|මෙම පිටුව හෝ ඡේදය වෙතින් Food storage container වෙතට ඒකාබද්ධ කිරීමට යෝජිතය. (සංංවාදය)|
ආහාර පරිරක්ෂණය යනු ආහාර නරක් වීමට (ගුණය, කීමට, යෝග්ය බව හෝ පෝෂණ අගය අඩු කරන) හේතු කාරක වන ක්ෂුද්ර ජීවීන්ගේ වේගය අතිශයින් අඩු කරන ක්රමයකි. නමුත් ආහාර පරිරක්ෂණය සහ ඒවාට විශේෂිත වූ ගුණාංග එකතු කිරීම සඳහා විෂ රහිත බැක්ටීරියා, යීස්ට් හෝ දිලීර භාවිත කරන ඇතැම් අවස්ථාද ඇත. යමක් අහාරයක් ලෙස පරිරක්ෂණය කිරීමේදී එහි පෝෂ්යදායී වටිනාකම, මතුපිට පෙනුම සහ රසය ඇති කිරීම සහ පවත්වා ගැනීම වැදගත්වේ. මෙය සංස්කෘතිය මත රඳා පවතී. එක් සංස්කෘතියක ජනයාට සුදුසු වන ආහාරයක් තවත් සංස්කෘතියකට නුසුදුසු විය හැකිය.
සාමාන්යයන් ආහාර පරිරක්ෂණය යොදා ගන්නේ මුඩු බවට හේතු වන ලිපිඩ ඔක්සිකරණය ප්රමාද කිරීමට මෙන්ම බැක්ටීරියා, දිලීර සහ අනෙකුත් ක්ෂුද්ර ජීවින්ගේ වැඩීම නවතලීමටයි. එමෙන්ම ඇපල් ගෙඩියක් කැපූ පසු සිදුවන එන්සයිමීය ප්රතික්රියා වැනි ක්රියාවලදී සිදුවන වර්ණ වෙනස්වීම් සහ ස්වභාවික නරක් වීම් නිශේධනය කරන ක්රියාවලියක්ද මෙයට ඇතුලත් වේ. ඇතැම් පරිරක්ෂණ ක්රම වලදී ප්රතිකාරයෙන් පසු ක්ෂුද්ර ජීවීන් නිසා නැවත නරක් වීම වැළක්වීම සඳහා ආහාරය සීල් කිරීම අවශ්ය වේ. වියලීම, දිගු කාලීනව විශේෂයක් නොමැතිව ආහාරය අසුරා තැබීම අනෙකුත් ක්රමෝපායන් වේ.
මෙම ක්රියාවලි සඳහා අදාළ වන පොදුවේ භාවිත වන ක්රම අතරට වියලීම, විසිරි වියලීම, හිමායන වියලීම, හිමායනය, රික්තක ඇසිරීම, ටින් කිරීම, පැණිවල දැමීම, සීනි ස්ඵටිකීකරණය, ආහාර ප්රකිරණය සහ පරිරක්ෂක ද්රව්ය හෝ කාබන් ඩයොක්සයිඩ් වැනි නිෂ්ක්රීය වායු එකතු කිරීම වැනි ක්රම ඇතුලත් වේ. අච්චාරු දැමීම, ලුණු දැමීම, දුම් ගැසීම, පැණිවල හෝ මද්යසාර වල දැමීම, සීනි ස්ඵටිකීකරණය සහ පදම් කිරීම වැනි අනෙකුත් ක්රම ආහාර පරිරක්ෂණය සඳහාම පමණක් නොව රස එකතු කිරීම සඳහා ද උපකාර වේ.
