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| '''Food preservation''' is to prevent the growth of ]s (such as ]s), or other microorganisms (although some methods work by introducing benign ] or fungi to the food), as well as slowing the ] of ]s that cause ]. Food preservation may also include processes that inhibit visual deterioration, such as the ] reaction in apples after they are cut during food preparation. | |||
| 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). Some traditional methods of preserving food have been shown to have a lower ] and ], when compared to modern methods.<ref></ref> | |||
| Some methods of food preservation are known to create ]s. In 2015, the ] of the ] classified processed meat, i.e. meat that has undergone salting, curing, fermenting, and smoking, as "] to humans".<ref>{{cite web |url= http://www.cancer.org/cancer/news/news/world-health-organization-says-processed-meat-causes-cancer|title=World Health Organization Says Processed Meat Causes Cancer|author= Stacy Simon |work=Cancer.org |date= October 26, 2015 }}</ref><ref>{{cite news |url=http://www.bbc.co.uk/news/health-34615621 |title = Processed meats do cause cancer - WHO|author= James Gallagher|work= BBC |date=26 October 2015 }}</ref><ref>{{cite web |url=https://www.iarc.fr/en/media-centre/pr/2015/pdfs/pr240_E.pdf| title=IARC Monographs evaluate consumption of red meat and processed meat |work= International Agency for Research on Cancer |date= 26 October 2015}}</ref> | |||
| Maintaining or creating nutritional value, ] and ] is an important aspect of food preservation. | |||
| == Traditional techniques == | |||
| New techniques of food preservation became available to the home chef from the dawn of ] until the ]. | |||
| === Curing === | |||
| ]" or "pink salt". It is typically a combination of salt and sodium nitrite, with the pink color added to distinguish it from ordinary salt.]] | |||
| {{Main|Curing (food preservation)}} | |||
| The earliest form of curing was dehydration or ], used as early as 12,000 BC. ] and ] 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 ]s ], ] and ].<ref name="Msagati, T. 2012">Msagati, T. (2012). "The Chemistry of Food Additives and Preservatives"</ref> Salt accelerates the drying process using ] and also inhibits the growth of several common strains of bacteria. More recently ]s have been used to cure meat, contributing a characteristic pink colour.<ref>{{cite web|last1=Nummer|first1=Brian|last2=Andress|first2=Elizabeth|title=Curing and Smoking Meats for Home Food Preservation|url=http://nchfp.uga.edu/publications/nchfp/lit_rev/cure_smoke_cure.html|publisher=National Center for Home Food Preservation|date=June 2015}}</ref> | |||
| === Cooling === | |||
| {{Main|Refrigeration}} | |||
| ] 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 ] 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 ]s and ]es. Rural people often did their own ], whereas town and city dwellers often relied on the ]. Today, root cellaring remains popular among people who value various goals, including ], ], traditional home ], ]ing, ], ], ], and others. | |||
| === Freezing === | |||
| {{Main|Frozen food}} | |||
| ] 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. | |||
| === Boiling === | |||
| {{Main|Boiling}} | |||
| Boiling liquid food items can kill any existing microbes. Milk and water are often boiled to kill any harmful microbes that may be present in them. | |||
| === Heating === | |||
| Heating to temperatures which are sufficient to kill microorganisms inside the food is a method used with ]s. Milk is also boiled before storing to kill many microorganisms. | |||
| === Sugaring === | |||
| {{see also |Sugaring}} | |||
