-tolerant, generally nonsporulating, nonrespiring, either rod-shaped (bacilli) or spherical (cocci) bacteria that share common metabolic and physiological characteristics. These bact ...
. Fermented pickles include
sauerkraut
Sauerkraut (; , "sour cabbage") is finely cut raw cabbage that has been fermented by various lactic acid bacteria. It has a long shelf life and a distinctive sour flavor, both of which result from the lactic acid formed when the bacteria ferm ...
,
nukazuke
is a type of Japanese preserved food, made by fermenting vegetables in rice bran (nuka), developed in the 17th century.
Almost any vegetable may be preserved using this technique, although some common varieties include eggplants, daikon, cabb ...
,
kimchi
''Kimchi'' (; ko, 김치, gimchi, ), is a traditional Korean side dish of salted and fermented vegetables, such as napa cabbage and Korean radish. A wide selection of seasonings are used, including '' gochugaru'' (Korean chili powder), ...
, and
surströmming
Surströmming (; ) is lightly salted fermented Baltic Sea herring traditional to Swedish cuisine since at least the 16th century. Surströmming or fermented herring should not be confused with the common dish fried herring or typically preserve ...
.
Sugaring
The earliest cultures have used
sugar as a preservative, and it was commonplace to store fruit in honey. Similar to pickled foods,
sugar cane
Sugarcane or sugar cane is a species of (often hybrid) tall, perennial grass (in the genus '' Saccharum'', tribe Andropogoneae) that is used for sugar production. The plants are 2–6 m (6–20 ft) tall with stout, jointed, fibrous stalk ...
was brought to Europe through the trade routes. In northern climates without sufficient sun to dry foods,
preserves
Fruit preserves are preparations of fruits whose main preserving agent is sugar and sometimes acid, often stored in glass jars and used as a condiment or spread.
There are many varieties of fruit preserves globally, distinguished by the meth ...
are made by heating the fruit with sugar.
[Nummer, B. (2002). "Historical Origins of Food Preservation" http://nchfp.uga.edu/publications/nchfp/factsheets/food_pres_hist.html. (Accessed on 5 May 2014)] "Sugar tends to draw water from the microbes (plasmolysis). This process leaves the microbial cells dehydrated, thus killing them. In this way, the food will remain safe from microbial spoilage."
Sugar is used to preserve fruits, either in an
antimicrobial
An antimicrobial is an agent that kills microorganisms or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals ar ...
syrup with fruit such as apples, pears, peaches, apricots, and plums, or in crystallized form where the preserved material is cooked in sugar to the point of crystallization and the resultant product is then stored dry. This method is used for the skins of
citrus
''Citrus'' is a genus of flowering trees and shrubs in the rue family, Rutaceae. Plants in the genus produce citrus fruits, including important crops such as oranges, lemons, grapefruits, pomelos, and limes. The genus ''Citrus'' is native to ...
fruit (candied peel),
angelica
''Angelica'' is a genus of about 60 species of tall biennial and perennial herbs in the family Apiaceae, native to temperate and subarctic regions of the Northern Hemisphere, reaching as far north as Iceland, Lapland, and Greenland. They gr ...
, and
ginger. Sugaring can be used in the production of
jam
Jam is a type of fruit preserve.
Jam or Jammed may also refer to:
Other common meanings
* A firearm malfunction
* Block signals
** Radio jamming
** Radar jamming and deception
** Mobile phone jammer
** Echolocation jamming
Arts and ente ...
and
jelly.
Modern industrial techniques
Techniques of food preservation were developed in research laboratories for commercial applications.
Pasteurization
Pasteurization is a process for preservation of liquid food. It was originally applied to combat the souring of young local wines. Today, the process is mainly applied to dairy products. In this method, milk is heated at about for 15–30 seconds to kill the bacteria present in it and cooling it quickly to to prevent the remaining bacteria from growing. The milk is then stored in sterilized bottles or pouches in cold places. This method was invented by
Louis Pasteur, a
French chemist, in 1862.
