Англійська мова

Vacuum packaging products using plastic bags, canisters, bottles, or mason jars are available for home use.

Vacuum packaging delicate food items can be done by using an inert gas kit, typically available on chamber vacuum sealers. After air has been removed, an inert gas (such as nitrogen) is added to maintain the preservation of packaged food while preventing damage. An example of inert gas for packaging delicate foods is potato chips.

External Sealers

External vacuum sealers involve a bag being attached to the vacuum-sealing machine externally. The machine will remove the air and seal the bag, which is all done outside the machine.

Chamber Sealers

Chamber sealers require the entire product to be placed within the machine. Like external sealers, a plastic bag is typically used for packaging. Once the product is placed in the machine, the lid is closed and air is removed. Once the air is removed, the bag is sealed and the atmosphere within the chamber is returned back to normal. The lid is then opened and the product removed. Chamber sealers are typically used for higher-volume packaging.

Manufacturers of chamber type vacuum packing machines include: Cryovac, Multivac, Sammic, VC999, Sevana and several others.

Preventing Freezer Burn

When foods are frozen without preparation, freezer burn can occur. It happens when the surface of the food is dehydrated, and this leads to a dried and leathery appearance. Freezer burn also ruins the flavor and texture of foods. Vacuum packing prevents freezer burn by preventing the food from exposure to the cold, dry air.

Sous-vide Cooking

Vacuum packaging also allows for a special cooking method, Sous-vide. Sous-vide, meaning "under vacuum" in French, involves poaching food that is vacuum sealed in a plastic bag.

Security

Due to an oxygen-poor environment, anaerobic microorganism can proliferate, so vacuum packing is often used in combination with other treatment.

Text 13. Freeze-drying

Freeze-drying (also known as lyophilisation, lyophilization or cryodesiccation) is a dehydration process typically used to preserve a perishable material or make the material more convenient for transport. Freeze-drying works by freezing the material and then reducing the surrounding pressure and adding enough heat to allow the frozen water in the material to sublime directly from the solid phase to the gas phase. The origins of freeze drying.

Freeze-drying was first actively developed during WWII. Serum being sent to Europe for medical treatment of the wounded required refrigeration. Due to the lack of available refrigeration, many serum supplies were spoiling before reaching the intended recipients. The freeze-drying process was developed as a commercial technique that enabled serum to be rendered chemically stable and viable without having to be refrigerated. Shortly thereafter, the freeze dry process was applied to penicillin and bone, and lyophilization became recognized as an important technique for preservation of biologicals. Since that time, freeze-drying has been used as a preservation or processing technique for a wide variety of products. Some of the applications include the processing of pharmaceuticals, diagnostic kits, restoration of water damaged documents, river bottom sludge prepared for hydrocarbon analysis, ceramics used in the semiconductor industry, viral or bacterial cultures, tissues prepared for analysis, the production of synthetic skins and restoration of historic/reclaimed boat hulls.

The freeze-drying process

There are four stages in the complete drying process: pretreatment, freezing, primary drying, and secondary drying.

Pretreatment

Pretreatment includes any method of treating the product prior to freezing. This may include concentrating the product, formulation revision (i.e., addition of components to increase stability and/or improve processing), decreasing a high vapor pressure solvent or increasing the surface area. In many instances the decision to pretreat a product is based on theoretical knowledge of freeze-drying and its requirements, or is demanded by cycle time or product quality considerations. Methods of pretreatment include: Freeze concentration, Solution phase concentration, Formulation to Preserve Product Appearance, Formulation to Stabilize Reactive Products, Formulation to Increase the Surface Area, and Decreasing High Vapor Pressure Solvents.

Freezing

In a lab, this is often done by placing the material in a freeze-drying flask and rotating the flask in a bath, called a shell freezer, which is cooled by mechanical refrigeration, dry ice and methanol, or liquid nitrogen. On a larger scale, freezing is usually done using a freeze-drying machine. In this step, it is important to cool the material below its triple point, the lowest temperature at which the solid and liquid phases of the material can coexist. This ensures that sublimation rather than melting will occur in the following steps. Larger crystals are easier to freeze-dry. To produce larger crystals, the product should be frozen slowly or can be cycled up and down in temperature. This cycling process is called annealing. However, in the case of food, or objects with formerly-living cells, large ice crystals will break the cell walls (a problem discovered, and solved, by Clarence Birdseye), resulting in the destruction of more cells, which can result in increasingly poor texture and nutritive content. In this case, the freezing is done rapidly, in order to lower the material to below its eutectic point quickly, thus avoiding the formation of ice crystals. Usually, the freezing temperatures are between -50 °C and -80 °C. The freezing phase is the most critical in the whole freeze-drying process, because the product can be spoiled if badly done.

Amorphous materials do not have a eutectic point, but they do have a critical point, below which the product must be maintained to prevent melt-back or collapse during primary and secondary drying.