| The earliest cultures have used ] as a ], and it was commonplace to store ] in ]. Similar to pickled foods, ] was brought to Europe through the trade routes. In northern climates without sufficient sun to dry foods, ] are made by heating the fruit with sugar.<ref name="nchfp.uga.edu">Nummer, B. (2002). "Historical Origins of Food Preservation" http://nchfp.uga.edu/publications/nchfp/factsheets/food_pres_hist.html. (Accessed on May 5, 2014)</ref> "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."<ref name="Msagati, T. 2012" /> Sugar is used to preserve fruits, either in an ] syrup with fruit such as ]s, ]s, ]es, ]s, and ]s, 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 ] fruit (candied peel), ], and ]. Also, sugaring can be used in the production of ] and ]. | |||
| === Pickling === | |||
| {{Main|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 ] (high in salt), ], ], and ]. 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 ], ], ], ], and ], as well as mixed vegetables such as ]. | |||
| In fermentation pickling, bacteria in the liquid produce ]s as preservation agents, typically by a process that produces ] through the presence of ]. Fermented pickles include ], ], ], and ]. | |||
| === Lye === | |||
| {{main|Sodium hydroxide#Food preparation}} | |||
| ] (]) makes food too ] for bacterial growth. Lye will ] fats in the food, which will change its flavor and texture. ] uses lye in its preparation, as do some olive recipes. Modern recipes for ]s also call for lye. | |||
| === Canning === | |||
| ] | |||
| {{Main|Canning}} | |||
| {{See also|Home canning}} | |||
| ] involves cooking food, sealing it in sterilized cans or jars, and ] the containers to kill or weaken any remaining bacteria as a form of ]. It was invented by the French confectioner ].<ref>''Nicolas Appert inventeur et humaniste'' by Jean-Paul Barbier, Paris, 1994 and http://www.appert-aina.com</ref> 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 wasn't understood until 1864 when Louis Pasteur found the relationship between microorganisms, food spoilage, and illness.<ref name="nchfp.uga.edu" /> | |||
| Foods have varying degrees of natural protection against spoilage and may require that the final step occur in a ]. High-acid fruits like ] require no preservatives to can and only a short boiling cycle, whereas marginal vegetables such as ]s 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 ] allowing contamination of canned food by the obligate ] '']'', 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 mushrooms, handled poorly and then canned, can support the growth of ], which produces a toxin that is not destroyed by canning or subsequent reheating. | |||
| For foods like avocados chef's often use what is called a short term canning approach where they immerse the avocado in water. This is only a short term canning like process that is recommended if using the avocado within a few hours. A longer term canning approach is to wrap it in saran wrap as this keeps the antioxidants from leaving the avocado long term, preserving its nutritional value. This technique is actually far superior than the immersion method but in the restaurant business appearance is a major factor and the saran wrap will cause the avocado to brown slightly. In the end the saran wrap is a more economically beneficial approach as the avocados last longer. | |||
| === Jellying === | |||
| {{Main|Aspic}}{{See also|Potted shrimps|Confit}} | |||
| Food may be preserved by cooking in a material that solidifies to form a gel. Such materials include ], ], ] flour, and ] flour. Some foods naturally form a ] gel when cooked, such as ], and ] worms, which are a delicacy in ], in the Fujian province of the ]. ]s are a delicacy in the East End of ], where they are eaten with mashed potatoes. Potted meats in ] (a gel made from gelatin and clarified meat broth) were a common way of serving meat off-cuts in the UK until the 1950s. Many jugged meats are also jellied. | |||
| A traditional British way of preserving meat (particularly ]) is by setting it in a pot and sealing it with a layer of fat. Also common is potted chicken liver; jellying is one of the steps in producing traditional ]s. | |||
| === Jugging === | |||
| {{Main|Jugging}} | |||
