Ionizing Energy
Lesson 10
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Assigned Readings – n Smith, J.S. and Pillai, S. 2004. Irradiation and Food safety. Food Technol. n Fact sheet on Food Irradiation http://www.inspection.gc.ca/food/information-for-consumers/fact-sheets/labelling-food-packaging-and-storage/irradiation/eng/1332358607968/1332358680017 n
Frequently Asked Questions regarding Food Irradiation
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Terminology n Radiation
¨
¨
n
Food irradiation
¨
n
Rays of energy
Emission and propagation of energy through matter or space by electromagnetic disturbances
Application of radiation, as ionizing energy, to foods
Electromagnetic spectrum ( of radiation)
Radiation Is the Energy!
Irradiation Is the Process!
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Terminology n n
Electromagnetic spectrum (of radiation)
Organized scale of electromagnetic radiation:
¨ radio
waves,
¨ visible light,
¨ microwaves,
¨ ionizing radiation n frequency, wavelength, energy value lower frequency, wider wavelength more frequency, more energy value, smaller wavelength
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Long wavelength,
Low Energy
Aircraft & shipping bands
AM Radio bands
T.V. and FM Radio bands
Microwaves, Radar
Infrared
Visible
Ultraviolet
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Electromagnetic Energy: Microwave Energy
(long wavelengths- Low penetrating power) in food- cause polar molecules to vibrate Heat by intermolecular friction l Heat then conducted to neighboring molecules l
l
n n MW absorbed by food up to a depth of 5 to 7.5 cm
Pass through air, glass, paper and plastic
Reflected by metals
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Long wavelength,
Low Energy
Aircraft & shipping bands
AM Radio bands
T.V. and FM Radio bands
Microwaves, Radar
Infrared
Visible
Ultraviolet
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Visible
Ultraviolet
X-rays
Ionizing radiation
Gamma
rays
Short wavelength,
High Energy
Electromagnetic Energy: Ionizing Radiation
(short wavelengths- High penetrating power)
Ionizing radiation: n X-rays
n
Gamma rays, etc
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Ionizing Radiation l Food Irradiation l Uses Beta & Gamma rays or electron accelerators l Short wavelength, high