Primary drying

During the primary drying phase, the pressure is lowered (to the range of a few millibars), and enough heat is supplied to the material for the water to sublimate. The amount of heat necessary can be calculated using the sublimating molecules' latent heat of sublimation. In this initial drying phase, about 95% of the water in the material is sublimated. This phase may be slow (can be several days in the industry), because, if too much heat is added, the material's structure could be altered.

In this phase, pressure is control led through the application of partial vacuum. The vacuum speeds sublimation, making it useful as a deliberate drying process. Furthermore, a cold condenser chamber and/or condenser plates provide a surface(s) for the water vapour to re-solidify on. This condenser plays no role in keeping the material frozen; rather, it prevents water vapor from reaching the vacuum pump, which could degrade the pump's performance. Condenser temperatures are typically below -50 °C (-60 °F).

It is important to note that, in this range of pressure, the heat is brought mainly by conduction or radiation; the convection effect is considered to be inefficient.

Secondary drying

The secondary drying phase aims to remove unfrozen water molecules, since the ice was removed in the primary drying phase. This part of the freeze-drying process is governed by the material's adsorption isotherms. In this phase, the temperature is raised higher than in the primary drying phase, and can even be above 0 °C, to break any physico-chemical interactions that have formed between the water molecules and the frozen material. Usually the pressure is also lowered in this stage to encourage desorption (typically in the range of microbars, or fractions of a pascal). However, there are products that benefit from increased pressure as well.

After the freeze-drying process is complete, the vacuum is usually broken with an inert gas, such as nitrogen, before the material is sealed.

At the end of the operation, the final residual water content in the product is extremely low, around 1% to 4%.

Properties of freeze-dried products

If a freeze-dried substance is sealed to prevent the reabsorption of moisture, the substance may be stored at room temperature without refrigeration, and be protected against spoilage for many years. Preservation is possible because the greatly reduced water content inhibits the action of microorganisms and enzymes that would normally spoil or degrade the substance.

Freeze-drying also causes less damage to the substance than other dehydration methods using higher temperatures. Freeze-drying does not usually cause shrinkage or toughening of the material being dried. In addition, flavours, smells and nutritional content generally remain unchanged, making the process popular for preserving food. However, water is not the only chemical capable of sublimation, and the loss of other volatile compounds such as acetic acid (vinegar) and alcohols can yield undesirable results.

Freeze-dried products can be rehydrated (reconstituted) much more quickly and easily because the process leaves microscopic pores. The pores are created by the ice crystals that sublimate, leaving gaps or pores in their place. This is especially important when it comes to pharmaceutical uses. Freeze-drying can also be used to increase the shelf life of some pharmaceuticals for many years.

Freeze-drying protectants

Similar to cryoprotectants, some molecules protect freeze-dried material. Known as lyoprotectants, these molecules are typically polyhydroxy compounds such as sugars (mono-, di-, and polysaccharides), polyalcohols, and their derivatives. Trehalose and sucrose are natural lyoprotectants. Trehalose is produced by a variety of plant, fungi, and invertebrate animals that remain in a state of suspended animation during periods of drought (also known as anhydrobiosis).

Applications of freeze-drying

Pharmaceutical and biotechnology

Pharmaceutical companies often use freeze-drying to increase the shelf life of products, such as vaccines and other injectables. By removing the water from the material and sealing the material in a vial, the material can be easily stored, shipped, and later reconstituted to its original form for injection. Another example from the pharmaceutical industry is the use of freeze drying to produce tablets or wafers. The advantage of which is less excipient and a rapidly absorbed and easily administered dosage form.

Food industry

Freeze-dried coffee, a form of instant coffee.

Freeze-drying is used to preserve food and make it very lightweight. The process has been popularized in the forms of freeze-dried ice cream, an example of astronaut food. It is also popular and convenient for hikers because the reduced weight allows them to carry more food and reconstitute it with available water. Instant coffee issometimes freeze-dried, despite the high costs of the freeze-driers used. The coffee is often dried by vaporization in a hot air flow, or by projection on hot metallic plates. Freeze-dried fruit is used in some breakfast cereal. Culinary herbs are also freeze- dried, although air-dried herbs are far more common and less expensive. However, the freeze-drying process is used more commonly in the pharmaceutical industry.

Text 14. Fermentation

Fermentation in food processing typically is the conversion of carbohydrates to alcohols and carbon dioxide or organic acids using yeasts, bacteria, or a combination thereof, under anaerobic conditions. A more restricted definition of fermentation is the chemical conversion of sugars into ethanol. The science of fermentation is known as zymurgy.

Fermentation usually implies that the action of microorganisms is desirable, and the process is used to produce alcoholic beverages such as wine, beer, and cider. Fermentation is also employed in the leavening of bread, and for preservation techniques to create lactic acid in sour foods such as sauerkraut, dry sausages, kimchi and yogurt, or vinegar (acetic acid) for use in pickling foods.

