Food Sci-1

  1. Who is the leader in design of food and medical irradiators?
  2. Who discovered radioactivity?
    Madame Curie
  3. How was radioactivity discovered?
    By noting that photographic negatives became exposed when placed close to certain types of rocks
  4. What is radioactivity?
    Decay of nucleus of unstable atoms with the release of energetic radiation
  5. What is the major application of atomic energy?
    Generating electricity
  6. What are some important practical uses of atomic energy?
    • Sterilization of medical supplies
    • Cancer treatment
    • Food irradiation
  7. 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
  8. Why is it difficult to promote the use of food irradiation in North America?
    Because of its association with the atom bomb and radiation
  9. What is food irradiation based on?
    The use of Ionizing radiation
  10. What end of the electromagnetic spectru mdoes food irradiation use?
    High energy, Short wavelength
  11. What characteristics does all energy have?
    Both wave-like and particle-like characteristics
  12. 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
  13. What characteristic does the high energy portion of the electromagnetic spectrum mostly exhibit in nature?
    High energy end is more particulate-like in nature
  14. 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
  15. What are some isotopes that can induce nuclear decay
    Plutonium and Uranium
  16. What is ionizing radiation?
    Radiation which is less energetic
  17. What are some typical isotope breakdown products emitted?
    • Gamma rays
    • Protons
    • Beta particles (electrons)
    • Alpha particles (He nuclei)
  18. Which emitted products meet the criteria of being ionizing radiation?
    • Gamma rays
    • Electrons
  19. Which isotopes are used for food irradiation?
    Only isotopes which emit ionizing lecels of radiation
  20. What would happen if non-ionizing levels of radiation were used for food irradiation?
    The food product would become radioactive upon exposure
  21. What are the types of ionizing radiation?
    • Alpha Particles
    • Beta Particles (rays)
    • Gamma Rays
  22. What are alpha particles?
    Helium nucles minus 2 electrons, heavy and low penetration (not useful)
  23. What are Beta Particles (rays)?
    High energy electrons- low penetration (useful in certain circumstances- eg thin producs like plastic films)
  24. What are Gamma rays?
    Mich like an x-ray- high penetration (food processing)
  25. What are the two types of radiation that are usaeful for food processing?
    Gamma rays and Beta rays
  26. How are gamma rays predominanly produced?
    From cobalt 60
  27. What does Cobalt 60 produce?
    2 Gamma and 1 beta ray
  28. What is an alternative method of radiation?
    Linear Accelerators
  29. What is 'intensity' of radiation?
    • Refers to energy of the irradiation source
    • Can be compared to the temperature of a retort
  30. Whar are the two ways of expressing source energy?
    • Roentgen
    • Curie (Ci)
  31. 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
  32. What is Curie (Ci)?
    Disintegrations per second?
  33. 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
  34. Which has better penetrating power, Gamma rays, or Beta rays?
    Gamma rays
  35. What happens when beta rays produced by a linear accelerator exceed 1.6*1012J?
    They will induce muclear decay
  36. What is the main purpose of ionizing irradiation?
    To kill/inactivate microorganisms, insects and disrupt biological processes
  37. What is microbial destruction by irradiation based on?
    Disruptice reactions cause by the free radicals produced by ionization of molecules essential to life processes
  38. What are the primary objectives of food irradiation?
    • Food preservation
    • Insect Disinfestation
    • Improved quality
  39. Which are more difficult to irradiate effectively, wet or dry foods?
  40. 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
  41. How does water effect irradiation?
    Water present in food is activated to form reactive free radicals
  42. What reactions does the water radicals lead to?
    Formation of oxidation products, such as hydroperoxides, alcohols, aldehydes, FFA
  43. What does the formation of oxidation products result in?
    Off flavors and quality changes which are highly product dependant
  44. 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
  45. How much radiation is required to produce satisfactory commercially sterile bacon?
    5.6 MRADs
  46. What happens if egg white takes more than 0.06 MRADs of radiation?
    The egg white becomes wattery and unacceptable
  47. Because egg white cannot withstand radiation, what is the only acceptable method of sterilization?
  48. What is the general irradiation dose to produce commercial sterility (12D)?
    ~2.5 MRADs
  49. What is the general irradiation dose to produce shelf extensiom/ pasteurization?
  50. What is the general irradiation dose to kill yeasts and molds?
    200-500 KRads
  51. What is the general irradiation dose to destroy insects/inhibit sprouting?
    10 KRads
  52. What is the general irradiation dose for human localized tumor treatment?
  53. What types of food is irradiation excellent for?
    temperature sensitive products such as fruits and vegetables
  54. Which logo must irradiated foods bear?
    "Radura" logo
  55. Which products can be irradiated to commercial sterility without adverse organoleptic effects?
    • Prok
    • Shrimp
    • Bacon
    • Chicken
    • Some Vegetables
  56. Why can fish only be pasteurized?
    High doses of irradiation can cause major organoleptic problems (usually lipid oxidation)
  57. Which organism is the main concern of food irradiation?
    C. Botulinum
  58. What is the key driving force for renewed interest in food irradiation is USA?
    Control of newly emergent food-bornw diseases
  59. What is a common way of measuring the dose of irradiation?
    Cobalt glass dosimeters
  60. How do cobalt glass dosimeters work?
    Cobalt glass darkens cumulatively upon exposure to ionizing radiation
  61. What is a limitation of food irradiation?
    Food irradiation is quite inefficient relative to thermal processing in knocking out enzymes
  62. What is done to vegetables before irradiation to reduce enzymatic deterioration?
  63. What are the two food irradiation facilities in Canada?
    • Armand Frappier Institute (Cresela)
    • Food Research and Development Center (St. Hyacinthe)
  64. 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
  65. How does food irradiation sterilize spices?
    Relplaces ethylene oxide/ethylene dibromide- commonly used fumigants
  66. Who benefits the most from food irradiation?
    Exporting developing tropical countries which have fewer processing technology choices
  67. What is Nordion?
    Manufactures medical and food irradiators- sells most abroad
  68. What is the most practical irradiation application?
    To obtain shelf life extension
  69. Which foods do not have labeling requirements when sterilized by food irradiation?
Card Set
Food Sci-1
Food Sci-1