Vacuum packing
Vacuum-packing stores food in a vacuum environment, usually in an air-tight bag or bottle. The
vacuum
A vacuum is a space devoid of matter. The word is derived from the Latin adjective ''vacuus'' for "vacant" or " void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often di ...
environment strips bacteria of oxygen needed for survival. Vacuum-packing is commonly used for storing
nuts to reduce loss of flavor from oxidization. A major drawback to vacuum packaging, at the consumer level, is that vacuum sealing can deform contents and rob certain foods, such as cheese, of its flavor.
Freeze drying
Artificial food additives
Preservative
food additives
Food additives are substances added to food to preserve flavor or enhance taste, appearance, or other sensory qualities. Some additives have been used for centuries as part of an effort to preserve food, for example vinegar (pickling), salt (sal ...
can be ''
antimicrobial
An antimicrobial is an agent that kills microorganisms or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals ar ...
'' – which inhibit the growth of
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...
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 ...
, including
mold
A mold () or mould () is one of the structures certain fungi can form. The dust-like, colored appearance of molds is due to the formation of spores containing fungal secondary metabolites. The spores are the dispersal units of the fungi. Not ...
– or ''
antioxidant'', such as
oxygen absorbers, which inhibit the
oxidation
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...
of food constituents. Common antimicrobial preservatives include
calcium propionate
Calcium propanoate or calcium propionate has the formula Ca( C2 H5 C O O)2. It is the calcium salt of propanoic acid.
Uses
As a food additive, it is listed as E number 282 in the Codex Alimentarius. Calcium propionate is used as a preservative ...
,
sodium nitrate,
sodium nitrite
Sodium nitrite is an inorganic compound with the chemical formula NaNO2. It is a white to slightly yellowish crystalline powder that is very soluble in water and is hygroscopic. From an industrial perspective, it is the most important nitrite ...
,
sulfites (
sulfur dioxide,
sodium bisulfite
Sodium bisulfite (or sodium bisulphite, sodium hydrogen sulfite) is a chemical mixture with the approximate chemical formula NaHSO3. Sodium bisulfite in fact is not a real compound, but a mixture of salts that dissolve in water to give solutions ...
,
potassium hydrogen sulfite, etc.), and
EDTA
Ethylenediaminetetraacetic acid (EDTA) is an aminopolycarboxylic acid with the formula H2N(CH2CO2H)2sub>2. This white, water-soluble solid is widely used to bind to iron (Fe2+/Fe3+) and calcium ions (Ca2+), forming water-soluble complexes ev ...
.
Antioxidants include
butylated hydroxyanisole
Butylated hydroxyanisole (BHA) is a synthetic, waxy, solid petrochemical. Its antioxidant properties have caused it to be widely used as a preservative in food, food packaging, animal feed, cosmetics, pharmaceuticals, rubber, and petroleum produ ...
(BHA) and
butylated hydroxytoluene
Butylated hydroxytoluene (BHT), also known as dibutylhydroxytoluene, is a lipophilic organic compound, chemically a derivative of phenol, that is useful for its antioxidant properties. BHT is widely used to prevent free radical-mediated oxidat ...
(BHT). Other preservatives include
formaldehyde
Formaldehyde ( , ) (systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section ...
(usually in solution),
glutaraldehyde
Glutaraldehyde is an organic compound with the formula . The molecule consists of a five carbon chain doubly terminated with formyl (CHO) groups. It is usually used as a solution in water, and such solutions exists as a collection of hydrates, c ...
(insecticide),
ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...
, and
methylchloroisothiazolinone
Methylchloroisothiazolinone, also referred to as MCI, is the organic compound with the formula S(C2HCl)C(O)N(CH3). It is a white solid that melts near room temperature. The compound is an isothiazolinone, a class of heterocycles used as biocides. ...
. There is also another approach of impregnating packaging materials (plastic films or other) with antioxidants and antimicrobials, such as
butylated hydroxyanisole
Butylated hydroxyanisole (BHA) is a synthetic, waxy, solid petrochemical. Its antioxidant properties have caused it to be widely used as a preservative in food, food packaging, animal feed, cosmetics, pharmaceuticals, rubber, and petroleum produ ...
