Food Irradiation Flashcards
What is food irradiation?
Preserves foods using ionizing
radiation. It does not involve heating the food to
any significant extent & sensory &
nutritional properties are therefore
largely unchanged.
What are ionizing sources?
Gamma rays and Xrays
What are sources of gamma ray?
Cobalt 60 and Cesium 137
How are xray photons obtained?
Obtained when electron beams hit
surface of tantalum or tungsten metals
Food Irradiation is the process of exposing food to
ionizing radiation to?
Destroy microorganisms, delay ripening, improve rehydration, and inhibit sprouting
Only gamma radiation &
accelerated electrons (which may
also be converted to X-rays) are
used in food processing
applications because
other
particles cause induced
radioactivity.
Electron energy is limited
to a legal maximum of?
10 MeV
X-rays are limited to a legal max of?
5 MeV
Radioisotope cobalt-60 (60Co)
has a half-life of?
5.3 years
Radioisotope cobalt-60 (60Co) emits gamma rays at two
wavelengths which have
energies of?
1.17 and 1.33 MeV
Cesium-137 (137Cs) has a half-life
of?
30.2 years
Cesium-137 (137Cs) emits gamma rays with energy of?
0.66 MeV
Gamma rays, electrons
and X-rays are
distinguished from other
forms of radiation by
their?
ionizing ability
Ionizing radiations interact
with atoms in a food (a
process known as
Compton scattering
Products of ionization
electrically charged ions or
neutral free radicals.
radiolysis
process in which free radicals and ejected
electrons, then further react to
cause changes in an irradiated
material
Hydroxyl radicals
powerful oxidizing agents and react with unsaturated compounds
Expelled electrons
react with
aromatic compounds, especially
ketones, aldehydes and
carboxylic acids.
Diffusivity of free radicals depends
on
the availability of free water in
the food
Diffusivity of free radicals depends
on
the availability of free water in
the food
Irradiation in the presence of oxygen can lead to the
formation of
ozone, hydroperoxyl radicals and superoxide
anions, which can give rise to hydrogen peroxide, all of which
are powerful oxidizing agents
What are lost during irradiation?
Fat soluble components and essential fatty acids
what is ionizing radiation?
Such forms of radiation which have
sufficiently high energy to cause
ionization
IONIZATION
Creation of ions by expulsion of
orbital electrons from atoms
MAIN BIOLOGICAL EFFECT OF IONIZING RADIATION
Inactivate living
organisms that cause
spoilage & other forms of
quality deterioration or
can cause a hazard to the
consumers’ health.
Application potential of
ionizing radiation for food
products is based mainly
on the fact that
ionizing
radiation damages DNA &
very effectively inhibits
DNA synthesis & further
cell division
6 Types of Irradiation Process
Sterilization or Radappertization
Prolonging shelf life or radurisation
Reduction of pathogens or radicidation
Control of ripening
Disinfestation
Inhibition of sprouting
Herbs & spices are frequently contaminated by
heat-resistant,
spore-forming bacteria.
Herbs & spices are sterilized using a dose of
7-10 kGy
The main advantage of irradiating spices is the
replacement of
chemical sterilization using ethylene oxide
Food poisoning bacteria can be destroyed by doses of
2.5-10 kGy
Fresh poultry carcasses irradiated with a dose of ___ are virtually free of ______ and the shelf-life
is doubled when the product is held below ___.
2.5 kGy, Salmonella, 5 degrees Celsius
In Japan, doses of about ___ have been used since
1973 on potatoes intended for further processing.
150Gy
Doses of _____ can control parasitic protozoa and
helminths in fresh fish and prevent development of insects in
dried fish
0.25 ±1.0 kGy
devices that, when
irradiated, produce a quantifiable
and reproducible physical and/or
chemical change that can be related
to the dose absorbed
Dosimeters
devices that, when
irradiated, produce a quantifiable
and reproducible physical and/or
chemical change that can be related
to the dose absorbed
Dosimeters
