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Irradiation Preservation of Foods

By: Nooshin Noshirvani

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Why do we preserve food?the level of food loss is high (more than 40% for fruits & vegetables and higher

for fish & meat)According to the United Nations, more

than 30 percent of the mortality rate world-wide is caused by alimentary

diseasesSome agricultural products are

important commodities in international trade. (infestation of several species of

insects and mites)The presence of parasites, some

microorganisms, yeast and moulds are also the source of problems, (toxin

formation)

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According to Statistic Canada,• the number of food-borne illnesses is estimated to be

more than:

630 000 cases/year for Salmonella,100 000 cases/year for Staphylococcus aureus,19 000 cases/year for Shigella,16 000 cases/year for Campylobacter jejuni13 000 cases/year for E. coli O157: H7. 2800 cases/year for Listeria monocytogenes,

Canada USA

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History of Food Preservation

Newest Method: Irradiation

Oldest Methods

Drying

Fermenting

Salting

Smoking

Newer Methods

freezing

Canning

Refrigeration

Preservatives

Pesticides

applied to fresh, frozen or cooked

products.physical safe environment

ally cleanefficient

technology

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What is food irradiation? (Definition)

•physical treatment that consists of exposing foods either prepackaged or in bulk to the direct action of electronic, electromagnetic rays

•When made to bombard against materials, they can knock off an electron from an atom or molecule causing ionization.

•For this reason, these are often called ionizing irradiation.

•The X- and gamma-rays are very short wavelength radiations that have very high associated energy levels.

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What are the sources of irradiation?•Gamma Rayscome from the spontaneous disintegration of radionuclides. cobalt-60 (1.17 and 1.33 MeV) : produced from cobalt-59 caesium- 137 (0.662 MeV) : a spent fuel from nuclear reactors Nuclear Waste Good penetration

•Electron BeamsStream of high-energy electrons propelled from an electron gun

(maximum energy 10 MeV).Similar to Beta ParticlesNo Waste, In-line equipment

•X-rays▫ beam of accelerated electrons is directed at a thin plate of gold

(or other metal), producing a stream of X-rays exiting from the other side (5 Mev)

▫ No Waste, In-line equipment, Good Penetration

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Characteristics of Irradiation Sources

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Gamma Rays• Cobalt-60 the choice for gamma radiation source• produced by neutron bombardment in a nuclear reactor of the

metal cobalt-59, then doubly encapsulated in stainless steel pencils to prevent any leakage during its use in an irradiator.

• Cobalt-60 has a half-life of 5.3 years, • highly penetrating and can be used to treat full boxes of fresh

or frozen food.• over 80% of the cobalt-60 available in the world market is

produced in Canada.• Other producers are the Russian, Republic of China, India and

South Africa.• Cesium 137 is the only other gamma-emitting radionuclide

suitable for industrial processing of materials. • It can be obtained by reprocessing spent, or used, nuclear fuel

elements and has a half-life of 30 years. • There is no supply of commercial quantities of cesium-137.

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Electron Beams

•Since the associated energy levels of these rays are too low to be practical value in preservation, they need to be accelerated (in cyclotrons, linear accelerators etc.) to make them acquire the required energy.

•Since electrons cannot penetrate very far into food, compared with gamma radiation or X-rays, they can be used only for treatment of thin packages of food and free flowing or falling grains.

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Action of Ionization Irradiation

Direct

• chemical events as a result of energy deposition on target molecule

indirect• radicals

formed from the radiolysis of water

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Doses of irradiation

•The international unit of measurement is the Gray (Gy).

•One Gray represents one joule of energy absorbed per kilogram of irradiated product. One Gy is equivalent to 100 rad (radiation absorbed dose)

•The desired dose is achieved by the time of exposure and by the location of the product relative to the source.

•depend upon the mass, bulk density and thickness of the food

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Units of Radiation Dose and Radioactivity

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Food Irradiation Applications

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Extent of Dose and Purpose of Food Irradiation

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Comparing to thermal pasteurization

irradiation pasteurization

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‘’cold pasteurization’’

•The maximum dose of 10 kGy recommended by the Codex General Standard for Irradiated Foods is equivalent to the heat energy required to increase the temperature of water by 2.4ºC.

• Irradiation is often referred to as a ‘’cold pasteurization’’ process as it can accomplish the same objective as thermal pasteurization of liquid foods,

•For example milk, without any substantial increase in product temperature.

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Food Irradiation: Historical Milestones• 1895 W. K. Von Roentgen discovers X-rays.• 1896 H. Becquerel discovers radioactivity.• 1896 F. Minsch suggests using ionizing radiation to kill

microorganisms in food.• 1903 M. Curie described 3 different types of radiation –

alpha, beta and gamma.• 1904 S. C. Prescott publishes effects of ionizing radiation

on bacteria.• 1905 U.S. and British patents are issued for the

proposed use of killing bacteria in food with ionizing radiation.

