Chapter 19_Food Quality and Safety

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Chapter19:Food Quality and Safety

Edited by Dr. Mir F. Ali 1

C h a p t e r 1 9 – F o o d Q u a l i t y a n d S a f e t y

Irradiation is the process by which an object is exposed to radiation. Food irradiation, anuclear technique for food preservation, is the result of decades of research conducted in various parts of the world, exploring the possibilities of using radiation as a way of

alleviating the food deficiencies.

Food irradiation is an industrial process and must be carried out in an industrialirradiation facility. This consists of a large shielded chamber into which a field of ionizingenergy can be introduced from a suitable source. The shielding confines the ionizingenergy field, protecting nearby living things from harm. Processing consists of conveyingthe food packages into the chamber and leaving them there for a specified period of time,to absorb a carefully controlled dose of radiation. To complete the process the food is

then conveyed out of the chamber. The food can immediately be utilized for whateverpurpose it is intended.

All commercial irradiators have four primary components, a source of radiation, amethod of product conve yance, “shields” to prevent exposure of personnel and theenvironment to radiation and safety systems. Ionizing radiation is penetrating energy andthus, products are usually irradiated after they are fully packaged. Below is a descriptionof the four types of irradiators that are commercially available or in use today for food

http://en.wikipedia.org/wiki/Radiation



http://www.cifst.ca/default.asp?id=879


http://www.fipa.us/q%26a.pdf







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processing. The choice of which irradiator is most cost effective for a particular productdepends on the type of product, how it is packaged, the product dose, dose uniformity requirements and, most important, logistics.

1. ELECTRON BEAM IRRADIATOR (Employing a RadiationChamber):The source of electron beams is an “accelerator”. Accelerators generate and accelerateelectrons very fast towards the food product being irradiated. Because electrons havemass, they can only penetrate about 1.5 inches (3.8 cm) into a typical food product orabout 3.5 inches (8.9 cm) if the food product is irradiated on both sides. Electrons alsohave an electric charge. This charge allows the stream of accelerated electrons to bescanned by magnets to track across the product. A commercial food electron beamirradiator accelerates the electrons to energy of up to 10,000,000 electron volts (10 MeV).

Electron beam irradiators typically use massive concrete, steel or lead shielding. ElectronBeam accelerators can be turned on and off. Safety interlocks ensure that a person cannotenter the radiation chamber where the food is being irradiated when the accelerator is“on”. Product is usually passed through the scanned “beam” on roller type conveyors;



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2. GAMMA IRRADIATOR (Employing a Radiation Chamber):The source of photons in a gamma irradiator is cobalt-60. Unlike electron beams that are

generated on site using electric power, cobalt-60 is produced off site in nuclear reactorsand transported in special shipping containers (“casks”) to the site. Cobalt-60 is a solidradioactive metal that is contained in two welded encapsulations of stainless steelcreating a “Sealed Source”. The sealed source contains the “Radioactive” cobalt-60, butallows the photons “Radiation” to pass through the encapsulations and ultimately into thefood product. Because Cobalt-60 photons have no mass, they can penetrate more than 24inches (60 cm) of food product if irradiated on both sides. Gamma irradiators that employ a radiation chamber typically have shields made out of massive concrete or steel. Cobalt-60 continuously emits radiation and cannot be turned “off”. To allow personnel access tothe chamber, the source is lowered into a storage pool of shielding water when it is not

being used to irradiate product. The shielding water does not become radioactive. Safety interlocks are used to assure that a person cannot enter the chamber when the source isnot in the stored position (at the bottom of the pool of water). Hanging carriers, totes androller conveyors are typically employed to move the product through the chamber;