,
butylated hydroxytoluene
Butylated hydroxytoluene (BHT), also known as dibutylhydroxytoluene, is a lipophilic organic compound, chemically a derivative of phenol, that is useful for its antioxidant properties. BHT is widely used to prevent free radical-mediated oxidat ...
,
tocopherol
Tocopherols (; TCP) are a class of organic chemical compounds (more precisely, various methylated phenols), many of which have vitamin E activity. Because the vitamin activity was first identified in 1936 from a dietary fertility factor in rat ...
s,
hinokitiol
Hinokitiol (β-thujaplicin) is a natural monoterpenoid found in the wood of trees in the family Cupressaceae. It is a tropolone derivative and one of the thujaplicins. Hinokitiol is used in oral and skin care products, and is a food additive us ...
,
lysozyme
Lysozyme (EC 3.2.1.17, muramidase, ''N''-acetylmuramide glycanhydrolase; systematic name peptidoglycan ''N''-acetylmuramoylhydrolase) is an antimicrobial enzyme produced by animals that forms part of the innate immune system. It is a glycoside ...
,
nisin
Nisin is a polycyclic antibacterial peptide produced by the bacterium ''Lactococcus lactis'' that is used as a food preservative. It has 34 amino acid residues, including the uncommon amino acids lanthionine (Lan), methyllanthionine (MeLan), di ...
,
natamycin
Natamycin, also known as pimaricin, is an antifungal medication used to treat fungal infections around the eye. This includes infections of the eyelids, conjunctiva, and cornea. It is used as eyedrops. Natamycin is also used in the food indust ...
,
chitosan
Chitosan is a linear polysaccharide composed of randomly distributed β-(1→4)-linked D-glucosamine (deacetylated unit) and ''N''-acetyl-D-glucosamine (acetylated unit). It is made by treating the chitin shells of shrimp and other crustacean ...
, and
ε-polylysine.
Irradiation
Irradiation of food is the exposure of food to
ionizing radiation. Multiple types of ionizing radiation can be used, including
beta particles (high-energy
electron
The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family,
and are generally thought to be elementary particles because they have no ...
s) and
gamma ray
A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically ...
s (emitted from radioactive sources such as
cobalt-60
Cobalt-60 (60Co) is a synthetic radioactive isotope of cobalt with a half-life of 5.2713 years. It is produced artificially in nuclear reactors. Deliberate industrial production depends on neutron activation of bulk samples of the monoisot ...
or
cesium-137
Caesium-137 (), cesium-137 (US), or radiocaesium, is a radioactive isotope of caesium that is formed as one of the more common fission products by the nuclear fission of uranium-235 and other fissionable isotopes in nuclear reactors and nuclea ...
). Irradiation can kill bacteria, molds, and insect pests, reduce the ripening and spoiling of fruits, and at higher doses induce sterility. The technology may be compared to
pasteurization; it is sometimes called "cold pasteurization", as the product is not heated. Irradiation may allow lower-quality or contaminated foods to be rendered marketable.
National and international expert bodies have declared food irradiation as "wholesome"; organizations of the
United Nations
The United Nations (UN) is an intergovernmental organization whose stated purposes are to maintain international peace and security, develop friendly relations among nations, achieve international cooperation, and be a centre for harmoniz ...
, such as the
World Health Organization
The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of ...
and
Food and Agriculture Organization
The Food and Agriculture Organization of the United Nations (FAO)french: link=no, Organisation des Nations unies pour l'alimentation et l'agriculture; it, Organizzazione delle Nazioni Unite per l'Alimentazione e l'Agricoltura is an intern ...
, endorse food irradiation.
[World Health Organization. Wholesomeness of irradiated food. Geneva, Technical Report Series No. 659, 1981][World Health Organization. High-Dose Irradiation: Wholesomeness of Food Irradiated With Doses Above 10 kGy. Report of a Joint FAO/IAEA/WHO Study Group. Geneva, Switzerland: World Health Organization; 1999. WHO Technical Report Series No. 890] Consumers may have a negative view of irradiated food based on the misconception that such food is radioactive; in fact, irradiated food does not and cannot become radioactive. Activists have also opposed food irradiation for other reasons, for example, arguing that irradiation can be used to sterilize contaminated food without resolving the underlying cause of the contamination. International legislation on whether food may be irradiated or not varies worldwide from no regulation to a full ban.