• 1921 B. Schwartz, a researcher at USDA, publishes studies about the lethal effect of X-rays on Trichinella spiralis in pork.

• 1950s conduct research on food irradiation.

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•1943 Preservation of ground beef by exposure to X-rays demonstrated to be feasible.

•1950 U.S. Atomic Energy Commission begins program using radioisotopes for food preservation.

•1953 U.S. Army begins food irradiation program.•1958 U.S. Federal Food, Drug and Cosmetic Act is

amended, legally defining ionizing radiation as a food additive rather than a process.

•USSR approves irradiation for potatoes and grain.•1960 Canada approves irradiation for potatoes.•1963 FDA approves irradiation for insect

disinfestation of wheat and wheat powder.•1964 FDA approves irradiation to inhibit

sprouting in potatoes.

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•1965 FDA approves irradiation to extend the shelf life of potatoes.

•1968 FDA and USDA rescind approval for irradiation of bacon granted in 1963.

•1976 Joint FAO/IAEA/WHO Expert Committee on the Wholesomeness and Safety of Food Irradiation approves several irradiated foods and recommends that food irradiation be classified as a physical process.

•1980 Joint FAO/IAEA/WHO Expert Committee concludes that any food irradiated up to a maximum overall average dose of 10kGy presents no toxicological hazard and requires no further testing.

•1983 FDA and Canada approve irradiation for insect disinfestation in spices and dry vegetable seasoning (38 commodities).

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•1985 FDA approves irradiation to control Trichinella spiralis in pork and to disinfest dry enzyme preparations.

•1986 FDA approves irradiation to delay ripening (maturation) of some fruits and vegetables, and to decontaminate dry or dehydrated enzyme preparations.

•1990 FDA approves irradiation to control pathogens such as Salmonella in fresh and frozen poultry.

•1997(FDA) and 1999 (USDA) Approval of irradiation to control pathogens in fresh and frozen red meats (beef, lamb and pork).

Which foods are irradiated? • Wheat flour – control of mold

• White potatoes – inhibit sprouting

• Pork – kill Trichinia parasites

• Fruit and Vegetables – insect control; increase shelf life

• Herbs and Spices - sterilization

• Poultry – bacterial pathogen reduction

• Meat – bacterial pathogen reduction

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What changes occur in the quality of irradiated foods?

• Irradiation is a “cold” process, and therefore…▫Little if any change in physical appearance No textural or color changes as with traditional heat preservation

•Possible chemical changes▫Off-flavors ▫Tissue softening

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Scope of Irradiation

Disinfestation

Shelf Life Extension

Decontamination

Product Quality Improvement

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Irradiation is an effective alternative to fumigation for insect control

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Disinfestation (control of insects)• Commercial processing of irradiated potatoes has been

carried out in Japan since 1973.• important postharvest treatments• A low dose of 0.15–0.50 kGy can damage insects at

various stages of development that might be present• Irradiation can damage insect’s sexual viability or its

capability of becoming an adult• Radiation disinfestation can facilitate trade in fresh

fruits, such as citrus, mangoes, and papayas which often harbour insect pests of quarantine importance (0.2-0.7 KGy)

• a combination treatment of low doses of gamma irradiation (0.35 kGy). and heat would be advantageous to cause complete killing of insects in dates

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Comparing irradiation & fumigants

methyl bromide & phosphine irradiation

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Shelf Life Extension

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Shelf Life Extension

•A very low radiation dose of 0.15 kGy or less (0.02–0.15), inhibits sprouting of products such as potatoes, yams, onions, garlic, ginger, and chestnuts.

•Yang et al found that the treatment of garlic bulbs with 0.15 kGy can inhibit sprouting and reduce weight losses during storage

•The irradiation affects the flavor compounds of garlic.

•delay the ripening and senescence of some tropical fruits such as bananas, litchis, avocados, papayas, and mangoes at 0.12–0.75 kGy

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Shelf Life Extension

•Delay Microbial development in fruits•Extends the shelf life of perishable products such as beef,

poultry, and seafood by decontamination of spoilage microorganisms.

•The shelf-life of many fruits and vegetables, meat, poultry, fish and seafood can be considerably prolonged by treatment with combinations of low-dose irradiation and refrigeration that do not alter flavour or texture.

•Pseudomonas spp., are relatively sensitive to irradiation. (dose of 2.5 kGy) applied to fresh poultry carcasses enough to eliminate Salmonella, and will also kill many, but not all, spoilage bacteria.

• This will double meat shelf-life, provided it is kept below 5°C

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Decontamination

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Reduction of pathogenic microorganisms

• known as ‘’trichina-safe’’• 0.3 Kgy for trichina & 0.5 (Toxoplasma gondii)

Destroy parasites

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Reduction of pathogenic microorganisms• Irradiation is currently the only known method to inactivate

these pathogens in raw and frozen food.

