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Who is the leader in design of food and medical irradiators?
Who discovered radioactivity?
How was radioactivity discovered?
By noting that photographic negatives became exposed when placed close to certain types of rocks
What is radioactivity?
Decay of nucleus of unstable atoms with the release of energetic radiation
What is the major application of atomic energy?
What are some important practical uses of atomic energy?
- Sterilization of medical supplies
- Cancer treatment
- Food irradiation
What are the main uses of atomic energy in relation to food?
- Insect disinfestation
- Sterilization of spices
- Shelf life extension
- Sprout inhibition
- Control of endemic salmonella in poultry
Why is it difficult to promote the use of food irradiation in North America?
Because of its association with the atom bomb and radiation
What is food irradiation based on?
The use of Ionizing radiation
What end of the electromagnetic spectru mdoes food irradiation use?
High energy, Short wavelength
What characteristics does all energy have?
Both wave-like and particle-like characteristics
What characteristic does the low energy portion of the electromagnetic spectrum mostly exhibit in nature?
Low energy portion of the electromagnetic spectrum is largely wave-like in nature
What characteristic does the high energy portion of the electromagnetic spectrum mostly exhibit in nature?
High energy end is more particulate-like in nature
How do some isotopes induce nuclear decay?
Depending on isotopes, some forms emitted radiation have sufficient energy to perturb the nucleus of other atoms and induce nuclear decay in them and make them radioactive
What are some isotopes that can induce nuclear decay
Plutonium and Uranium
What is ionizing radiation?
Radiation which is less energetic
What are some typical isotope breakdown products emitted?
- Gamma rays
- Beta particles (electrons)
- Alpha particles (He nuclei)
Which emitted products meet the criteria of being ionizing radiation?
Which isotopes are used for food irradiation?
Only isotopes which emit ionizing lecels of radiation
What would happen if non-ionizing levels of radiation were used for food irradiation?
The food product would become radioactive upon exposure
What are the types of ionizing radiation?
- Alpha Particles
- Beta Particles (rays)
- Gamma Rays
What are alpha particles?
Helium nucles minus 2 electrons, heavy and low penetration (not useful)
What are Beta Particles (rays)?
High energy electrons- low penetration (useful in certain circumstances- eg thin producs like plastic films)
What are Gamma rays?
Mich like an x-ray- high penetration (food processing)
What are the two types of radiation that are usaeful for food processing?
Gamma rays and Beta rays
How are gamma rays predominanly produced?
From cobalt 60
What does Cobalt 60 produce?
2 Gamma and 1 beta ray
What is an alternative method of radiation?
What is 'intensity' of radiation?
- Refers to energy of the irradiation source
- Can be compared to the temperature of a retort
Whar are the two ways of expressing source energy?
What is Roentgen?
Radiation recieved in 1Hr from 1g of radium at a distance of 1 yard to produce 2.08*109 ion pairs per cubic centimeter
What is Curie (Ci)?
Disintegrations per second?
What is 'dosage' of radiation?
Refers to amount of energy absorbed by a product- can be compared to the integrated lethality of a thermal process
Which has better penetrating power, Gamma rays, or Beta rays?
What happens when beta rays produced by a linear accelerator exceed 1.6*1012J?
They will induce muclear decay
What is the main purpose of ionizing irradiation?
To kill/inactivate microorganisms, insects and disrupt biological processes
What is microbial destruction by irradiation based on?
Disruptice reactions cause by the free radicals produced by ionization of molecules essential to life processes
What are the primary objectives of food irradiation?
- Food preservation
- Insect Disinfestation
- Improved quality
Which are more difficult to irradiate effectively, wet or dry foods?
How does irradiation differ in wet and dry systerms?
In foods containing significant levels of moisture, the indirect effects are more significant than the direct effects and are predominantly due to the radiolysis of water
How does water effect irradiation?
Water present in food is activated to form reactive free radicals
What reactions does the water radicals lead to?
Formation of oxidation products, such as hydroperoxides, alcohols, aldehydes, FFA
What does the formation of oxidation products result in?
Off flavors and quality changes which are highly product dependant
How can off flavors and quality changes by irradiation be minimized?
If the products to be irradiated are frozen or through the use of antioxidants- both expensive and generally not practical
How much radiation is required to produce satisfactory commercially sterile bacon?
What happens if egg white takes more than 0.06 MRADs of radiation?
The egg white becomes wattery and unacceptable
Because egg white cannot withstand radiation, what is the only acceptable method of sterilization?
What is the general irradiation dose to produce commercial sterility (12D)?
What is the general irradiation dose to produce shelf extensiom/ pasteurization?
What is the general irradiation dose to kill yeasts and molds?
What is the general irradiation dose to destroy insects/inhibit sprouting?
What is the general irradiation dose for human localized tumor treatment?
What types of food is irradiation excellent for?
temperature sensitive products such as fruits and vegetables
Which logo must irradiated foods bear?
Which products can be irradiated to commercial sterility without adverse organoleptic effects?
- Some Vegetables
Why can fish only be pasteurized?
High doses of irradiation can cause major organoleptic problems (usually lipid oxidation)
Which organism is the main concern of food irradiation?
What is the key driving force for renewed interest in food irradiation is USA?
Control of newly emergent food-bornw diseases
What is a common way of measuring the dose of irradiation?
Cobalt glass dosimeters
How do cobalt glass dosimeters work?
Cobalt glass darkens cumulatively upon exposure to ionizing radiation
What is a limitation of food irradiation?
Food irradiation is quite inefficient relative to thermal processing in knocking out enzymes
What is done to vegetables before irradiation to reduce enzymatic deterioration?
What are the two food irradiation facilities in Canada?
- Armand Frappier Institute (Cresela)
- Food Research and Development Center (St. Hyacinthe)
Food irradiation has been shown to be very beneficial in terms of what?
- Insect disinfestation
- Sterilizing Spices
- Prevention of sprouting
- Meal preparation for immune deficient patients
- Control of food-borne diseases
How does food irradiation sterilize spices?
Relplaces ethylene oxide/ethylene dibromide- commonly used fumigants
Who benefits the most from food irradiation?
Exporting developing tropical countries which have fewer processing technology choices
What is Nordion?
Manufactures medical and food irradiators- sells most abroad
What is the most practical irradiation application?
To obtain shelf life extension
Which foods do not have labeling requirements when sterilized by food irradiation?
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