Natural fermentation precedes human history. Since ancient times, however, humans have been controlling the fermentation process. The earliest evidence of winemaking dates from eight thousand years ago, in Georgia, in the Caucasus area. Seven- thousand-year-old jars containing the remains of wine have been excavated in the Zagros Mountains in Iran, which are now on display at the University of Pennsylvania.There is strong evidence that people were fermenting beverages in Babylon circa 5000 BC, ancient Egypt circa 3150 BC, pre-Hispanic Mexico circa 2000 BC, and Sudan circa 1500 BC. There is also evidence of leavened bread in ancient Egypt circa 1500 BC and of milk fermentation in Babylon circa 3000 BC.

French chemist Louis Pasteur was the first known zymologist, when in 1854 he connected yeast to fermentation. Pasteur originally defined fermentation as "respiration without air". Pasteur performed careful research and concluded;

"I am of the opinion that alcoholic fermentation never occurs without simultaneous organization, development and multiplication of cells.... If asked, in what consists the chemical act whereby the sugar is decomposed ... I am completely ignorant of it." When studying the fermentation of sugar to alcohol by yeast, Louis Pasteur concluded that the fermentation was catalyzed by a vital force, called "ferments," within the yeast cells. The "ferments" were thought to function only within living organisms. "Alcoholic fermentation is an act correlated with the life and organization of the yeast cells, not with the death or putrefaction of the cells," he wrote. Nevertheless, it was known that yeast extracts ferment sugar even in the absence of living yeast cells. While studying this process in 1897, Eduard Buchner of Humboldt University of Berlin, Germany, found that sugar was fermented even when there were no living yeast cells in the mixture, by a yeast secretion that he termed zymase. In 1907 he received the Nobel Prize in Chemistry for his research and discovery of "cell-free fermentation." One year prior, in 1906, ethanol fermentation studies led to the early discovery of NAD+.

Uses

The primary benefit of fermentation is the conversion of sugars and other carbohydrates, e.g., converting juice into wine, grains into beer, carbohydrates into carbon dioxide to leaven bread, and sugars in vegetables into preservative organic acids.

Food fermentation has been said to serve five main purposes:

Enrichment of the diet through development of a diversity of flavors, aromas, and textures in food substrates;

Preservation of substantial amounts of food through lactic acid, alcohol, acetic acid and alkaline fermentations;

Biological enrichment of food substrates with protein, essential amino acids, essential fatty acids, and vitamins;

Elimination of antinutrients;

A decrease in cooking times and fuel requirements;

Some fermentation products (e.g., fusel alcohol) are deleterious.

Text 15. Curing

Curing refers to various food preservation and flavoring processes, especially of meat or fish, by the addition of a combination of salt, sugar, nitrates or nitrite. Many curing processes also involve smoking.

Food curing dates back to ancient times, both in the form of smoked meat and as salt- cured meat. Although the ancient people curing the meat did not know this, it was actually nitrates present in the salt that helped the curing process. The Native Americans used to hang their meat at the top of their teepees to increase the amount of smoke coming into contact with the food.

Chemical actions of salt

According to the Oklahoma Cooperative Extension Service, salt (sodium chloride; chemical formula: NaCl) is the "primary ingredient used in meat curing". Salt works by dehydrating the meat, thus preventing the growth of bacteria, and it creates an inhospitable osmotic pressure through the cell wall of the bacterium. This triggers the beneficial bacteria, including lactobacillus acidophilus, to grow in the new environment and lower the pH to approximately 4.5. Doing this requires a concentration of salt of nearly 20%. In addition, salt causes the soluble meat proteins to come to the surface of the meat cut and then solidify, which is what gives sausage its characteristic skin. Finally, salt slows the oxidation process, effectively preventing the meat from going rancid. Sugar

The sugar added to meat for the purpose of curing it comes in many forms, including honey, corn syrup solids, and maple syrup. However, with the exception of bacon, it does not contribute much to the flavor, but it does alleviate the harsh flavor of the salt. Sugar also contributes to the growth of beneficial bacteria like Lactobacillus by feeding them.

Nitrates and nitrites

Nitrates and nitrites not only help kill bacteria, but also produce a characteristic flavor and give meat a pink or red colour.

Intestine for sausage making

Fresh sausages are simply seasoned ground meats that are cooked before serving. Fresh sausages normally do not use cure (Prague powder # 1 ) although cure can be used if desired. In addition fresh sausages typically do not use smoke flavors, although liquid smoke can be used. Fresh sausages are never smoked in a cold smoker because of the danger of botulism.

The primary seasoning agents in fresh sausages are salt and sugar along with various savory herbs and spices, and often vegetables, including onion and garlic.

A British fresh sausage typically contains around 10% butcher's rusk, 10% water, 2.5% seasoning, and 77.5% meat. At point of sale British sausages will often be labelled as "actual meat content X%". As meat can be fatty or lean, the X% is calculated using reference tables with the intention to give a fairer representation of the "visual lean" meat content.