• Escherichia coli O157:H7, Salmonella, Campylobacter jejuni, Listeria monocytogenes, and Vibrio

• Salmonella and C. jejuni are usually associated with poultry( 2.5 kGy )

• E. coli O157:H7 has also been linked to meat and dairy products in the United Kingdom, hamburger meat, apple juice and water in the USA, and vegetables in Japan

• Listeria monocytogenes has been associated with dairy products, processed meats and other foods having a relatively long shelf-life under refrigeration.

• Vibrio sppconsumption of raw mollusks.

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•sensitivity of Pathogens to low levels of ionising radiation

•As the irradiation dose increases more microorganisms are affected but a higher dose, introduce changes in sensory qualities and a balance must be attained between the optimum dose required

•Eggs and egg products are often contaminated with Salmonella

•Frozen egg and dried egg could be irradiated at doses of up to 2- 5 kGy without quality loss and that this dose provided sufficient hygienic protection.

•Seafood (shellfish & frozen shrimp) is often contaminated with pathogenic organisms such as Salmonella, Vibrio parahaemolyticus, and Shigella, Aeromonas hydrophila. dose of about 3 kGy

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Irradiation sterilized products

•astronauts in the NASA space shuttle programme

• their superior quality, •safety •variety, •Limited commercial-scale sterilization of

various ready-to-eat foods by high dose irradiation has been carried out in South Africa during the past 10 years to serve military personnel and campers, yachters and hikers.

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Product Quality Improvement

Increase shelf life and microbiological properties

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Advantages of IrradiationMinimize Food Losses

Improve Public Health

Increase International Trade

An Alternative to Fumigation of Food

Increase Energy Saving

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Minimize Food Losses

•Especially in the Third World, irradiation has high potential where in many cases food is spoiled during postharvest stage

Disinfestation

sprout inhibit

ion

delayed ripenin

g

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Improve Public Health

•Reduction of:

pathogenic microorganisms parasites

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Increase International Trade

(i) infestation by insects

(ii) infection by

microorganisms

(iii) their limited shelf

life

restricts long-distance shipments.

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An Alternative to Fumigation of Food

toxic nature and environmental impact

effect

ethylene

oxide

methyl

bromide

ethylene

dibromide

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Increase Energy Saving

Canning

20,180 kJ/kg

Refrigeration

17,760 kJ/kg

frozen storage

46,600 kJ/kg

refrigerated &

irradiated

17,860 kJ/kg

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Effects on Microorganisms and Food Components

•affects microorganisms, such as bacteria, yeasts, and molds

•causing lesions in the genetic material of the cell, effectively preventing it from carrying out the biological processes necessary for its continued existence

•The principal targets of irradiation are nucleic acids and membrane lipids

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Effects on Microorganisms

Mode of Action

nucleic acids

prevention of replication

cell reproduction impossible

membrane lipids

functions, such as permeability

membrane enzymes

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susceptibility of microorganisms to irradiationMain factor of susceptibility

atmosphere

Presence of oxygen

Absence of oxygen

temperature

Dose level Medium

Type of organis

m

Size

Cell wall (Gram positive of negative)

Number and age of cells

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Type of microorganism•As a rule, the simpler the life form, the

more resistant it is to the effects of irradiation.

Parasites and insect pests

• have large amounts of DNA

Humans

Molds

Bacteria

viruses

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Effect of Irradiation on Foodborne Parasites

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Comparison of radiation sensitivity of different organisms

1 10 102 103 104 105 106 107

NO ACUTE EFFECTS

LETHAL TO

HUMANS

SPROUTING INHIBITED

LETHAL TO INSECTS

STERILIZATION OF MICROORGANISMS

Dose(rad)

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Effects of Irradiation on Food Components

Effects of

Irradiation

Proteins

Carbohydrates

Lipids

Vitamins

Enzymes

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Effect on Proteinspeptide linkages

• not attacked

sulfur linkages

• attacked

Low doses : may cause molecular uncoiling, coagulation, unfolding, and even molecular cleavage and splitting of amino acidsAt 10 kGy radiation, overall increase in total free amino acids was observed mainly due to the rise in the levels of glycine, valine, methionine, lysine, isoleucine, leucine, tyrosine, and phenylalanineaffects the functional properties of proteinsEggloss of viscosity in the whiteoff-flavors in the yolkMilkoff-flavorsincrease in rennet coagulation time reduced heat stability

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Effects on Carbohydrates

•break high-molecular-weight carbohydrates into smaller units

•softening of fruits and vegetables through breakdown of cell wall materials, such as pectin

•Sugars may be hydrolyzed or oxidized• irradiation of wheat at 0.2–10 kGy increase in

initial total reducing sugars and generation of bread flavor and aroma

• Irradiation of pure carbohydrates produced degradation products, which have mutagenic and cytotoxic effects.

