Complete information about food irridiation.

1. Food Irradiation 1

2. Food Irradiation
•Definition-
•Radiation: The emission and propagation
of energy through matter or space by
electromagnetic disturbances called
photons.
•Irradiation: the process of applying
radiation to matter.
•Food irradiation: application of
irradiation as ionizing energy to foods. 2

3. Why irradiate food-
1.Prevention of foodborne
•illness effectively eliminates microbes; Salmonella
and E. Coli
2.Preservation
•Destroy/ inactivate organisms that cause spoilage
and decomposition.
3.Control of insects
•Destroys insects e.g imported fruits.
4.Delay of sprouting and ripening
•Lengthen the longevity of products e.g: potatoes.
5.Sterilization
•Useful for patients in the hospital especially with
impaired immunity. 3

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5. Sources of radiation used in food irradiation-
1.Gamma Rays are emitted from radioactive forms of
the element cobalt (Co60) or of the element cesium
(Cs137). Gamma radiation is used routinely to sterilize
medical, dental and household products and is also used
for the treatment of cancer.
2.X-rays are produced by reflecting a high energy stream
of electrons off a target substance (usually one of the
heavy metals) into food. X-rays are also widely used in
medicine and industry to produce images of internal
structures.
3.Electron beam (or e-beam) is similar to x-rays and is a
stream of high-energy electrons propelled from an
electron accelerator into food. 5

6. Gamma irradiation X-ray Irradiation
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8. Dose and dose rate -
•Ionizing energy processes create enough of an
absorbed dose to destroy microbes.
•Unit of absorbed dose in food is kGy (kilograys).
•Dose can be divided into three categories:
1.Radicidation
2.Radurization
3.Raddapperization
Dose and dose rate-
•“Low” (Radicidation) Controls insects in grains
and fruits
•Inhibit sprouting in tubers
•Delay the ripening of some fruits/vegetables
•Reduce the problems of parasites in products of
animal origin. (e.g: Trichinella spiralis in pork)
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9. Dose and dose rate-
“Medium” dose (1~10 kGy) (Radurization)
•Control Salmonella, Shigella, Campylobacter,
Yersinia, Listeria and E.coli in meat poultry and
fish.
•Delay mold growth on strawberries and other
fruits “High” dose (>than 10kGy)
(Radapperization)
• Kill microorganisms and insects in spices
• Commercially sterilize foods, destroying all
microorganisms of public health concern (i.e,
special diets for people with weakened immune
systems) 9

10. Does the food become radioactive?
•To make the food become radioactive, it
will require a lot of energy; 15MeV.
•Foods are actually naturally radioactive.
•Due to natural presence of Ca, P, K, and
S elements in the food.
•Fresh foods vs irradiated foods?
•The longer the storage time of irradiated
food, more natural radioisotopes have
time to undergo decay.
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11. Effects of irradiation on microorganisms -
•Indirect effects-
Due to formation of the free radicals during
radiolysis of water molecules. Free radicals
are highly reactive - form stable products.
Combine with one another or oxygen
molecules – oxidizing agents. Can damage
bacterial cell components. Unstable free
radicals react with bacterial cell membranes
to change or damage their structure-
bacterial death.
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12. •Direct effects-
Ionizing radiation kills microbes by
damaging biomolecules of their cells.
Incoming photon hit electrons in the atoms
of microbes or food molecules. During the
collision, photon’s energy is transferred to
the electron changing the photon’s
direction. Electron free to collide with
neighboring electron. This cause chemical
bonds breakage interrupts normal cell
metabolism and division.
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14. Effect of food irradiation on food quality-
•The food molecules are made of water, lipids,
proteins, carbohydrates and vitamins.
•Radiation energy generates a degradative
reaction when it interacts with food →
radiolysis.
•Products of radiolysis is known as radiolytic
products.
•Irradiation cause changes to food molecules
particularly at high doses.
•Sterilization levels causes nutrient loss and
desirables effects.
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15. How does irradiation effect food quality?
•Food water
•Radiolysis of water molecules produce hydroxyl
radicals.
•Highly reactive species that can cause
characteristics associated with food spoilage e.g:
off-flavour and off-odors.
•To minimize this effects:
•Apply lowest effective irradiation dose
•Irradiate at lower temperature
•Choose appropriate packaging in terms of
moisture and oxygen barrier properties.
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16. How does irradiation effect food quality?
•Food Lipids
•Absence of oxygen leads to cleavage of interatomic
bonds
•Producing compounds e.g. CO2, alkanes, alkenes and
aldehydes
•Presence of oxygen, lipids are highly vulnerable to
oxidation by free radicals, a process that yields
peroxide, carbonyl compounds and alcohols
•Rancidity – high unsaturated fatty acid
•To minimize effects:
•Vacuum packaged and low temperature used during
irradiation
•Adding lipid-soluble antioxidants and use lowest
irradiation dose 16

17. How does irradiation effect food quality? •Food
proteins
•Proteins are not significantly degraded at
low doses of irradiation.
•Does not inactivate enzymes involved in
food deterioration.
•Most enzymes survives higher doses
•Biological value of protein remain high
•Availability of essential amino acids is not
compromised.
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18. How does irradiation effect food quality?
•Food Carbohydrates
•Large CHO molecules (polysaccharides)
are broken down by irradiation.
•Depolymerization reduces gelling and
functional properties such as starches and
gums
•Protection by other food constituents
•Effect on simple sugar is negligible.
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19. How does irradiation effect food
quality?
•Food vitamins
•Have varying degrees on sensitivity
•Some shows sensitivity at higher
dose, e.g: Vitamin A, C, E and B1
•Sensitivity is apparent in food
packaged under air.
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20. Does radiation create unique radiolytic products
-
•Radiolytic products are unstable atoms or
molecules derived from substances naturally
present in foods treated by ionizing energy.
•A free radical is one such type of radiolytic
products.
•Formed as result of irradiation, might cause
cancer.
•Radiolytic products produced from radiation
is just the same as other radiolytic products
from conventional processing methods.
•Concentration is much more lower. 20

21. Regulation of Irradiated food -
•Considered as a food additive by the FDA
•For approval for any irradiated food, FDA
requires the foods labeled with statement:
•Treated by ionizing energy/treated by
irradiation
•International symbol of irradiation, Radura
•Labeling requirement apply only to foods
sold in stores
•No labeling requirement if minor ingredients
in other foods and restaurant foods.
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22. Foods have been approved for irradiation- •FDA
has approved a variety of foods for irradiation
in USA including:
•Beef and pork.
•Poultry
•Mollusk shellfish
•Shell eggs
•Fresh fruits and vegetables.
•Lettuce and spinach
•Spices and seasonings.
•Seeds for sprouting
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23. Conclusion-
•Consumer are gaining knowledge about
the benefits of food irradiation and its
potential to reduce the risk of foodborne
disease but the process is not a
replacement for proper food handling
practices.
•Irradiation like other prevention
methods, however measures have to be
taken to prevent foodborne illness.
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25. https://www.slideshare.net/razifshahril/food-irradiation-41131374
Ref-
https://en.wikipedia.org/wiki/Food_irradiation
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