|ක්රමය||Effect on microbial growth or survival|
|Refrigeration||Low temperature to retard growth|
|Freezing||Low temperature and reduction of water activity prevents microbial growth, slowing of oxidation reactions|
|Drying, curing and conserving||Reduction in water activity sufficient to delay or prevent microbial growth|
|Vacuum and oxygen free modified atmosphere packaging||Low oxygen tension inhibits strict aerobes and delays growth of facultative anaerobes|
|Carbon dioxide enriched and or modified atmosphere packaging||Specific inhibition of some micro-organisms|
|Addition of weak acids; e.g. sodium lactate||Reduction of the intracellular pH of micro-organisms|
|Lactic fermentation||Reduction of pH value in situ by microbial action and sometimes additional inhibition by the lactic and acetic acids formed and by other microbial products. (e.g. ethanol, bacteriocins)|
|සීනි preservation||Cooking in high sucrose concentration creating too high osmotic pressure for most microbial survival.|
|Ethanol preservation||Steeping or cooking in Ethanol produces toxic inhibition of microbes. Can be combined with sugar preservation|
|Emulsification||Compartmentalisation and nutrient limitation within the aqueous droplets in water-in-oil emulsion foods|
|Addition of preservatives such as nitrite or sulphite ions||Inhibition of specific groups of micro-organisms|
|Pasteurization and appertization||Delivery of heat sufficient to inactivate target micro-organisms to the desired extent|
|Food irradiation (Radurization, radicidation and radappertization)||Delivery of ionising radiation to disrupt cellular RNA|
|Application of high hydrostatic pressure (Pascalization)||Pressure-inactivation of vegetative bacteria, yeasts and moulds|
|Pulsed electric field processing (PEF treatment9)||Short bursts of electricity for microbial inactivation|
පරිරක්ෂණ ක්රියාවලියේ අන්තර්ගතය:
- තාපය මගින් ක්ෂුද්ර ජීවීන් විනාශ කිරීම හෝ ස්වභාවික ලක්ෂණ වෙනස් කිරීම (උදා: නැටවීම)
- ඔක්සිකරණය (උදා: සල්ෆර් ඩයොක්සිඩ් භාවිතය)
- ධූලක නිශේධනය (උදා: දුම් ගැසීම, කාබන් ඩයොක්සයිඩ් භාවිතය, විනාකිරි, මද්යසාර යනාදිය)
- විජලනය (උදා: වියලීම)
- ආස්රැති නිශේධනය (උදා: පැණි වර්ග භාවිතය)
- අඩු උෂ්ණත්ව අක්රිය කිරීම (උදා: හිමායනය)
- අධි ජල පීඩනය (උදා: නව, 'ශීත' පැස්ටරීකරණ ක්රමයකි, ජල පීඩනය මගින් ආහාර වල ගුණ හානි කිරීමට හේතුවන සහ ආහාරවල සුරක්ෂිතතාවය සඳහා බලපාන ස්වභාවිකව හටගන්නා රෝගකාරක විනාශ කරයි)
- මෙම ක්රමවල නොයෙක් සංයෝජන
වියලීම යනු, බැක්ටීරියා වර්ධනය වැලැක්වීම හෝ ප්රමාද කිරීම සඳහා, ජලයේ ක්රියාකාරිත්වය අවශ්ය ප්රමාණයට අඩු කිරීමට යොදා ගන්නා පැරණි ආහාර පරිරක්ෂණ ක්රම අතරින් එකකි. එමෙන්ම වියලීම මගින් අහාරයේ බරද අඩු කරගත හැකිය. .යටි ලකුණු පෙළයටි ලකුණු පෙළ
හිමායනය, පිළියෙළ කිරීමට පෙර හිමයනයක් අවශ්ය නොවන ප්රකෘත අහාරද ඇතුළුව අහාර වර්ග විශාල ප්රමාණයක් පරිරක්ෂණය කිරීම සඳහා සාමාන්යයෙන් යොදා ගන්නා වානිජමය සහ ගෘහස්ථමය ක්රියාවලියකි. උදාහරණයක් වශයෙන්, අර්තාපල් ශීතකරණයේ තබයි. නමුත් අර්තාපල් මාස ගණනාවක් තුල සුරක්ෂිතව ගබඩා කර තැබීම සඳහා අවශ්ය වන්නේ සිසිල් අඳුරු ස්ථානයක් පමණි. බොහෝ රටවල ජාතික ආපදා සඳහා උපක්රමශීලී අහාර තොග විශාල ප්රමාණයක් දිගු කාලීනව ගබඩා කර තැබීම පිණිස සිසිල් ගබඩා යොදා ගනී.
Vacuum-packing stores food in a vacuum environment, usually in an air-tight bag or bottle. The vacuum environment strips bacteria of oxygen needed for survival, slowing spoiling. Vacuum-packing is commonly used for storing nuts to reduce loss of flavour from oxidation.