• However, these undesirable effects were produced using very high dose of irradiation

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Effect on Lipids

• initiates the normal process of autoxidation of fats which gives rise to rancid off-flavors

•The formation of peroxides and volatile compounds, and the development of rancidity and off-flavors

•This process can be slowed by the elimination of oxygen by vacuum or modified atmosphere

•The peroxide formed can also affect certain labile vitamins, such as vitamins E and K

•The lipids in cereals degraded only at high doses of irradiation and no significant effects on iodine value, acidity, or color intensity of wheat flour lipids were observed

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Effect on Vitamins•The extent of vitamin C, E, and K destruction

depends on the dosage used,• thiamine is very labile to irradiation.•The losses are low with low dose•Ascorbic acid in solution is quite labile to

irradiation but in fruits and vegetables seems quite stable at low doses of treatment

•Vitamins (antioxidant activity), such as A, B12, C, E, K, and thiamine, are degraded when irradiation is carried out in the presence of oxygen

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Effects on Enzymes

•Enzymes in foods must be inactivated prior to irradiation because it is much more resistant to radiation than microorganisms

•complete inactivation of enzymes requires about 5–10 times the dose required for the destruction of microorganisms

•The D values of enzyme can be 50 kGy and almost four D values would be required for complete destruction

• irradiated foods will be unstable during storage due to their susceptibility to enzymatic attack than nonirradiated foods

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Applications of Irradiation in Foods

•Fruits and Vegetables (Berries, Mangoes, Carrots, Papaya, Strawberries)

•Spices•Cereals and Grains•Animal Foods (Poultry, Mutton, Beef,

Pork, Processed Meats, Fish and Fish Products)

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Plant Foods

promising technology to maintain the quality of fresh fruits and vegetables because

• it has the potential to control both spoilage and pathogenic microbes• physical means for pasteurization without changing the fresh state• at a pasteurization dose (2–5 kGy) could control post-harvest spoilage and

diseases

• undesirable symptoms are• tissue softening partial depolymerization of cell wall polysaccharides, mainly cellulose and

pectins damage to cell membrane• enzymatic browning

Fungal diseases

pathological

breakdown

insect infestatio

n.

tissue damage this technology

should be used in combination withother treatments.

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• irradiation with heat strong inactivation effect (1% survival) was obtained when irradiation plus heat (1.25 kGy 46°C, 5 min)

• Papaya: 48.9°C for 20 min in combination delayed ripening with optimum dose of 0.75 kGy

• heating and irradiation had a stronger interaction than heating and chilling

• The oxidation can be minimized by irradiating in an atmosphere with reduced oxygen content,

• low-dose irradiation combined with modified atmosphere is increasingly considered for control of microorganisms and delayed ripening

• Couture and Willemot showed the synergistic action of irradiation combined with high carbon dioxide for control of mold development on strawberries. (7% oxygen and 20% carbon dioxide and 1 kGy)

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Response of 23 Fruits to Irradiation

Strawberry 1.5–

2kGy (3 kGy) 14 days.

Papaya & mango (0.25 -1

kGy)

Mushroom (2 - 3kGy) two-fold

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•Not all fruits and vegetables are suitable for irradiation because undesirable changes in colour or texture, or both, limit their acceptability.

•different varieties of the same fruit or vegetable may respond differently to irradiation.

•The time of harvest and the physiological state also affects the response of fruits and vegetables to irradiation

•For delaying ripening in fruits it is important to irradiate them before ripening starts.

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Shelf-life of strawberries can be

extended by irradiation!!!

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• Spices, herbs and vegetable seasonings are valued for their distinctive flavours, colours and aromas.

• they are often heavily contaminated with microorganisms because of the environmental and processing conditions under which they are produced (open air drying procedures)

• Before use in food the microbial load should be reduced.• Because heat treatment can cause significant loss of flavour

and aroma, a ‘’cold process’’, such as irradiation, is ideal.• Until recently, most spices and herbs were fumigated,

usually with sterilizing gases such as ethylene oxide to destroy contaminating microorganisms

• the use of ethylene oxide was prohibited by an European Union (EU) directive in 1991 and has been banned in a number of other countries because it is a carcinogen.

Spices

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Spices

• increasingly important use of irradiation for decontamination of spices

•A dose of 2.5 kGy reduced the fungal and bacterial load by 2 log cycles, and 7.5 kGy eliminated the fungal population of ground or whole pepper.

Clostridium Staphylococcus Bacillus Aspergillus Fusarium

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• Irradiation of spices on a commercial scale is practised in over 20 countries and global production has increased significantly from about 5,000 tonnes in 1990 to over 60,000 tonnes in 1997.