Approximately 500,000 tons of food items are irradiated per year worldwide in over 40 countries. These are mainly
spice
A spice is a seed, fruit, root, bark, or other plant substance primarily used for flavoring or coloring food. Spices are distinguished from herbs, which are the leaves, flowers, or stems of plants used for flavoring or as a garnish. Spice ...
s and
condiment
A condiment is a preparation that is added to food, typically after cooking, to impart a specific flavor, to enhance the flavor, or to complement the dish. A table condiment or table sauce is more specifically a condiment that is served separat ...
s, with an increasing segment of fresh fruit irradiated for fruit fly quarantine.
Pulsed electric field electroporation
Pulsed electric field (PEF) electroporation is a method for processing cells by means of brief pulses of a strong electric field. PEF holds potential as a type of low-temperature alternative pasteurization process for sterilizing food products. In PEF processing, a substance is placed between two electrodes, then the pulsed electric field is applied. The electric field enlarges the pores of the cell membranes, which kills the cells and releases their contents. PEF for food processing is a developing technology still being researched. There have been limited industrial applications of PEF processing for the pasteurization of fruit juices. To date, several PEF treated juices are available on the market in Europe. Furthermore, for several years a juice pasteurization application in the US has used PEF. For cell disintegration purposes especially potato processors show great interest in PEF technology as an efficient alternative for their preheaters. Potato applications are already operational in the US and Canada. There are also commercial PEF potato applications in various countries in Europe, as well as in Australia, India, and China.
Modified atmosphere
Modifying atmosphere is a way to preserve food by operating on the atmosphere around it. Salad crops that are notoriously difficult to preserve are now being packaged in sealed bags with an atmosphere modified to reduce the oxygen () concentration and increase the
carbon dioxide
Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
() concentration. There is concern that, although salad vegetables retain their appearance and texture in such conditions, this method of preservation may not retain nutrients, especially
vitamin
A vitamin is an organic molecule (or a set of molecules closely related chemically, i.e. vitamers) that is an essential micronutrient that an organism needs in small quantities for the proper functioning of its metabolism. Essential nutrie ...
s.
There are two methods for preserving grains with carbon dioxide. One method is placing a block of
dry ice
Dry ice is the solid form of carbon dioxide. It is commonly used for temporary refrigeration as CO2 does not have a liquid state at normal atmospheric pressure and sublimates directly from the solid state to the gas state. It is used primarily ...
in the bottom and filling the can with the grain. Another method is purging the container from the bottom by gaseous carbon dioxide from a cylinder or bulk supply vessel.
Carbon dioxide
Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
prevents insects and, depending on concentration,
mold
A mold () or mould () is one of the structures certain fungi can form. The dust-like, colored appearance of molds is due to the formation of spores containing fungal secondary metabolites. The spores are the dispersal units of the fungi. Not ...
and
oxidation
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...
from damaging the grain. Grain stored in this way can remain edible for approximately five years.
Nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
gas () at concentrations of 98% or higher is also used effectively to kill insects in the grain through
hypoxia. However, carbon dioxide has an advantage in this respect, as it kills organisms through
hypercarbia
Hypercapnia (from the Greek ''hyper'' = "above" or "too much" and ''kapnos'' = "smoke"), also known as hypercarbia and CO2 retention, is a condition of abnormally elevated carbon dioxide (CO2) levels in the blood. Carbon dioxide is a gaseous pr ...
and hypoxia (depending on concentration), but it requires concentrations of roughly over 35%. This makes carbon dioxide preferable for fumigation in situations where a
hermetic seal
A hermetic seal is any type of sealing that makes a given object airtight (preventing the passage of air, oxygen, or other gases). The term originally applied to airtight glass containers, but as technology advanced it applied to a larger categor ...
cannot be maintained.
Air-tight storage of grains (sometimes called hermetic storage) relies on the respiration of grain, insects, and fungi that can modify the enclosed atmosphere sufficiently to control insect pests. This is a method of great antiquity, as well as having modern equivalents. The success of the method relies on having the correct mix of sealing, grain moisture, and temperature.