Cured dry sausages

Cured dry sausages are prepared in a fashion similar to cured cooked sausages. The major difference is that Prague powder #2 will be used in place of Prague powder #1. In addition, certified meats must be used. Since these products are never heated to a temperature that can kill trichinosis, it is necessary to accomplish this by other methods. The usual method is via freezing. Pork may be rendered acceptable for use in dry sausages by freezing it using the following guidelines:5 °F (-15 °C) 20-30 days

--10 °F (-23 °C) 10-20 days -20 °F (-29 °C) 6-12 days

The specific regulations are quite complex and are beyond the scope of this article. They depend on the thickness of the cuts of meat, the packaging method, and other factors. In addition there are very specific requirements as to the times in the drying rooms and the temperatures in the smoke rooms.

While it is quite feasible for the small sausage kitchen or hobbyist to produce excellent cured dry sausages, a great deal of technical information is required. Alternatively, certified pork can be simply purchased.

Text 16. Aspic

An aspic with chicken and eggs.

Aspic is a dish in which ingredients are set into a gelatin made from a meat stock.. Similar dishes, made with commercial gelatin mixes instead of stock, are usually called gelatin salads. When cooled, stock that is made from meat congeals because of the natural gelatin found in the meat. The stock can be clarified with egg whites, and then filled and flavored just before the aspic sets. Almost any type of food can be set into aspics. Most common are meat pieces, fruits, or vegetables. Aspics are usually served on cold plates so that the gel will not melt before being eaten. A meat jelly that includes cream is called a chaud-froid.

Nearly any type of meat can be used to make the gelatin: pork, beef, veal, chicken, turkey, or fish. Gelatin is also found in cartilage. The aspic may need additional gelatin in order to set properly. Veal stock provides a great deal of gelatin; in making stock, veal is often included with other meat for that reason. Fish consommйs usually have too little natural gelatin, so the fish stock may be double-cooked or supplemented. Since fish gelatin melts at a lower temperature than gelatins of other meats, fish aspic is more delicate and melts more readily in the mouth.

Vegetables and fish stocks need gelatin to create a mold.

Historically, meat jellies were made before fruit and vegetable jellies. By the Middle Ages at the latest, cooks had discovered that a thickened meat broth could be made into a jelly. A detailed recipe for aspic is found in Le Viandier, written in around 1375.

In the 18th century, Marie-Antoine Carкme created chaud froid in France. Chaud froid means "hot cold" in French, referring to foods that were prepared hot and served cold. Aspic was used an chaud froid sauce in many cold fish and poultry meals. The sauce added moisture and flavor to the food. Carкme invented various types of aspic and ways of preparing it.

Aspic, when used to hold meats, prevents them from becoming spoiled. The gelatin keeps out air and bacteria, keeping the cooked meat fresh.

Aspic came into prominence in America in the early 20th century. By the 1950s, meat aspic was a popular dinner staple throughout the United States as were other gelatin-based dishes such as tomato aspic. Cooks used to show off aesthetic skills by creating inventive aspics.

Uses

Aspic can also be referred as aspic jelly. Aspic jelly may be colorless (white aspic) or contain various shades of amber. Aspic can be used to protect food from the air, give food more flavor, or as a decoration.

There are three types of aspic textures: delicate, sliceable, and inedible. The delicate aspic is soft. The sliceable aspic must be made in a terrine or in a aspic mold. It is more firm than the delicate aspic. The inedible aspic is never for consumption. It is usually for decoration. Aspic is often used to glaze food pieces in food competitions to make the food glisten and make it more appealing to the eye. Foods dipped in aspic have a lacquered finish for a fancy presentation. Aspic can be cut into various shapes and be used as a garnish for deli meats.

Outside of the U.S.

In Poland (known as "galareta"), in Ukraine (known as "studinets"), Latvia (similarly known as "galerts"), in Russia (known as "kholodets"), in Serbia (known as "pihtije"), in Croatia (known as "hladetina"), in Hungary (known as "kocsonya") and in Romania (known as "piftie" or "rаcituri") aspic often takes the form of pork jelly, and it is popular around the Christmas and Easter Holidays. In Asia, among the Newars of Kathmandu Valley, Nepal, buffalo meat jelly is a major component of the winter festivity gourmet. It is eaten in combination with fish aspic, which is made from dried fish and buffalo meat stock, soured, and contains a heavy mix of spices and condiments.

In popular culture

"Life is a bitter aspic." - Wallace Stevens.

"Well, if it doesn't jell, it isn't aspic, and this ain't jellin'!" - Milton Arbogast in the film Psycho

Larks' Tongues in Aspic, King Crimson album title, and the name of four songs on this and other King Crimson albums.

A Dandy in Aspic, the final film by director Anthony Mann

Julie and Julia - A scene deals with Julie's failed attempt to make an aspic from Julia Child's Mastering the Art of French Cooking.