• In the USA alone over 30,000 tonnes of spices, herbs and dry ingredients were irradiated in 1997 as compared to 4,500 tonnes in 1993.

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Cereals and Grains

•with low doses of irradiation to eliminate fungi, since some of these organisms can produce mycotoxins

•0.2–1.0 kGy are effective in controlling insect infestation in cereals

• Increasing the dose to 5 kGy totally kills the spores of many fungi, which survive lower doses

• loaf volume and baking quality deteriorated above 5 kGy irradiation irrespective of the baking formula.

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Animal foods•The irradiation is effective in preventing or delaying

the microbial spoilage of fresh meats and poultry.•Early studies indicated that irradiation at doses

between 0.25 and 1kGy under aerobic conditions increased microbiological shelf life, but accelerated rancidity

• In case of meats, doses up to 2.5 kGy control Salmonella, Campylobacter, Listeria monocytogenes, Streptococcus faecalis, Staphylococus aureus, and Escherichia coli in poultry and other meats.

• The doses in excess of 2.5 kGy may change flavor, odor, and color, but these changes can be minimized by irradiating at low temperature or in absence of oxygen

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Threshold Dose for an Identifiable Irradiated Flavor for Meats

oxidation of pigment to yield brown or gray discolorations by o2

drip loss from the cut surface of lean,

oxidation of meat lipids that causes off-flavors by atmospheric

irradiation coupled with vacuum packaging has the

potential to extend the shelf life

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Poultry

•dose of 2.5–5kGy dose since this can extend shelf life at chill temperatures from 6 to 14 days without insignificant organoleptic quality change

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Combination irradiation with natural antimicrobial (rosemary & thyme)

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Processed meat

•The amount of nitrite required in cured meats possibly can be reduced by irradiation, thus the chance of nitrosamine formation can be lowered

•can be reduced from normal levels of 120–150 to 20–40 mg/kg without loss of organoleptic quality

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Nham (fermented pork sausage) is commercially irradiated

and marketed in Thailand.

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Fish and fish products

•control of pathogenic organisms and the extension of shelf life of fresh fish could be achieved with relatively low doses 2.5 kGy

•Clostridium botulinum (A, B, E, and F) present in fish and fish products remained unaffected by the low doses of irradiation.

•Thus, precautions during storage under 3°C and oxygen availability to the product need to be taken

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Combined effect of low dose gamma (3KGy) and antimicrobial coating

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Nutritional Quality of Irradiated Foods

•As irradiation is a cold process does not substantially raise the temperature of the food being processed,

•nutrient losses are small and often significantly less than losses associated with other methods of preservation such as canning, drying and heat pasteurization.

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Radiolytic products formed in irradiated foods are similar to products formed by cooking

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problem in the irradiation of foods in plastic containers

• Production of gas and volatiles compounds, which may migrate into the food and cause off-flavors.

• At sterilizing doses, nylon gives rise to little off-odor production,

• in case of polyethylene, short fragmentations of the polymer are produced, which enter the food

• Volatile compounds are formed in polyethylene, polyester terephthalate, and oriented polypropylene after irradiation dose from 5 to 50kGy.

• Twenty-two compounds (polyester terephthalate), 40 (oriented polypropylene), and only acetone was identified for polyethylene, which could be a good candidate for irradiation of packaged food products.

• These compounds are hydrocarbons, ketones, and aromatic compounds

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Packaging of Irradiated Foods

The properties of polyethylene terephthalate (PET) are well preserved during irradiationAt doses of 60 kGy and higher, some damage may occur in tin-coated steel and aluminum containers, but at the level of sterilizing doses there should not be any affectAt doses less than 20kGy, physical changes in flexible containers are negligible.High doses above 30 kGy cause brittleness in cellophanes, saran, and plioform, while 20 kGy or more can cause inconsequential physical changes in mylar, polyethane, vinyl, and polyethylene plastic filmsAt strong doses of 50kGy, mechanical properties of polymers can be improved by cross-linking

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Packaging Materials Approved by FDA for Use during Irradiation of Food

Packaging Materials

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The common features of all commercialirradiation facilities are

• the irradiation room •A system to transport the food into and

out of the room•concrete shielding (1.5 - 1.8 metres thick)

surrounding the irradiation room, which ensures that ionising radiation does not escape to the outside of the room.

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• In the case of a gamma irradiator, the radionuclide source continuously emits radiation and when not being used to treat food must be stored in a water pool (usually 6 metres in depth).

• Known as one of the best shields against radiation energy, water absorbs the radiation energy and protects workers from exposure if they must enter the room.

• In contrast to gamma irradiators, machines producing high-energy electrons operate on electricity and can be switched off.