A patented process uses
fuel cells to exhaust and automatically maintain the exhaustion of
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...
in a shipping container, containing, for example, fresh fish.
Nonthermal plasma
This process subjects the surface of food to a "flame" of ionized gas molecules, such as helium or nitrogen. This causes micro-organisms to die off on the surface.
High-pressure food preservation
High-pressure food preservation or pascalization refers to the use of a food preservation technique that makes use of
high pressure
In science and engineering the study of high pressure examines its effects on materials and the design and construction of devices, such as a diamond anvil cell, which can create high pressure. By ''high pressure'' is usually meant pressures of th ...
. "Pressed inside a vessel exerting or more, food can be processed so that it retains its fresh appearance, flavor, texture and nutrients while disabling harmful microorganisms and slowing spoilage." By 2005, the process was being used for products ranging from
orange juice
Orange juice is a liquid extract of the orange tree fruit, produced by squeezing or reaming oranges. It comes in several different varieties, including blood orange, navel oranges, valencia orange, clementine, and tangerine. As well as vari ...
to
guacamole
Guacamole (; (informally shortened to ''guac'' in the United States since the 1980s) is an avocado-based dip, spread, or salad first developed in Mexico. In addition to its use in modern Mexican cuisine, it has become part of international cuisi ...
to
deli meat
Lunch meats—also known as cold cuts, luncheon meats, cooked meats, sliced meats, cold meats, sandwich meats, and deli meats—are precooked or cured meats that are sliced and served cold or hot. They are typically served in sandwiches or on ...
s and widely sold.
Biopreservation
Biopreservation is the use of natural or controlled
microbiota or
antimicrobial
An antimicrobial is an agent that kills microorganisms or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals ar ...
s as a way of preserving food and extending its
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 ...
.
Beneficial bacteria or the
fermentation products produced by these bacteria are used in biopreservation to control spoilage and render
pathogen
In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") 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 ...
s inactive in food.
[Yousef AE and Carolyn Carlstrom C (2003]
''Food microbiology: a laboratory manual''
Wiley, Page 226. . It is a benign ecological approach which is gaining increasing attention.
[Ananou S, Maqueda M, Martínez-Bueno M and Valdivia E (2007]
"Biopreservation, an ecological approach to improve the safety and shelf-life of foods"
In: A. Méndez-Vilas (Ed.) ''Communicating Current Research and Educational Topics and Trends in Applied Microbiology'', Formatex. .
Lactic acid bacteria
Lactobacillales are an order of gram-positive, low-GC, acid-tolerant, generally nonsporulating, nonrespiring, either rod-shaped ( bacilli) or spherical ( cocci) bacteria that share common metabolic and physiological characteristics. These bact ...
(LAB) have antagonistic properties that make them particularly useful as biopreservatives. When LABs compete for nutrients, their
metabolites often include active antimicrobials such as lactic acid, acetic acid, hydrogen peroxide, and
peptide
Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides.
...
bacteriocin
Bacteriocins are proteinaceous or peptidic toxins produced by bacteria to inhibit the growth of similar or closely related bacterial strain(s). They are similar to yeast and paramecium killing factors, and are structurally, functionally, and ec ...
s. Some LABs produce the antimicrobial
nisin
Nisin is a polycyclic antibacterial peptide produced by the bacterium ''Lactococcus lactis'' that is used as a food preservative. It has 34 amino acid residues, including the uncommon amino acids lanthionine (Lan), methyllanthionine (MeLan), di ...
, which is a particularly effective preservative.
[FAO]
Preservation techniques
Fisheries and aquaculture department, Rome. Updated 27 May 2005. Retrieved 14 March 2011.
LAB bacteriocins are used in the present day as an integral part of
hurdle technology Hurdle technology is a method of ensuring that pathogens in food products can be eliminated or controlled. This means the food products will be safe for consumption, and their shelf life will be extended. Hurdle technology usually works by combining ...
. Using them in combination with other preservative techniques can effectively control spoilage bacteria and other pathogens, and can inhibit the activities of a wide spectrum of organisms, including inherently resistant
Gram-negative bacteria
Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall ...
