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Food Toxicology
Learning Objectives
Define food irradiation.
Explore the background of ionizing radiation and its
application to food.
Food Irradiation Describe the various food irradiation processes.
List the benefits of food irradiation.
List the food safety, food quality,
Food Toxicology and non-food concerns of
Instructor: Gregory Möller, Ph.D. food irradiation.
University of Idaho Explore the consumer opinions
of food irradiation.
Explore the current food uses
and future of food irradiation.
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Food Toxicology Food Toxicology
Food Irradiation Ionizing Radiation
Food irradiation is the exposure of food products to Ionizing radiation is from X-rays or radioactive decay
ionizing radiation to destroy microorganisms, insects, – Alpha particles, beta particles, gamma rays
and parasites that cause disease and spoilage Can cause chemicals reactions and alterations of
Compare to non-ionizing radiation chemicals in tissues
– Cooking - IR – Can be toxic or fatal to humans in high dose
– Microwave ovens Much of the reactivity in
organisms is with water.
Produces:
-
– Superoxide radical (O2)
Hydroxyl radical (HO)
Hydroperoxyl radical (HOO)
and hydrogen peroxide.
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Food Toxicology Food Toxicology
Ionizing Radiation Radioactive Decay
Recall “oxidative stress” from free radicals Manahan The decrease in the amount
– Endpoints: lipid peroxidation, DNA strand breaks, enzyme of any radioactive material
inactivation, covalent binding to nucleic acids, covalent with the passage of time,
binding to proteins.
Direct ionization of organic molecules can yield due to the spontaneous
carbonium ions CH3+ emission from the atomic
– Can alkylate DNA. nuclei of either alpha or beta
Example: Radon, a noble gas particles, often accompanied
that emits alpha particles by gamma radiation.
– Results from the decay of U and
Ra in naturally occurring minerals. 60 60 -
– Accumulates in basements of Co → Ni + e + νe
some homes
Presents the most risk of any NC-DRP
5 element to humans. 6
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Food Toxicology Food Toxicology
Cobalt-60 Radioactive Decay Alpha Particle
Co60 Half-life A positively charged particle ejected spontaneously
27 5.24 years from the nuclei of some radioactive elements.
0.31 MeV β – Low penetrating power and a short range.
28Ni60* The most energetic alpha particle will generally fail to
penetrate the dead layers of cells covering the skin.
1.17 MeV γ Alphas are hazardous when
an alpha-emitting isotope is
28Ni60* inside the body.
1.33 MeV γ
28Ni60
7 8 NC-DRP
Food Toxicology Food Toxicology
Beta Particle Gamma Ray
A charged particle emitted from a nucleus during High-energy, short wavelength, electromagnetic
radioactive decay. NC-DRP radiation (photon; a packet of energy) emitted from
– Mass equal to 1/1837 that of a proton. the nucleus.
– A negatively charged beta particle is identical to an – Gamma radiation frequently accompanies alpha and beta
electron; a positively charged beta particle is called a emissions and always accompanies fission.
positron. – Ionizing radiation.
Large amounts of beta Gamma rays are very penetrating
radiation may cause skin
burns, and beta emitters and are best stopped or shielded
are harmful if they enter by dense materials, such as
the body. lead or uranium.
Beta particles may be Gamma rays are similar to
stopped by thin sheets X-rays: no mass or charge.
9 of metal or plastic. 10
NC-DRP
Food Toxicology Food Toxicology
Electromagnetic Spectrum Measurements of Radiation
Visible One gray (Gy) is the absorption of one joule of
0.4 0.7
radiation energy by one kilogram of matter
UV IR 1 Gy = 1 J/kg
Wavelength, μm – Gray (Gy) = 100 rads
-6 -5 -4 -3 -2 -1 2 3 4 5 6 7 8 – rad is older unit
10 10 10 10 10 10 1101010 10 10 10 10 10
"radiation absorbed dose".
Kilogray (kGy) = 1000 Gy
γ-Rays Ultraviolet Thermal IR Radio
X-Rays Near, Mid IR Microwave
11 12
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Food Toxicology Food Toxicology
Lethal Doses Food Irradiation
Vegetative bacteria - 0.5-10 kGy Radiation energy applied to food; does not induce
Bacterial spores - 10-50 kGy radioactivity
People and animals - 0.005 - 0.01 kGy Uses γ radiation (ionizing radiation from Co60 or Cs137
Insects - 0.1-1.0 kGy decay), X-rays (high energy photon from accelerated
- - -
e colliding with W metal), or accelerated e (e beams
from accelerators)
Passes through food w/o
generating intense heat
Will disrupt some cellular
processes (i.e. DNA)
– Sprouting, microorganisms, etc.
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Food Toxicology Food Toxicology
Historical Historical
1895 - X-rays discovered Cost and scarcity of radiation sources reduced
1896 - suggested use in food preservation industry interest
1903 - process patented by US and France Adverse sensory attribute were a problem
– Destruction of Trichinella in pork Military research continued
– Stable field rations
Röntgen
15 Radiograph 16
Food Toxicology Food Toxicology
Historical Historical
1962 - Army research facility in Massachusetts 1958 - FDA ruled irradiation sources as food additives
Demonstrated meat shelf-life in years w/o Part of Food Additives Amendment
refrigeration Delayed commercialization
Performed many safety studies Industry lost interest
– Basis for much toxicology data Late 1960s - FDA approved
irradiation of potatoes
(sprout inhibition)
and grains
(reduce insect infestation)
17 18
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Food Toxicology Food Toxicology
Historical Food Irradiation Processes: Categories
1965 - Surgeon General announced irradiated foods Rad-urization
were safe and wholesome Rad-icidation
NASA adopted for space program Rad-apperization
1991 - First US commercial irradiation plant
– Vindicator of Florida, Inc. Based on radiation dose
NASA
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Food Toxicology Food Toxicology
Radiation Processes Strawberries, 1 KGy, 25 Days @ 3 ºC
Radurization: (0.75-2.5 kGy)
Inhibit sprouting, delay ripening, insect disinfestations
and shelf-life extension
Mimics pasteurization
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Food Toxicology Food Toxicology
Radiation Processes Radiation Processes
Radicidation: (2.5-10 kGy) Radapperization: (10-50 kGy)
Eliminate spoilage microorganisms and non-spore- Reduction of microorganisms to the point of
forming pathogens sterility
Problem - food will not spoil but still may contain –12D process for C. botulinum (30-45 kGy)
some pathogens 12 log cycle spore reduction: 99.9999999999%
Not approved for general use
on food
Diets for immuno-deficient
Military and NASA operations
Listeria
23 monocytogenes 24
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