• The transport system : conveyor or a rail system• In a gamma irradiator, the size of the containers in which

the food is moved through the irradiation chamber can vary and pallets up to 1 m3 may be used

• with machines, the bulk or thickness of a product which can be treated is much less and hence there is a fundamental design difference between the two types of irradiator.

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Gamma Irradiator for food processing

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Electron beam irradiator for food processing

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World-wide Utilization of Food Irradiation

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Food irradiation items in the world in 2005

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Quantity of irradiated foods in the world

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Quantity of food irradiation in the world in 2005

Vietnam

Ukraine

Isreal

China

China

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• In 1980, it concluded that the irradiation of any food commodity up to an overall average dose of 10 kGy presents no toxicological hazard and requires no further testing.

• in 1983, of a worldwide standard covering irradiated foods.

• The standard was adopted by the ,(FAO) and (WHO), more than 150 governments.

• The Codex General Standard for food irradiation was based on the findings of a Joint Expert Committee on Food Irradiation (JECFI) convened by the FAO, WHO, and the International Atomic Energy Agency (IAEA)

• As of August 1999, over 30 countries are irradiating food for commercial purposes.

• Today, health and safety authorities in over 40 countries have approved irradiation of over 60 different foods, ranging from spices to grains to deboned chicken meat, to beef, to fruits and vegetables

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• In September 1997 a Study Group was jointly convened by the WHO, FAO and IAEA to evaluate the wholesomeness of food irradiated with doses above 10 kGy.

•This Study Group concluded that there is no scientific basis for limiting absorbed doses to the upper level of 10 kGy as currently recommended by the Codex Alimentarius Commission.

•Food irradiation technology is safe to such a degree that as long as the sensory qualities of food are retained and harmful microorganisms are destroyed, the actual amount of ionizing radiation applied is of secondary consideration.

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Why are countries interested?

Interest in the irradiation process is increasing because of:

•persistently high food losses from infestation, contamination, spoilage;

•Prohibition on the use of a number of chemical fumigants for insect and microbial control in food,

•Effective alternative to protect food against insect damage and as a quarantine treatment of fresh produce.

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Estimated quantities of irradiated spices and dried vegetable seasonings

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How much food is being commerciallyirradiated?

•a few hundred thousand tonnes of food products and ingredients are irradiated worldwide.

•This amount is small in comparison to the total volumes of processed foods and not many of these irradiated food products enter international commerce.

•Adopting public understanding and acceptance of the process.

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Technological Problems and Limitations of Irradiation

•Major Problems of Irradiation•Legal Aspects and Safety Issues•Consumers’ Attitude

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Major Problems of Irradiation

•has a low operating cost• requires low energy

But: high capital costs requires a critical minimum capacitythreshold doses above which organoleptic

changes and off-flavor development occur at low doses all microorganisms and their toxins will not be eliminated.

Limitation in packaging material

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Legal Aspects and Safety Issues•A joint FAO/IAEA/WHO Expert Committee

on Food Irradiation (IJECFI) concluded that irradiation of food up to an overall average dose of 10 kGy causes no toxicological hazards and introduces no special nutritional or microbiological problems

• Irradiation of food and agricultural products is currently allowed in about 40 countries and approximately 60 commercial irradiation facilities are operating in the United States

•The most common irradiated food products for commercial use are spices and dry vegetable seasonings

• recent ban on the use of ethylene oxide for food by European Union could increase the quantity of spices and vegetables seasonings processed by irradiation in the near future

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Foods permitted to be irradiated under FDA’s regulations

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International recognized logo for irradiated foods.

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Consumers’ Attitude

•consumer education• in advanced countries consumers at large

are still not knowledgeable about food irradiation.

•accurate information about safety, benefits, and limitations of food irradiation

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Some questions about irradiation technique???

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Can irradiation be used to make spoiled food good or to clean up dirty food?

•NO. Neither irradiation nor any other food treatment can reverse the spoilage process and make bad food good

•While irradiation can reduce or eliminate spoilage bacteria or pathogenic microorganisms which may be present in a spoiled food, it cannot improve its sensory properties , the bad appearance, taste or smell will remain

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Do workers at irradiation facilities face dangers from long-term or accidental

exposure to radiation?

•all exposures of workers to radiation are prevented because the radiation source is shielded.

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Have there been any major accidents at industrial irradiation facilities?

•Over the past 30 years, there have been a few major accidents at industrial irradiation facilities that caused injury or death to workers because of accidental exposure to a lethal dose of radiation.

• All of the accidents happened because safety systems had been deliberately bypassed and proper control procedures had not been followed.

•None of these accidents endangered public health and environmental safety.

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Do the free radicals which are producedduring irradiation affect the safety of the

food?• NO.

• free radicals are also formed by other food treatments, such as toasting of bread, frying, and freeze drying, and during normal oxidation processes in food.