Dinner at Eight - In this 1933 George Cukor social comedy film, Millicent Jordan (Billie Burke) ventures a considerable emotional investment in the lion-shaped aspic she has had prepared for the eponymous meal.

Coronation Street - Hilda Ogden prepares dishes for her 'posh' house party and reads that 'eggs in aspic' is the perfect party dish. However she isn't quite sure what 'aspic' is and uses lemon flavoured jelly.

Delicacies (album), first song on the album of Simian Mobile Disco is titled "Aspic".

Text 17. Potted meat

A potted meat food product or potted meat is a food made using a method of food preservation -canning, consisting of cooked meat product, seasoned, often creamed, minced, or ground, which is filled into cans, sealed and heat processed in a retort to commercial sterility.

Various meats such as beef, pork, chicken, turkey and variety (nonskeletal) meats are used. It is produced internationally as a source of affordable meat. Its long shelf life and precooking makes it suitable for emergency food supplies, and for military and camping uses, although the high content of fat, protein, and/or preservatives may make it unsuitable for frequent consumption. The final product typically has a spreadable consistency, and typically contains high amounts of salt, as a preservative.

Reputation

Canned meats have a mixed reputation on account of the taste, texture, ingredients, preparation and nutrition. The canning process produces a product with a generally homogeneous texture and flavor. The low-cost ingredients used also affect the quality. For example, mechanically separated chicken or turkey is a paste-like product made by forcing crushed bone and tissue through a sieve to separate bone from tissue. In the United States, mechanically separated poultry has been used in poultry products since 1969, after the National Academy of Sciences found it safe for use. On November 3, 1995, the Food Safety and Inspection Service (FSIS) of the U.S. Department of Agriculture (USDA) published a final rule in the Federal Register (see 60 FR 55962) on mechanically separated poultry, stating that it was safe to use without restrictions 1] However, it must be labeled as "mechanically separated chicken or turkey" in the ingredient statement. The final rule became effective on November 4, 1996.

Ingredients

Armour Star: Mechanically separated chicken, beef tripe, partially defatted cooked beef fatty tissue, beef hearts, water, partially defatted cooked pork fatty tissue, salt, and less than 2 percent: mustard, natural flavorings, dried garlic, dextrose, sodium erythorbate, and sodium nitrite.

Hormel: Beef tripe, mechanically separated chicken, beef hearts, partially defatted cooked beef fatty tissue, meat broth, vinegar, salt, flavoring, sugar, and sodium nitrite.

Libby's: Mechanically separated chicken, pork skin, partially defatted cooked pork fatty tissue, partially defatted cooked beef fatty tissue, vinegar, less than 2% of: salt, spices, sugar, flavorings, sodium erythorbate and sodium nitrite.

Text 18. Food irradiation

Processing of food by ionizing radiation

By irradiating food, depending on the dose, some or all of the harmful bacteria and other pathogens present are killed. This prolongs the shelf-life of the food in cases where microbial spoilage is the limiting factor. Some foods, e.g., herbs and spices, are irradiated at sufficient doses (five kilograys or more) to reduce the microbial counts by several orders of magnitude; such ingredients do not carry over spoilage or pathogen microorganisms into the final product. It has also been shown that irradiation can delay the ripening of fruits or the sprouting of vegetables.

Furthermore, insect pests can be sterilized (be made incapable of proliferation) using irradiation at relatively low doses. In consequence, the United States Department of Agriculture (USDA) has approved the use of low-level irradiation as an alternative treatment to pesticides for fruits and vegetables that are considered hosts to a number of insect pests, including fruit flies and seed weevils; the U.S. Food and Drug Administration (FDA) has cleared among a number of other applications the treatment of hamburger patties to eliminate the residual risk of a contamination by a virulent E. coli. The United Nations Food and Agricultural Organization (FAO) has passed a motion to commit member states to implement irradiation technology for their national phytosanitary programs; the General assembly of the International Atomic Energy Agency (IAEA) has urged to make wider use of the irradiation technology. Additionally, the USDA has made a number of bi-lateral agreements with developing countries to facilitate the imports of exotic fruits and to simplify the quarantine procedures.

The European Union has regulated processing of food by ionizing radiation in specific directives since 1999; the relevant documents and reports are accessible online. The "implementing" directive contains a "positive list" permitting irradiation of only dried aromatic herbs, spices, and vegetable seasonings. However, any Member State is permitted to maintain previously granted clearances or to add new clearance as granted in other Member States, in the case the EC's Scientific Committee on Food (SCF) has given a positive vote for the respective application. Presently, six Member States (Belgium, France, Italy, Netherlands, Poland, United Kingdom) have adopted such provisions.

Because of the "Single Market" of the EC, any food -- even if irradiated -- must be allowed to be marketed in any other Member State even if a general ban of food irradiation prevails, under the condition that the food has been irradiated legally in the state of origin. Furthermore, imports into the EC are possible from third countries if the irradiation facility had been inspected and licensed by the EC and the treatment is legal within the EC or some Member state.