| Meat can be preserved by jugging. Jugging is the process of ] the meat (commonly ] or ]) in a covered ] jug or ]. The animal to be jugged is usually cut into pieces, placed into a tightly-sealed jug with brine or ], and stewed. ] 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. | |||
| === Burial === | |||
| Burial of food can preserve it due to a variety of factors: lack of light, lack of oxygen, cool temperatures, pH level, or ]s 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 ] 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 ]. ]s 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. ] was traditionally buried during ] in northern US farms for preservation. Some methods keep it crispy while other methods produce ].{{Citation needed|date=January 2008}} A similar process is used in the traditional production of ]. 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. Before burial, meat (pig/boar) can be fatted. The tallow of the animal is heated and poured over meat in a barrel. Once the fat hardens the barrel is sealed and buried in a cold cellar or ground. | |||
| In ], it is practical to store rice by burying it underground. This method helps to store for three to six months during the dry season. | |||
| === Fermentation === | |||
| {{See also|Fermentation (food)}} | |||
| Some foods, such as many ]s, ]s, and ]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.<ref name="nchfp.uga.edu" /> | |||
| == Modern industrial techniques == | |||
| Techniques of food preservation were developed in research laboratories for commercial applications. | |||
| === Pasteurization === | |||
| {{Main|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 {{cvt|70|C|F}} for 15–30 seconds to kill the bacteria present in it and cooling it quickly to {{cvt|10|C|F}} 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 ], a ] chemist, in 1862. | |||
| === Vacuum packing === | |||
| {{Main|Vacuum packing}} | |||
| Vacuum-packing stores food in a vacuum environment, usually in an air-tight bag or bottle. The ] environment strips bacteria of oxygen needed for survival. Vacuum-packing is commonly used for storing ] 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. | |||
| === Artificial food additives === | |||
| {{Main|Preservatives}} | |||
| Preservative food additives can be ''antimicrobial''—which inhibit the growth of ] or ], including ]—or '']'', such as ]s, which inhibit the ] of food constituents. Common antimicrobial preservatives include ], ], ], ]s (], ], ], etc.), and ]. ]s include ] (BHA) and ] (BHT). Other preservatives include ] (usually in solution), ] (insecticide), ], and ]. | |||
| === Irradiation === | |||
| {{Main|Food irradiation}} | |||
| Irradiation of food<ref>anon., Food Irradation – A technique for preserving and improving the safety of food, WHO, Geneva, 1991</ref> is the exposure of food to ]. The two types of ionizing radiation used are ]s (high-energy ]s) and ]s (emitted from radioactive sources such as ] or ]). Treatment effects include killing bacteria, molds, and insect pests, reducing the ripening and spoiling of fruits, and at higher doses inducing sterility. The technology may be compared to ]; it is sometimes called "cold pasteurization", as the product is not heated. | |||
| The irradiation process is not directly related to ], but does use radioactive isotopes produced in ]s. Cobalt-60, for example does not occur naturally and can only be produced through neutron bombardment of ]. Ionizing radiation at high energy levels is hazardous to life (hence its usefulness in sterilisation); for this reason, irradiation facilities have a heavily shielded irradiation room where the process takes place. Radiation safety procedures are used to ensure that neither the workers in such facilities nor the environment receives any radiation dose above administrative limits. Irradiated food does not and cannot become radioactive, and national and international expert bodies have declared food irradiation as wholesome.