• They are generally very reactive, unstable structures, that continuously react with substances to form stable products.

• Free radicals disappear by reacting with each other in the presence of liquids, such as saliva in the mouth.

• Consequently, their ingestion does not create any toxicological or other

• harmful effects.

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Can irradiated food become toxic?•NO. •Energies from these radiation sources are

too low to induce radioactivity in any material, including food.

• If the acquired energy is too high, induced radioactivity in foods could occur upon irradiation

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Does the irradiation process make foodradioactive?

•NO. • Irradiation does not make food

radioactive. Everything in our environment, including food, contains trace amounts of radioactivity.

•This means that this trace amount (about 150 to 200 becquerels/kg) of natural radioactivity from elements such as potassium is unavoidable in our daily diets.

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مروری بر کاربرد پرتودهی در ایران و انرژیQ اتمی در ایرانکاربردهای صلح آمیز

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که مقدمات ایجاد آن از اوایل سال سازمان انرژی اتمی ایران• فراهم گردیده بود، با تصویب قانون »سازمان انرژی اتمی« در ۱۳۵۳. عمال به صورت یک شخصیت حقوقی رسمیت یافت ۱۳۵۳/۴/۱۶تاریخ

صنایع غذایی، دامپزشکی، و دامپروری •در حوزه صنایع غذایی تبدیلی کشاورزی نیز برای استریل کردن •

)می توان قارچها و باکتریها ، ویروسها میکروبهامحصوالت (از بین بردن از کاربردهای مختلف انرژی هسته ای بهره برد.

تکنیک های هسته ای در حوزه دامپزشکی موارد مصرفی چون تشخیص و •درمان بیماری های دامی، تولید مثل دام، تغذیه دام، اصالح نژاد، بهداشت

و ایمن سازی محصوالت دامی و خوراک دام دارد.تشعشعات هسته ای کاربردهای زیادی در کشاورزی دارد که مهم ترین •

آنها عبارتست از:موتاسیون هسته ای ژن ها در کشاورزی•کنترل حشرات با تشعشعات هسته ای•جلوگیری از جوانه زدن سیب زمینی با اشعه گاما•انبار کردن میوه ها•

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سازمان انرژی اتمی ایران

مرکز کرج مرکز یزد

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استفاده • ی شیمیای مواد از محص¨والت ر عم ش افزای برای کشاورزی در به بعد تمام محصوالت صادراتی باید با استفاده 2015می شود و از سال

از پرتوها استریل شوند.

کاربردهای • در نیز کشاورزی محص¨والت نگهداری عم¨ر ش افزای مس¨ئله مثال عنوان ه ب و می گیرد جای هس¨ته ای ی خرمای 131انرژ تن هزار

تولیدی فارس به همین دلیل در نگهداری و بازار رسانی دچار مشکل است.

این استان را بدون استفاده از • از پرتودهی می توانیم خرمای استفاده ا بمحصوالت شیمیایی از پاتوژن ها عاری نماییم.

از صادرات غیرنفتی ایران را به خود اختصاص داده است، درصد 11پسته • درصد پسته ایران به این سم آلوده 10درگیر آفالتوکسین شده و ساالنه

می شود ولی با استفاده از روش پرتودهی گاما می توان این مشکل را حل کرد.

دفع آفات گندم و سایر دانه ها •

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معرفی مرکز پرتو فرآیند یزدی • ی اتم ه س¨ازمان انرژ د یزد وابس¨ته ب و فرآین ز پرت  مرک

با هدف تحقیقات و کاربرد پرتوهای 1376ایران در سال د ف تولی الکترون و ایک¨س ک¨ه در شتاب دهنده های مختل

¨ر ¨د در کیلومت ¨ت در اس¨تان یزد 15میشون جاده یزد - تفرسما شروع بکار کرد.

ال • ه اول س شتاب دهنده الکترون پرقدرت 1377 در نیماین مرکز پرتودهی آزمایشی خود را آغاز نمود.

پ¨س از ط¨ی دوره آزمایش¨ی ای¨ن شتاب دهنده از اوای¨ل •ال نایع و 1378س ه ص ی ب ه خدمات پرتوده ت ارائ در جه

ه ی و کاربردی متعدد بکار گرفت ه های تحقیقات انجام پروژاست.شده

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واحد پرتودهی

یزد

بخش پرتو فرآیند

بخش آزمایشگا

ه و کنترل کیفی

بخش محصوال

ت انقباض حرارتی

بخش پشتیبان

ی

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:  مشخصات عمده شتاب دهنده مرکز یزد

¨د یزد از نوع • ¨و فرآین ¨ز پرت شتاب دهنده الکترون مرکا چهار ن شتاب دهنده های ب ن و پرقدرت تری د تری جدی

) موجود در جهان Rhodotronخروج¨¨¨¨¨¨¨¨ی عمودی (اس¨ت. ای¨ن شتاب دهنده از نوع رودوترون و افق¨ی و

میلیون الکترون ولت میباشد.10 و 5انرژيهای ن دستگاه • ی ای ا دو 100قدرت نهای کیلووات است و ت

برابر قابل افزایش میباشد و میتواند پرتوهای ایکس و الکترون تولید نماید.