The Scientific Committee on Food (SCF) of the EC has given a positive vote on eight categories of food to be irradiated. However, in a compromise between the European Parliament and the European Commission, only dried aromatic herbs, spices, and vegetable seasonings can be found in the positive list. The European Commission was due to provide a final draft for the positive list by the end of 2000; however, this failed because of a veto from Germany and a few other Member States. In 1992, and in 1998 the SCF voted "positive" on a number of irradiation applications that had been allowed in some member states before the EC Directives came into force, to enable those member states to maintain their national authorizations.

In 2003, when Codex Alimentarius was about to remove any upper dose limit for food irradiation, the SCF adopted a "revised opinion", which, in fact, was a reconfirmation and endorsement of the 1986 opinion. The opinion denied cancellation of the upper dose limit, and required that before the actual list of individual items or food classes (as in the opinions expressed in 1986, 1992 and 1998) can be expanded, new individual studies into the toxicology of each of such food and for each of the proposed dose ranges are requested. The SCF has subsequently been replaced by the new European Food Safety Authority (EFSA), which has not yet ruled on the processing of food by ionizing radiation.

Other countries, including New Zealand, Australia, Thailand, India, and Mexico, have permitted the irradiation of fresh fruits for fruit fly quarantine purposes, amongst others. Such countries as Pakistan and Brazil have adopted the Codex Alimentarius Standard on Irradiated Food without any reservation or restriction: i.e., any food may be irradiated to any dose.

Technologies

Electron irradiation

Electron irradiation uses electrons accelerated in an electric field to a velocity close to the speed of light. Electrons are particulate radiation and, hence, have cross section many times larger than photons, so that they do not penetrate the product beyond a few inches, depending on product density. Electron facilities rely on substantial concrete shields to protect workers and the environment from radiation exposure.

Gamma irradiation

Gamma radiation is radiation of photons in the gamma part of the electromagnetic spectrum. The radiation is obtained through the use of radioisotopes, generally cobalt-60 or, in theory, caesium-137. Cobalt-60 is bred from cobalt-59 using neutron irradiation in specifically designed nuclear reactors. Caesium-137 is recovered during the processing of spent nuclear fuel. Because this technology -- except for military applications -- is not commercially available, insufficient quantities of it are available on the global isotope markets for use in large scale, commercial irradiators. Presently, caesium-137 is used only in small hospital units to treat blood before transfusion to prevent Graft-versus-host disease.

Food irradiation using Cobalt-60 is the preferred method by most processors, because the deeper penetration enables administering treatment to entire industrial pallets or totes, reducing the need for material handling. A pallet or tote is typically exposed for several minutes to hours depending on dose. Radioactive material must be monitored and carefully stored to shield workers and the environment from its gamma rays. During operation this is achieved by substantial concrete shields. With most designs the radioisotope can be lowered into a water-filled source storage pool to allow maintenance personnel to enter the radiation shield. In this mode the water in the pool absorbs the radiation. Other uncommonly used designs feature dry storage by providing movable shields that reduce radiation levels in areas of the irradiation chamber.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

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.

Modified atmosphere

Modifying 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 (02) concentration and increase the carbon dioxide (C02) 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 by one of two methods; either using a block of dry ice placed in the bottom and the can is filled with grain or the container can be purged from the bottom by gaseous carbon dioxide from a cylinder or bulk supply vessel.

Carbon dioxide prevents insects, and depending on concentration, mold, and oxidation from damaging the grain. Grain stored in this way can remain edible for fiv One variant of gamma irradiators keeps the Cobalt-60 under water at all times and lowers the product to be irradiated under water in hermetic bells. No further shielding is required for such designs.

X-ray irradiation

Similar to gamma radiation, X-rays are photon radiation of a wide energy spectrum and an alternative to isotope based irradiation systems. X-rays are generated by colliding accelerated electrons with a dense material (target) such as tantalum or tungsten in a process known as bremsstrahlung-conversion. X-ray irradiators are scalable and have deep penetration comparable to Co-60, with the added effect of using an electronic source that stops radiating when switched off. They also permit dose uniformity. However, these systems generally have low energetic efficiency during the conversion of electron energy to photon radiation requiring much more electrical energy than other systems. Like most other types of facilities, X-ray systems rely on concrete shields to protect the environment and workers from radiation.

Nominal X-ray energy is usually limited to 5 MeV; however, USA has provisions for up to 7.5 MeV, which increases conversion efficiency. Another development is the availability of electron accelerators with extremely high power output, up to 1,000 kW beam. At a conversion efficiency of up to 12%, the X-ray power may reach (including filtering and other losses) 100 kW; This power would be equivalent to a gamma facility with Co-60 of about 6.5 MCi.

Text 19. 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 understanding how long food can be stored, how stable it will remain, and in determining food texture. The acceptability of food products to the consumer is often determined by food texture, such as how spreadable and creamy a food product is. Food rheology is important in quality control during food manufacture and processing. Food rheology terms have been noted since ancient times. In ancient Egypt bakers judged the consistency of dough by rolling it in their hands.