<ref name="JECFI">World Health Organization. Wholesomeness of irradiated food. Geneva, Technical Report Series No. 659, 1981</ref><ref name="JSGHDI">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</ref> However, the wholesomeness of consuming such food is disputed by opponents<ref>Hauther, W. & Worth, M., Zapped! Irradiation and the Death of Food, Food & Water Watch Press, Washington, DC, 2008</ref> and consumer organizations.<ref> {{webarchive |url=https://web.archive.org/web/20100818042937/http://www.consumersinternational.org/homepage.asp |date=18 August 2010 }}</ref> National and international expert bodies have declared food irradiation as "wholesome"; organizations of the ], such as the ] and ], endorse food irradiation. International legislation on whether food may be irradiated or not varies worldwide from no regulation to full banning.<ref> {{webarchive|url=https://web.archive.org/web/20080526025627/http://nucleus.iaea.org/NUCLEUS/nucleus/Content/Applications/FICdb/FoodIrradiationClearances.jsp?module=cif |date=26 May 2008 }}</ref> Irradiation may allow lower-quality or contaminated foods to be rendered marketable. | |||
| Approximately 500,000 tons of food items are irradiated per year worldwide in over 40 countries. These are mainly ]s and ]s with an increasing segment of fresh fruit irradiated for fruit fly quarantine.<ref> {{webarchive|url=https://web.archive.org/web/20160216174601/http://www.mindfully.org/Food/Irradiation-Position-ADA.htm |date=16 February 2016 }}</ref><ref>C.M. Deeley, M. Gao, R. Hunter, D.A.E. Ehlermann, The development of food irradiation in the Asia Pacific, the Americas and Europe; tutorial presented to the International Meeting on Radiation Processing, Kuala Lumpur, 2006. http://www.doubleia.org/index.php?sectionid=43&parentid=13&contentid=494</ref> | |||
| === Pulsed electric field electroporation === | |||
| {{Main|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.<ref>{{Cite web|url=http://www.elea-technology.com|title=Elea Pulsed Electric Field Technology - Homepage|last=|first=|date=|website=www.elea-technology.com|language=en|dead-url=|access-date=2017-03-02}}</ref> | |||
| === Modified atmosphere === | |||
| {{Main|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 (O<sub>2</sub>) concentration and increase the ] (CO<sub>2</sub>) 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 ]s. | |||
| There are two methods for preserving grains with carbon dioxide. One method is placing a block of ] 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. | |||
| ] prevents insects and, depending on concentration, ] and ] from damaging the grain. Grain stored in this way can remain edible for approximately five years.{{citation needed|date=December 2010}} | |||
| ] gas (N<sub>2</sub>) at concentrations of 98% or higher is also used effectively to kill insects in the grain through ].<ref>Annis, P.C. and Dowsett, H.A. 1993. Low oxygen disinfestation of grain: exposure periods needed for high mortality. Proc. International Conference on Controlled Atmosphere and Fumigation. Winnipeg, June 1992, Caspit Press, Jerusalem, pp 71-83.</ref> However, carbon dioxide has an advantage in this respect, as it kills organisms through ] and hypoxia (depending on concentration), but it requires concentrations of above 35%,<ref>Annis, P.C. and Morton, R. 1997. The acute mortality effects of carbon dioxide on various life stages of Sitophilus oryzae. J. Stored Prod.Res. 33. 115-124</ref> or so. This makes carbon dioxide preferable for fumigation in situations where a ] cannot be maintained. | |||
| Controlled Atmospheric Storage (CA): "CA storage is a non-chemical process. Oxygen levels in the sealed rooms are reduced, usually by the infusion of nitrogen gas, from the approximate 21 percent in the air we breathe to 1 percent or 2 percent. Temperatures are kept at a constant {{cvt|0–2|C|F}}. Humidity is maintained at 95 percent and carbon dioxide levels are also controlled. Exact conditions in the rooms are set according to the apple variety. Researchers develop specific regimens for each variety to achieve the best quality. Computers help keep conditions constant." | |||