Salting or curing draws moisture from the meat through a process of osmosis. Meat is cured with salt or sugar, or a combination of the two. Nitrates and nitrites are also often used to cure meat and contribute the characteristic pink color, as well as inhibition of Clostridium botulinum.
Sugar is used to preserve fruits, either in syrup with fruit such as apples, pears, peaches, apricots, plums or in crystallized form where the preserved material is cooked in sugar to the point of crystallisation and the resultant product is then stored dry. This method is used for the skins of citrus fruit (candied peel), angelica and ginger. A modification of this process produces glacé fruit such as glacé cherries where the fruit is preserved in sugar but is then extracted from the syrup and sold, the preservation being maintained by the sugar content of the fruit and the superficial coating of syrup. The use of sugar is often combined with alcohol for preservation of luxury products such as fruit in brandy or other spirits. These should not be confused with fruit flavored spirits such as cherry brandy or Sloe gin.
Pickling is a method of preserving food in an edible anti-microbial liquid. Pickling can be broadly categorized as chemical pickling for example, In chemical pickling, the food is placed in an edible liquid that inhibits or kills bacteria and other micro-organisms. Typical pickling agents include brine (high in salt), vinegar, alcohol, and vegetable oil, especially olive oil but also many other oils. 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, peppers, corned beef, herring, and eggs, as well mixed vegetables such as piccalilli.
In fermentation pickling, the food itself produces the preservation agent, typically by a process that produces lactic acid. Fermented pickles include sauerkraut, nukazuke, kimchi, surströmming, and curtido. Some pickled cucumbers are also fermented.
Sodium hydroxide (lye) makes food too alkaline for bacterial growth. Lye will saponify fats in the food, which will change its flavor and texture. Lutefisk uses lye in its preparation, as do some olive recipes. Modern recipes for century eggs also call for lye. Masa harina and hominy use agricultural lime in their preparation and this is often misheard as 'lye'.
ටින් කිරීම සහ බෝතල් කීරීම[සංස්කරණය]
- See also Home canning
Canning involves cooking food, sealing it in sterile cans or jars, and boiling the containers to kill or weaken any remaining bacteria as a form of sterilization. It was invented by Nicolas Appert . Foods have varying degrees of natural protection against spoilage and may require that the final step occur in a pressure cooker. High-acid fruits like strawberries require no preservatives to can and only a short boiling cycle, whereas marginal fruits such as tomatoes 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 allowing contamination of canned food by the obligate anaerobe Clostridium botulinum, 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, though. Cooked mushrooms, 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.
Food may be preserved by cooking in a material that solidifies to form a gel. Such materials include gelatine, agar, maize flour and arrowroot flour. Some foods naturally form a protein gel when cooked such as eels and elvers, and sipunculid worms which are a delicacy in the town of Xiamen in Fujian province of the People's Republic of China. Jellied eels are a delicacy in the East End of ලන්ඩනය where they are eaten with mashed potatoes. Potted meats in aspic, (a gel made from gelatine 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.
Fruit preserved by jellying is known as jelly, marmalade, or fruit preserves. In this case, the jellying agent is usually pectin, either added during cooking or arising naturally from the fruit. Most preserved fruit is also sugared in jars. Heating, packaging and acid and sugar provide the preservation.
Meat can be preserved by jugging, the process of stewing the meat (commonly game or fish) 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, 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.
Irradiation of food is the exposure of food to ionizing radiation; either high-energy electrons or X-rays from accelerators, or by gamma rays (emitted from radioactive sources as Cobalt-60 or Caesium-137). The treatment has a range of effects, including 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 pasteurization; it is sometimes called 'cold pasteurization', as the product is not heated. Irradiation is not effective against viruses or prions, it cannot eliminate toxins already formed by microorganisms, and is only useful for food of high initial quality.
The radiation process is unrelated to nuclear energy, but it may use the radiation emitted from radioactive nuclides produced in nuclear reactors. Ionizing radiation 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 ensure that neither the workers in such facility nor the environment receive any radiation dose from the facility. Irradiated food does not become radioactive, and national and international expert bodies have declared food irradiation as wholesome. However, the wholesomeness of consuming such food is disputed by opponents and consumer organizations. National and international expert bodies have declared food irradiation as 'wholesome'; UN-organizations as WHO and FAO are endorsing to use food irradiation. International legislation on whether food may be irradiated or not varies worldwide from no regulation to full banning. Irradiation may allow lower quality or contaminated foodstuffs to be rendered marketable.