There is a large body of literature on food rheology because the study of food rheology entails unique factors beyond an understanding of the basic rheological dynamics of the flow and deformation of matter. Food can be classified according to its rheological state, such as a solid, gel, liquid, emulsion with associated rheological behaviors, and its rheological properties can be measured. These properties will affect the design of food processing plants, as well as shelf life and other important factors, including sensory properties that appeal to consumers. Because foods are structurally complex, often a mixture of fluid and solids with varying properties within a single mass, the study of food rheology is more complicated than study in fields such as the rheology of polymers.

The most important factor in food rheology is consumer perception of the product. This perception is affected by how the food looks on the plate as well as how it feels in the mouth, or "mouthfeel". Mouthfeel is influenced by how food moves or flows once it is in a person's mouth and determines how desirable the food is seen to be.

Text 20. Nutraceutical

Nutraceutical, a term combining the words "nutrition" and "pharmaceutical", is a food or food product that provides health and medical benefits, including the prevention and treatment of disease [citation needed]. Such products may range from isolated nutrients, dietary supplements and specific diets to genetically engineered foods, herbal products, and processed foods such as cereals, soups, and beverages. With recent developments in cellular-level nutraceutical agents, researchers, and medical practitioners are developing templates for integrating and assessing information from clinical studies on complimentary and alternative therapies into responsible medical practice. The term nutraceutical was originally defined by Dr. Stephen L. DeFelice, founder and chairman of the Foundation of Innovation Medicine (FIM), Crawford, New Jersey. Since the term was coined by Dr. DeFelice, its meaning has been modified by Health Canada which defines nutraceutical as: a product isolated or purified from foods, and generally sold in medicinal forms not usually associated with food and demonstrated to have a physiological benefit or provide protection against chronic disease. Examples: beta-carotene, lycopene The definition of nutraceutical that appears in the latest edition of the Merriam-Webster Dictionary is as follows: A food stuff (as a fortified food or a dietary supplement)that provides health benefits. Nutraceutical foods are not subject to the same testing and regulations as pharmaceutical drugs.The American Nutraceutical Association works with the Food & Drug Administration in consumer education, developing industry and scientific standards for products and manufacturers, and other related consumer protection roles. The FDA provides a list of dietary supplement companies receiving warning letters about their products.

Market and demand

Nearly two-thirds of the American population takes at least one type of nutraceutical health product. The use of nutraceuticals, as an attempt to accomplish desirable therapeutic outcomes with reduced side effects, as compared with other therapeutic agents has met with great monetary success. The preference for the discovery and production of nutraceuticals over pharmaceuticals is well seen in pharmaceutical and biotech companies. Some of the pharmaceutical and biotech companies, which commit major resources to the discovery of nutraceuticals include Monsanto, American Home Products, Dupont, Abbott Laboratories, Warner-Lambert, Johnson & Johnson, Novartis, Metabolex, Genzyme Transgenic, PPL Therapeutics, and

Interneuron.The nutraceutical industry in the US is about $86 billion. This figure is slightly higher in Europe and, in Japan, represents approximately a quarter of the $6 billion total annual food sales. 47% of the Japanese population consume nutraceuticals. Even without specific financial figures, business reports continually suggest that the market is consistently growing.

One possible explanation for the growth of nutraceuticals in the United States is the aging baby-boomer population. As the average age of the citizens continues to rise, the population increases its focus on health and wellness. By halfway through the 21st century, there could be almost 142 million Americans over the age of 50, based on a projected population of nearly 400 million citizens.

Although the price of some nutraceuticals may drop as generic products make their way into the market, people's dependence on these products and their increasing availability suggests that the growth of the market shall remain stable.

Food as medicine

Considered a father of Western medicine, Hippocrates advocated the healing effects of food.

The Indians, Egyptians, Chinese, and Sumerians are just a few civilizations that have provided evidence suggesting that foods can be effectively used as medicine to treat and prevent disease. Ayurveda,the 5 thousand year old ancient indian health science have mentioned benefits of food for therapautic purpose.Documents hint that the medicinal benefits of food have been explored for thousands of years. Hippocrates, considered by some to be the father of Western medicine, said that people should "Let food be thy medicine."

The modern nutraceutical market began to develop in Japan during the 1980s. In contrast to the natural herbs and spices used as folk medicine for centuries throughout Asia, the nutraceutical industry has grown alongside the expansion and exploration of modern technology.

New research conducted among food scientists show that there is more to food science than what was understood just a couple decades ago. Until just recently, analysis of food was limited to the flavor of food (sensory taste and texture) and its nutritional value (composition of carbohydrates, fats, proteins, water, vitamins and minerals). However, there is growing evidence that other components of food may play an integral role in the link between food and health.