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درحال حاضر توان شتاب دهنده مرکز پرتو فرآیند یزد • مگا الکترون 10 کیلووات و انرژی آن حداکثر 100

ولت میباشد که باالترین انرژی مجاز شتاب دهنده صنعتی است ، بعبارت دیگر با این سیستم میتوان در

محصوالتی مانند مترمکعب 10هر ساعت حدود لوازم پزشکی را استریل نمود.

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 مرکز پرتو فرآیند یزد با تجهیزات و امکانات خاص خود در زمینه های زیر آماده ارائه

خدمات میباشد :

. پرتودهی مواد پلیمری:               1. پرتودهی محصوالت پزشکی یکبار مصرف  :2. پرتودهی مواد غذایی :3. کنترل کیفی مواد پلیمری :4. میکروبیولوژی :5. انجام پروژه های تحقیقاتی :6. دزیمتری7

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بیشترین کاربرد

محصوالت غذایی مورد تیمار: محصوالت خشکشامل حبوبات، ادویه ها و سبزیجات

،محصوالت غیر غذایی: وسایل بهداشتی، پودر بچهوسایل استریل جراحی، نخ های بخیه

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طرح های تحقیقاتی مرکز کرجخرما: کاهش بار میکروبی و آفات•انار : مقابله با آفت گلوگاه انار•سیب: مقابله با کپک پنی سلیوم•میگو: کنترل ویبریو• گل های زینتی: از بین بردن آفات و شته، رنگ و شمایل متفاوت •تولید آنزیمهای گلوکاناز، پکتیناز از قارچها•افزایش تولید اسید گلوتامیک از کرنی باکتریوم گلوتامیکوم•تولید اسید آمینه لیزین : کاربرد در مواد غذایی و دامی•گیاهان دارویی: تولید ترکیبات معطر جدید•تولید ارقام جدید حاصل از پرتودهی با استفاده از جهش و موتاسیون محصوالت •

کشاورزی یکی از مباحثی بوده که برای اجرای آن بستر الزم توسط محققان مرکز تحقیقات جهاد کشاورزی فراهم شده است.

افزایش توان تولید آستاگزانتین توسط مخمر فافیا که در درمان آب مروارید، آب سیاه •و سرطان پستان نقش دارد

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پروژه های معرفی به صنعت

2 س

ال پروژه

ارزیابی

یافتن دز مناسب

بهینه سازی

بررسی مشکالت رادی

کال های آزاد

ارزیاب

ی حسی

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مشکالت پرتودهی

احتمال کاهش رنگ میوه ها و سبزی ها ؛ کاهش رنگ •قرمز انار و اثر آنتی اکسیدانی آن

ایجاد موتانتهای جدید باکتری و غیر قابل شناسایی •بودن آنها

کامل نبودن زیر ساخت ها، •کاهش چشمه رادیوایزوتوپ ها و طوالنی شدن مدت •

زمان پرتودهیکمبود منابع مالی و تحریم های پیش رو از جمله •

(تکمیل مرکز پرتودهی گامای چالش های این فناوری میلیارد ریال اعتبارنیاز دارد)110خاورمیانه

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پروژه های در حال ساختسامانه پرتودهی چند منظوره گاما در شهرکرد در •

حال ساختساخت پرتودهی گاما در شیراز•پیشنهاد سازمان انرژی اتمی مبنی بر ساخت سامانه •

پرتودهی در بناب

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استانداردهای ملی محصوالت پرتودهی شده

بیشترین کاربرد در ایران:•استرلیزاسیون سرد ادویه ها دفع آفات حبوبات

3102 آئين كار پرتودهي ادويه•تجهيزات پرتودهي مواد غذايي – آئين كار كاربرد •

8033

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مقادیر توصیه شده برای دز پرتو در 8033استاندارد

کیلوگری7ماکیان: • کیلوگری1حبوبات: •ادویه ها و چاشنی ها:• :کیلوگری1 کنترل آفت :کیلوگری10کاهش بار میکروبی کیلوگری3توت فرنگی: • کیلوگری2/2شیالت: • کیلوگری1گندم: • کیلوگری1سیب زمینی و پیاز: • کیلوگری1خرما: •

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Are irradiated foods safe?

YES!Radiation doses are never large

enough to cause nuclear changes that would cause the food material to

become radioactive.

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So, now would you eat an irradiated food product?

WhyOr

Why not?

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