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3. GAMMA IRRADIATOR (Underwater):Like the radiation chamber irradiator above, an underwater gamma irradiator uses

cobalt-60. Unlike a radiation chamber irradiator, an underwater irradiator stores thecobalt-60 permanently at the bottom of a pool of water. Instead of raising the cobalt-60into a shielded chamber, the product, placed in water free containers, is lowered to thebottom of the pool adjacent to the cobalt-60 to receive a dose of radiation. The water actsas the shield. The shielding water does not become radioactive. No above groundshielding or radiation chamber is present. There is no need for interlocks to preventpersonnel from entering a radiation chamber when the cobalt-60 is present, becausethere is no radiation chamber. Typically, the product is loaded into water free containersand the containers are lowered/raised using a hoist mechanism; and

4. X-RAY IRRADIATOR (Employing a Radiation Chamber): X-rays are photons and have similar properties to gamma rays emitted by cobalt-60. X-rays are generated by using an electron beam accelerator (above) and converting theelectron beam (up to 7.5 MeV) to photons by accelerating the electrons into a high-density material such as tungsten, steel or tantalum. The sudden deceleration of theelectrons generates x-rays and waste heat.



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The creating of the radiation is very similar to an electron beam irradiator (above),including the ability to be turned on and off. The shielding and product conveyance are

similar to that of a chamber type gamma irradiator (above). The safety interlocks aresimilar to both electron beam and chamber type gamma irradiators. The advantages of x-rays over electron beams are that they have good product penetration (over 24 inches or60 cm of food product if irradiated on both sides). The advantages of x-rays over bothtypes of gamma irradiators are that they do not require a shielding storage pool.However, there is a substantial loss of energy during the conversion process. Thus, itsuffers a severe cost disadvantage when compared to other types of irradiators for thesame product volume throughput.

Various authors believe that food losses through spoilage after harvest can be estimated

equivalent to the production from 12 million acres of land, or 33 million tons of grain. Another estimate is that the world food supply could be increased by 25- 30 percent, if post-harvest losses could be avoided. Such losses represent losses in soil fertility, manuallabour and monetary expenditure as well as loss of product. Losses occur especially in thetropical regions where most developing countries are situated. Naturally, these lossescould either be the result of the available food preservation technologies in thosecountries do not function efficiently in such environments or simply because they do notlend themselves to the habits of food consumption in most developing countries. People

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in such countries are accustomed to buying fresh food for immediate consumption athome. They would welcome any new technology, which would keep food fresh for alonger time.

Post-harvest losses in countries of the Asian region, for example, are estimated at 30percent for grains, 20 percent to 40 percent for fruits and vegetables, and up to 50 percentfor fish. In Africa, a conservative estimate shows that a minimum of 20 percent of totalfood production is lost after harvest. Losses of perishable items such as fruits, vegetables,and fish, for example, are even higher than 50 percent. The US National Academy of Sciences has estimated that the minimum post-harvest food losses in developingcountries amounted to more than 100 million tonnes at a value surpassing US $10 billionin 1985.

Food-borne diseases continue to affect adversely the health and productivity of populations in most countries, especially in developing ones. Contamination of food – especially of animal origin – with microorganisms, particularly pathogenicnonsporeforming bacteria, as well as infection with parasitic helminthes and protozoa,are important public health problems and causes of human suffering and malnutrition. According to the World Health Organization (WHO), infectious and parasitic diseasesrepresented the most frequent cause of death (35 percent) worldwide in 1990, with themajority of deaths occurring in developing countries. These diseases include malaria,






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diarrhea, tuberculosis, measles, pertussis, and schistosomiasis. Diarrheal disease causedabout 25 percent of deaths in developing countries. It is estimated that in possibly up to70 percent cases food is the vehicle for transmission of diarrheal diseases.

Moreover, recently 15 countries in Latin America have reported some 400 000 cases of cholera and more than 4000 deaths. The most important cause of transmission of thedisease was the consumption of contaminated water and food. Elsewhere, 7 millionpeople in the northeastern provinces of Thailand, 3 million in the Republic of Korea, andmillions more in China are infected by liver fluke parasites from consumption of rawfreshwater fish. The economic losses caused by these diseases in these countries areestimated to be hundreds of millions of US dollars annually.