It is estimated that about 500,000 tons of food items are irradiated per year worldwide in over 40 countries. These are mainly spices and condiments with an increasing segment of fresh fruit irradiated for fruit fly quarantine.
Pulsed Electric Field Processing[සංස්කරණය]
Pulsed electric field (PEF) processing 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.
Modifiying atmosphere is a way to preserve food by operating on the atmosphere around it. Salad crops which are notoriously difficult to preserve are now being packaged in sealed bags with an atmosphere modified to reduce the oxygen (O2) concentration and increase the carbon dioxide (CO2) 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 vitamins. - - Grains may be preserved using carbon dioxide. A block of dry ice is placed in the bottom and the can is filled with grain. The can is then "burped" of excess gas. The carbon dioxide from the sublimation of the dry ice prevents insects, mold, and oxidation from damaging the grain. Grain stored in this way can remain edible for five years. - Nitrogen gas (N2) at concentrations of 98% or higher is also used effectively to kill insects in grain through hypoxia. However, carbon dioxide has an advantage in this respect as it kills organisms through both hypoxia and hypercarbia, requiring concentrations of only 80%, or so. This makes carbon dioxide preferable for fumigation in situations where a hermetic seal cannot be maintained.
Burial in the ground[සංස්කරණය]
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.
Many root vegetables are very resistant to spoilage and require no other preservation other than storage in cool dark conditions, for example by burial in the ground, such as in a storage clamp.
Century eggs are 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.
Most foods can be preserved in soil that is very dry and salty (thus a desiccant), or soil that is frozen.
Cabbage was traditionally buried in the fall in northern farms in the USA for preservation. Some methods keep it crispy while other methods produce sauerkraut[තහවුරු කරන්න]. A similar process is used in the traditional production of kimchi.
Sometimes meat is buried under conditions which 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.
Controlled use of micro-organism[සංස්කරණය]
Some foods, such as many cheeses, wines, and beers will keep for a long time because their production uses 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. Starter micro-organisms, salt, hops, controlled (usually cool) temperatures, controlled (usually low) levels of oxygen and/or other methods are used to create the specific controlled conditions that will support the desirable organisms that produce food fit for human consumption.
High pressure food preservation[සංස්කරණය]
High pressure food preservation refers to high pressure used for food preservation. "Pressed inside a vessel exerting 70,000 pounds per square inch or more, food can be processed so that it retains its fresh appearance, flavour, texture and nutrients while disabling harmful microorganisms and slowing spoilage." By 2001, adequate commercial equipment was developed so that by 2005 the process was being used for products ranging from orange juice to guacamole to deli meats and widely sold.
- Dietary supplement
- Food fortification
- Food rheology
- Food storage
- Food supplements
- Nutrification (aka food enrichment or fortification)
- Food Science
- Food Engineering
- Food technology
- Food and Bioprocess Technology
- Food safety
- Food microbiology
- Food chemistry
- Food packaging
- Food manufacturing
- Food engineering
- Refrigerate after opening
- Food processing
- Shelf life
- Gourmet Library and museum
- Nicolas Appert inventeur et humaniste by Jean-Paul Barbier, Paris, 1994 and http://www.appert-aina.com
- anon., Food Irradation - A technique for preserving and improving the safety of food, WHO, Geneva, 1991
- Hauther,W. & Worth, M., Zapped! Irradiation and the Death of Food, Food & Water Watch Press, Washington, DC, 2008
- Consumers International - Home
- NUCLEUS - Food Irradiation Clearances
- Food irradiation - Position of ADA J Am Diet Assoc. 2000;100:246-253
- 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
- "High-Pressure Processing Keeps Food Safe". Military.com. Retrieved 2008-12-16.
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.
|Food preservation හා සබැඳි මාධ්ය විකිමාධ්ය කොමන්ස් හි ඇත.|
- Dehydrating Food
- Preserving foods ~ from the Clemson Extension Home and Garden Information Center
- National Center for Home Food Preservation
- BBC News Online - US army food... just add urine
- Home 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's Mann Library.
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