| "Eastern Washington, where most of Washington’s apples are grown, has enough warehouse storage for 181 million boxes of fruit, according to a report done in 1997 by managers for the Washington State Department of Agriculture Plant Services Division. The storage capacity study shows that 67 percent of that space—enough for 121,008,000 boxes of apples—is CA storage." | |||
| <ref></ref> | |||
| 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,<ref>Various authors, Session 1: Natural Air-Tight Storage In: Shejbal, J., ed., Controlled Atmosphere Storage of Grains, Elsevier: Amsterdam, 1-33</ref> as well as having modern equivalents. The success of the method relies on having the correct mix of sealing, grain moisture, and temperature.<ref>Annis P.C. and Banks H.J. 1993. Is hermetic storage of grains feasible in modern agricultural systems? In "Pest control and sustainable agriculture" Eds S.A. Corey, D.J. Dall and W.M. Milne. CSIRO, Australia. 479-482</ref> | |||
| A patented process uses ]s to exhaust and automatically maintain the exhaustion of ] in a shipping container, containing, for example, fresh fish.<ref name=ADN51813>{{cite news|title=Laine Welch: Fuel cell technology boosts long-distance fish shipping |url=http://www.adn.com/2013/05/18/2907670/laine-welch-fuel-cell-technology.html |accessdate=May 19, 2013 |newspaper=Anchorage Daily News |date=May 18, 2013 |author=Laine Welch |deadurl=yes |archiveurl=https://web.archive.org/web/20130609190326/http://www.adn.com/2013/05/18/2907670/laine-welch-fuel-cell-technology.html |archivedate=9 June 2013 |df=dmy }}</ref> | |||
| === Nonthermal plasma === | |||
| {{Main|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.<ref>NWT magazine, December 2012</ref> | |||
| === High-pressure food preservation === | |||
| {{Main|Pascalization}} | |||
| High-pressure food preservation or pascalization refers to the use of a food preservation technique that makes use of ]. "Pressed inside a vessel exerting {{convert|70,000|psi|MPa}} 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 ] to ] to ]s and widely sold.<ref name=military>{{cite news |first= |last= |authorlink= |coauthors= |title=High-Pressure Processing Keeps Food Safe |url=http://www.military.com/soldiertech/0,14632,Soldiertech_Squeeze,,00.html |quote=Pressed inside a vessel exerting 70,000 pounds per square inch or more, food can be processed so that it retains its fresh appearance, flavor, texture and nutrients while disabling harmful microorganisms and slowing spoilage. |work=] |date= |accessdate=2008-12-16 |archiveurl = https://web.archive.org/web/20080202232043/http://www.military.com/soldiertech/0,14632,Soldiertech_Squeeze,,00.html |archivedate = 2008-02-02}}</ref> | |||
| === Biopreservation === | |||
| ]. Some ] manufacture nisin. It is a particularly effective preservative.]] | |||
| {{Main|Biopreservation}} | |||
| ] is the use of natural or controlled ] or ]s as a way of preserving food and extending its ].<ref name="Ananou1 et al" /> Beneficial bacteria or the ] products produced by these bacteria are used in biopreservation to control ] and render ]s inactive in food.<ref name="Yousef&Carlstrom">Yousef AE and Carolyn Carlstrom C (2003) Wiley, Page 226. {{ISBN|978-0-471-39105-0}}.</ref> It is a benign ecological approach which is gaining increasing attention.<ref name="Ananou1 et al">Ananou S, Maqueda M, Martínez-Bueno M and Valdivia E (2007) In: A. Méndez-Vilas (Ed.) ''Communicating Current Research and Educational Topics and Trends in Applied Microbiology'', Formatex. {{ISBN|978-84-611-9423-0}}.</ref> | |||
| Of special interest are ] (LAB). Lactic acid bacteria have antagonistic properties that make them particularly useful as biopreservatives. When LABs compete for nutrients, their ]s often include active antimicrobials such as lactic acid, acetic acid, hydrogen peroxide, and ] ]s. Some LABs produce the antimicrobial ], which is a particularly effective preservative.<ref name="FAO preservation">FAO: Fisheries and aquaculture department, Rome. Updated 27 May 2005. Retrieved 14 March 2011.</ref><ref>Alzamora SM, Tapia MS and López-Malo A (2000) Springer, Page 266. {{ISBN|978-0-8342-1672-3}}.</ref> | |||