Consequently, food safety has to be a major consideration for consumer acceptance and

willingness to pay for irradiated products. For instance, according to a report, publichealth in the USA is burdened with foodborne diseases and 76 million cases are reportedeach year, which is translated to:

1. 1 in 4 Americans gets a foodborne disease each year;2. 1 in 1000 Americans is hospitalized each year; and3. $6.5 billion in medical and other costs.



http://www.ilsi.org.ar/contactos/ILSI_Argentina_Comite_Bioseguridad/







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The figures presented in the graph (Figure 03) about illness, hospitalization, and deaths,illustrate the impact of foodborne diseases like E.coli0157, Listeria, and Salmonella.

It is reported that if 50 percent of meat and poultry were to be irradiated in the USA, theimpact will be:

1. 880,000 fewer cases;2. 350 fewer deaths; and3. 8,500 fewer hospitalizations.

While there appear to be a consensus about the fact that it is better to conserve what isproduced than to produce more to compensate for subsequent losses, demand is alsogrowing in both the developed and the developing countries for food which is wholesomeand which has a long shelf life. There are obvious reasons for using radiation to preserve

food and agricultural produce, and hence to alleviate the world’s food shortage and toproduce safe foods. There is a strong possibility that in addition to practicingconservation, more food will have to be produced in order to be in the position to feedthe growing global population.






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Irradiation food processing, has several uses, most of which prolong the useful life of foods in the condition in which they have been obtained. Food irradiation processing

induces virtually no temperature rise in the treated products, and is therefore oftentermed as a “cold” process. Fish, fruits, and vegetables remain fresh, and the physical stateof frozen or dried commodities is unchanged. The agents causing spoilage (bacteria,insects) are reduced in numbers or eliminated from packaged food, and if the packagingmaterials are impermeable, the food is not re-contaminated. Irradiation of packaged foodhas a particular bearing when hygiene is difficult to maintain, as is often the case, forexample, in tropical conditions.

Many studies have been conducted since the late 1940s to evaluate the nutritional valueof irradiated foods and to determine the safety of the process. The treatment process can

be designed and controlled so that the following benefits can be realized safely withoutany significant reduction in the nutritional value of the food:1. Extend shelf life of food by destroying the micro-organisms that cause spoilage;2. Make food safe to eat by destroying parasites and micro-organisms that cause

trichinosis and salmonella poisoning;3. Provide quarantine treatments for fruits and vegetables to ensure insect pests are

not transported across borders; and



http://www.cna.ca/english/nuclear_facts/applications/food_irradiation.html






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4. Prolong the shelf life of foods by slowing the ripening process and inhibiting thesprouting of root vegetables like potatoes and onions.

The good news is that more than 60 countries worldwide including the USA approved theuse of radiation and these countries have been using radiation to preserve food for overthe past five decades. In France and the Netherlands, large quantities of seafood, vegetables, fish, and frog legs are irradiated. Other countries actively involved in foodirradiation include Brazil, Mexico, Japan, Belgium and Israel. In the United States,irradiated hamburger patties are sold in every state. Papayas are irradiated in Hawaii andimported to the mainland.

In agriculture, radiation has eradicated approximately 10 species of pest insects. Foodirradiation does not make the food radioactive, and it does not change the food any more

than canning or freezing. The irradiation process exposes food to gamma rays fromcobalt-60, a radioisotope of cobalt. Sometimes, the process uses electron beams or X-raysto produce the gamma rays.