.
Hurdle technology
Hurdle technology Hurdle technology is a method of ensuring that pathogens in food products can be eliminated or controlled. This means the food products will be safe for consumption, and their shelf life will be extended. Hurdle technology usually works by combining ...
is a method of ensuring that
pathogen
In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") 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 ...
s in
food product
Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is ing ...
s can be eliminated or controlled by combining more than one approach. These approaches can be thought of as "hurdles" the pathogen has to overcome if it is to remain active in the food. The right combination of hurdles can ensure all pathogens are eliminated or rendered harmless in the final product.
Hurdle technology has been defined by Leistner (2000) as an intelligent combination of hurdles that secures the
microbial safety and stability as well as the
organoleptic
Organoleptic properties are the aspects of food, water or other substances that create an individual experience via the senses—including taste, sight, smell, and touch.
USDA uses
In traditional U.S. Department of Agriculture meat and poul ...
and nutritional quality and the economic viability of
food product
Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is ing ...
s.
[Leistner I (2000]
"Basic aspects of food preservation by hurdle technology"
''International Journal of Food Microbiology'', 55:181–186. The organoleptic quality of the food refers to its sensory properties, that is its look, taste, smell, and texture.
Examples of hurdles in a food system are high temperature during processing, low temperature during storage, increasing the
acidity
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 ...
, lowering the
water activity
Water activity (''aw'') is the partial vapor pressure of water in a solution divided by the standard state partial vapor pressure of water. In the field of food science, the standard state is most often defined as pure water at the same tempe ...
or
redox potential
Redox potential (also known as oxidation / reduction potential, ''ORP'', ''pe'', ''E_'', or E_) is a measure of the tendency of a chemical species to acquire electrons from or lose electrons to an electrode and thereby be reduced or oxidised respe ...
, and the presence of
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 or
biopreservatives. According to the type of pathogens and how risky they are, the intensity of the hurdles can be adjusted individually to meet consumer preferences in an economical way, without sacrificing the safety of the product.
[Alasalvar C (2010]
''Seafood Quality, Safety and Health Applications''
John Wiley and Sons, Page 203. .
See also
*
Blast chilling
*
Food engineering
*
Food microbiology
*
Food packaging
Food packaging is a packaging system specifically designed for food and represents one of the most important aspects among the processes involved in the food industry, as it provides protection from chemical, biological and physical alteratio ...
*
Food rheology
Food rheology is the study of the rheological properties of food, that is, the consistency and flow of food under tightly specified conditions.
The consistency, degree of fluidity, and other mechanical properties are important in understandi ...
*
Food science
Food science is the basic science and applied science of food; its scope starts at overlap with agricultural science and nutritional science and leads through the scientific aspects of food safety and food processing, informing the development ...
*
Food spoilage
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 s ...
*
Freeze-drying
*
Fresherized
*
List of dried foods
This is a list of dried foods. Food drying is a method of food preservation that works by removing water from the food, which inhibits the growth of bacteria and has been practiced worldwide since ancient times to preserve food. Where or when d ...
*
List of pickled foods
This is a list of pickled foods. Many various types of foods are pickled to preserve them and add flavor. Some of these foods also qualify as fermented foods.
Pickled foods
A
*
*
*
*
*
*
*
*
*
*
B
*
*
*
*
*
*
*
*
* ...
*
List of smoked foods
*
Refrigerate after opening
*
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 ...
Notes
Sources
References
*
*
*
Further reading
*
External links
A c. 1894 Gustav Hammer & Co. commercial cooking machinery catalogue.Preserving foods ~ from the Clemson Extension Home and Garden Information CenterNational Center for Home Food Preservation*
BBC News Online
BBC News Online is the website of BBC News, the division of the BBC responsible for newsgathering and production. It is one of the most popular news websites, with 1.2 billion website visits in April 2021, as well as being used by 60% of the U ...
US army food... just add urineHome Economics Archive: Tradition, Research, History (HEARTH)An e-book collection of over 1,000 classic books on home economics spanning 1850 to 1950, created by Cornell University'
Mann Library
*
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