| These days, LAB bacteriocins are used as an integral part of ]. 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 ].<ref name="Ananou1 et al" /> | |||
| === Hurdle technology === | |||
| {{Main|Hurdle technology}} | |||
| ] is a method of ensuring that ]s in ]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.<ref name="Alasalvar" /> | |||
| Hurdle technology has been defined by Leistner (2000) as an intelligent combination of hurdles that secures the ] safety and stability as well as the ] and nutritional quality and the economic viability of ]s.<ref>Leistner I (2000) ''International Journal of Food Microbiology'', '''55''':181–186.</ref> 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 ], lowering the ] or ], and the presence of ]s or ]s. 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.<ref name="Alasalvar">Alasalvar C (2010) John Wiley and Sons, Page 203. {{ISBN|978-1-4051-8070-2}}.</ref> | |||
| <center> | |||
| {| class="wikitable" | |||
| |- | |||
| ! colspan="3" style="text-align:center; width:560px;"| Principal hurdles used for food preservation (after Leistner, 1995)<ref>Leistner L (1995) In Gould GW (Ed.) ''New Methods of Food Preservation'', Springer, pp. 1-21. {{ISBN|978-0-8342-1341-8}}.</ref><ref name="Lee">Lee S (2004) ''Internet Journal of Food Safety'', '''4''': 21–32.</ref> | |||
| |- | |||
| ! Parameter | |||
| ! Symbol | |||
| ! Application | |||
| |- | |||
| | High temperature | |||
| | style="text-align:center;"| F | |||
| | Heating | |||
| |- | |||
| | Low temperature | |||
| | style="text-align:center;"| T | |||
| | ], ] | |||
| |- | |||
| | Reduced ] | |||
| | style="text-align:center;"| a<sub>w</sub> | |||
| | ], ], ] | |||
| |- | |||
| | Increased ] | |||
| | style="text-align:center;"| ] | |||
| | Acid addition or formation | |||
| |- | |||
| | Reduced ] | |||
| | style="text-align:center;"| E<sub>h </sub> | |||
| | Removal of oxygen or addition of ] | |||
| |- | |||
| | ]s | |||
| | | |||
| | Competitive ] such as ] ] | |||
| |- | |||
| | Other ]s | |||
| | | |||
| | ]s, ]s, ]s | |||
| |} | |||
| </center> | |||
| == See also == | |||
| {{Portal|Food}} | |||
| {{div col|colwidth=30em}} | |||
| * ] | |||
| * ] | |||
| * ] | |||
| * ] | |||
| * ] | |||
| * ] | |||
| * ] | |||
| * ] | |||
| * ] | |||
| * ] | |||
| * ] | |||
| * ] | |||
| * ] | |||
| * ] | |||
| {{div col end}} | |||
| == Notes == | |||
| {{Reflist|30em}} | |||
| == References == | |||
| {{Refbegin}} | |||
| * {{cite book | title = Food Conservation | first = Astri | last = Riddervold | isbn = 978-0-907325-40-6}} | |||
| * {{cite news | title = Thermal food processing optimization: algorithms and software | first = Nunes | last = Abakarov | journal = Food Engineering | url = http://tomakechoice.com/paper/OPTPROx.pdf}} | |||
| * {{cite news | title = Multi-criteria optimization and decision-making approach for improving of food engineering processes | first = Sushkov, Mascheroni | last = Abakarov | journal = International Journal of Food Studies | url = http://tomakechoice.com/paper/MCDM&OD_IJFS.pdf}} | |||
| {{Refend}} | |||
| ==Further reading== | |||
| * {{Cite book |last=Marx de Salcedo |first=Anastacia |authorlink= |year=2015 |title=Combat-ready Kitchen: How the U.S. military shapes the way you eat |url= |location=New York |publisher=Current/Penguin |isbn=9781101601648 }} | |||
| == External links == | |||
| {{Commons category|Food preservation}} | |||
| * | |||
| * | |||
| * | |||
| * ] – | |||
| * <br />An e-book collection of over 1,000 classic books on home economics spanning 1850 to 1950, created by Cornell University's . | |||
| {{Food preservation}} | |||
| {{Cooking techniques}} | |||
| {{Consumer Food Safety}} | |||
| {{Use dmy dates|date=March 2011}} | |||
| ] | |||
| ] | |||