These chemical components are derived from plant, food, and microbial sources, and provide medicinal benefits valuable to long-term health. Examples of these nutraceutical chemicals include probiotics, antioxidants, and phytochemicals.

Nutraceutical products were considered alternative medicine for many years. Nutraceuticals have become a more mainstream supplement to the diet, now that research has begun to show evidence that these chemicals found in food are often effective when processed effectively and marketed correctly.

Text 21. Pasteurization

Pasteurization is a process of heating a food, usually liquid, to a specific temperature for a definite length of time, and then cooling it immediately. This process slows microbial growth in food. The process of heating wine to preserve it longer was known in China since AD.l 117, and is documented in Japan in 1568 in the diary Tamonin-nikki, but the modern version was created by the French chemist and microbiologist Louis Pasteur, after whom it is named. The first pasteurization test was completed by Louis Pasteur and Claude Bernard on April 20, 1864. The process was originally conceived as a way of preventing wine and beer from souring.

Pasteurization aims to reduce the number of viable pathogens so they are unlikely to cause disease (assuming the pasteurized product is stored as indicated and consumed before its expiration date). Commercial-scale sterilization of food is not common because it adversely affects the taste and quality of the product. Certain food products, like dairy products, are superheated to ensure pathogenic microbes are destroyed.

Products that can be pasteurized: Almonds, Apple cider, Beer, Bread, Canned food, Cheese, Cornbread, Crabs, Cream, Eggs, Grapefruit juice, Honey (not necessary unless it is diluted), Juice, Maple syrup, Milk, Chocolate milk, Orange juice, Palm wine, Pomegranate juice, Ready Meal, Soy sauce, Sports drinks, Tobacco, Vinegar, Vitamin water, Water, Wine.

Pasteurization of milk

Pasteurization is typically associated with milk; pasteurization of milk was first suggested by Franz von Soxhlet in 1886. It is the main reason for milk's extended shelf life. High Temperature Short Time (HTST) pasteurised milk typically has a refrigerated shelf life of two to three weeks, whereas ultra pasteurised milk can last much longer, sometimes two to three months. When ultra heat treatment (UHT) is combined with sterile handling and container technology (such as aseptic packaging), it can even be stored unrefrigerated for 6-9 months, although superheated milk's flavor is impaired, and it may lose some nutritional value.

Pasteurization typically uses temperatures below boiling since at very high temperatures casein micelles will irreversibly aggregate, or "curdle." There are two main types of pasteurization used today: High Temperature/Short Time (HTST) and "Extended Shelf Life (ESL)" treatment. Ultra-high temperature (UHT or ultra-heat treated) is also used for milk treatment. In the HTST process, milk is forced between metal plates or through pipes heated on the outside by hot water, and is heated to 71.7 °C (161 °F) for 15-20 seconds. UHT processing holds the milk at a temperature of 135 °C (275 °F) for a minimum of one second. ESL milk has a microbial filtration step and lower temperatures than UHT. Milk simply labeled "pasteurised" is usually treated with the HTST method, whereas milk labeled "ultra-pasteurised" or simply "UHT" has been treated with the UHT method.

Pasteurization methods are usually standardized and controlled by national food safety agencies (such as the USDA in the United States and the Food Standards Agency in the United Kingdom). These agencies require milk to be HTST pasteurized in order to qualify for the "pasteurization" label. There are different standards for different dairy products, depending on the fat content and the intended usage. For example, the pasteurization standards for cream differ from the standards for fluid milk, and the standards for pasteurizing cheese are designed to preserve the phosphatase enzyme, which aids in cutting.

In Canada, all milk produced at a processor and intended for consumption must be pasteurized, legally requiring it to be heated to at least 72 degrees Celsius for at least 16 seconds and then cooling it to 4 degrees Celsius. This ensures that any harmful bacteria are destroyed.

The HTST pasteurization standard was designed to achieve a 5-log reduction, killing 99.999% of the number of viable micro-organisms in milk. This is considered adequate for destroying almost all yeasts, mold, and common spoilage bacteria and also to ensure adequate destruction of common pathogenic heat-resistant organisms (including Mycobacterium tuberculosis, which causes tuberculosis but not Coxiella burnetii, which causes Q fever). HTST pasteurization processes must be designed so that the milk is heated evenly, and no part of the milk is subject to a shorter time or a lower temperature.

A process similar to pasteurization is thermization, which uses lower temperatures to kill bacteria in milk. It allows a milk product, such as cheese, to retain more of the original taste, but thermized foods are not considered pasteurized by food regulators.

Effectiveness of pasteurization

Milk pasteurization has been subject to increasing scrutiny in recent years, due to the discovery of pathogens that are both widespread and heat resistant (able to survive pasteurization in significant numbers). One of these pathogens, Mycobacterium avium subsp. paratuberculosis (MAP), is linked to Crohn's Disease. Researchers have developed more sensitive diagnostics, such as real-time PCR and improved culture methods that have enabled them to identify pathogens in pasteurised milk.