Outbreaks of food-borne diseases have been associated with all types of foods andpathogens can be transferred to foods from different sources of contamination that arisefrom product handling, processing and preparation. Food irradiation acts by damagingthe target organism’s DNA beyond its ability to repair. Microorganisms can no longer



http://www.nei.org/howitworks/foodandagriculture/




http://www.iaea.org/About/Policy/GC/GC54/GC54InfDocuments/English/gc54inf-3_en.pdf


http://en.wikipedia.org/wiki/DNA



http://en.wikipedia.org/wiki/DNA_repair











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proliferate and continue their malignant or pathogenic activities. Spoilage-causing microorganisms cannot continue their activities. Insects do not survive, or becomeincapable of reproduction. Plants cannot continue their natural ripening processes.

Following an outbreak of illness traced to contaminated salad greens, the FederalDepartment of Agriculture (FDA) in 2008 issued a final rule approving irradiation of iceberg lettuce and spinach. The purpose was to help protect consumers from infectionby such bacteria as salmonella and E. coli, the FDA said. The foods affected by the rule areloose, fresh iceberg lettuce and spinach and bagged iceberg lettuce and spinach. The FDA previously had approved irradiation of these foods to kill insects and delay spoilage.However, the doses needed for those purposes are too low to destroy most disease-causing bacteria.

Here is a partial list of approved current uses of irradiated food in the USA and Canada: United States:

o Spices;o Fruit;o Wheat/Wheat Flour;o Pork and Chicken;o Red Meats;o Shell Eggs;

http://en.wikipedia.org/wiki/Food_irradiation#cite_ref-FI_0-1













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o Pet Foods;o Food for Space Program;o Pending Approval:o Ready-to-Eat Food

Canada: o Potatoes;o Spices;o Onions;o Dehydrated Seasoning;o Wheato Flour;o Pending Approval:o

Poultry; Beef; Shrimp; Prawns; and Mangoes.

As prolonged heating is not an appropriate treatment for all foodstuffs, food irradiation isan alternative approach for food processing and treatment. One of the significant






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advantages of irradiation technology is that it destroys microorganisms withoutsignificantly increasing temperature. Irradiation can be applied to fresh vegetables, fruitsand frozen foods with no significant change to taste or texture. It can also be used to treatfoods that have been cooked conventionally and packaged ready for distribution toconsumers. Another advantage of irradiation is that it destroys spoilage causing

organisms, helping to keep meat, poultry and seafood fresh for longer.

It is worth mentioning that irradiated food cost a few cents more per pound to the cost of production. However, food prices would not necessarily rise just because a product hasbeen irradiated. In some cases, extended shelf life produces offsetting savings. A study conducted by the USDA Economic Research Service and the University of Florida foundthat consumers are willing to pay more for a safer food product.

Irradiated foods destined for the retail store have a label or a sign indicating that they have been irradiated. This includes the internationally recognized symbol called the

“radura”. Foods that contain irradiated ingredients or foods served in restaurants do nothave to be identified as being irradiated.

This chapter was published on “Inuitech – Intuitech Technologies for Sustainability” onFebruary 15, 2012: http://intuitech.biz/chapter19-nuclear-energy-applications-food-agriculture-food-quality-safety-edited-dr-mir-f-ali/

Resources:

1. Canadian Institute of Food Science and Technology:http://www.cifst.ca/default.asp?id=879

2. Food Irradiation Processing Alliance: http://www.fipa.us/q%26a.pdf 3. IAEA – Food Irradiation Makes Progress:

http://www.iaea.org/Publications/Magazines/Bulletin/Bull262/26205781721.pdf 4. IAEA – Food Irradiation in Developing Countries: A Practical Alternative:

http://www.iaea.org/Publications/Magazines/Bulletin/Bull361/36101083035.pdf 5. Consumer Acceptance and Willingness to Pay for Irradiated Products:

http://www.ilsi.org.ar/contactos/ILSI_Argentina_Comite_Bioseguridad/ 6. Canadian Nuclear Association – Why Food Irradiation:

http://www.cna.ca/english/nuclear_facts/applications/food_irradiation.html 7. Nuclear Energy Institute – Food & Agriculture:

http://www.nei.org/howitworks/foodandagriculture/ 8. IAEA Nuclear Technology Review:




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