Lecture 13: Irradiation Flashcards
(33 cards)
are there commercial irradiation facilities in canada? what kinds are there?
no
irradiation facilities for research in industry, government, university
what are 2 types of irradiation technologies?
compare them
- man made radio isotopes
- electron accelerators
- both have comparable efficiency
- both must be installed in a shielded room to allow treatment to take place w/o compromising health of operators
- uses batch or continuous processes
describe the use of beta rays
- suitable for thin layers
- low energy
- uses electron accelerators (simple to operate and low cost)
describe labelling requirements for irradiated food
- identification of the irradiated food pdt or ingredient using the international symbol if it makes up more than 10% of the pdt content
- written statement that food has been irradiated
1 gray = ____ rad?
100 rad
rate the dose of radiation from smallest to highest
a) sprouting inhibited
b) lethal to insects
c) sterilization of MOs
d) no acute effects
e) lethal to humans
- no acute effects (1-100 rad)
- lethal to humans (100-1000rad)
- sprouting inhibited
- lethal to insects
- sterilization of MOs (1000 to 10^7 rad)
regulatory agencies determine what?
- which food may be treated by irradiation
- under what conditions
- for what purpose
- prescription of what type of information should be included in the label
in 1983, the codex alimentarious commission accepted what?
that foods irradiated up to 10kGy was safe and wholesome and toxicological testing was no longer necessary
what is the codex general standard of irradiated foods?
used for regulations of irradiated food for different countries
in 1986, why did RDA issue a regulation for a max dose of irradiation?
for:
- insect desinfestation
- ripening, growth and maturation inhibition
- applications to foods and specified radiation
- labelling with international logo
- use of radioisotopes
- no specific licensing for plant facilities
what is the USNRC?
united states nuclear regulation commission
what is AECB? what is it now named?
atomic energy control board
now named nuclear safety commission
what is dosimetry?
measurement of radiation dose
what is a dosimeter?
instrument for measuring dose
what is the role of dosimetry in food irradiation?
- to administer proper dose
- for commissioning food pdt through regulatory agency
- to establish quality control procedure in the food pdt plant
- to optimize configuration of the irradiation field after the installation of the irradiator or any changes that would occur in the irradiation facility
what is considered a low or low dose?
low dose: 0.6 to 10kGy
high dose: 5 to 50 kGy
in dosimeters, ceric ions are reduced to what?
cerous ions
what is one of the most useful reference dosimeters?
Fricke (ferous feric)
describe the Fricke ferous feric dosimeteter
- aqueous solutions of Fe+2 ions oxidized to Fe+3 ions with O2
- uses UV spectrophotometer to determine conc of Fe+3 at 305nm
- dose range of 0.02 to 0.4kGy
what are post harvest applications of radiation preservation?
- sprout inhibition of potato, garlic, onions
- insect desinfestation of fruits, grains, spices
- reduction of microbial load
- shelf life extension
- control of pathogenic organisms in food
what are benefits of radiation preservation?
- low energy consumption
- environmental cleanliness
- potential to reduce use of fumigants and pesticides
what are advantages of irradiation?
- killing microbial contaminants
- sterilizing or killing adult insects, larvae and eggs
- can be applied to fruits in a fresh state
- physical process
- high reliability
what are effects of radiation on polysaccharides?
partly depolymerized cellulose, pectin and starch
what are effects of radiation on proteins?
- they are less affected although reduction of disulfide bonds may lead to inactivation of active site and conformational changes in enzymes
