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What is Food Irradiation. Food irradiation is a process in which food products are exposed to a controlled amount of radiant energy to increase the safety of the food and to extend shelf life of the food

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what is food irradiation
What is Food Irradiation
  • Food irradiation is a process in which food products are exposed to a controlled amount of radiant energy to increase the safety of the food and to extend shelf life of the food
  • Like pasteurization of milk and pressure cooking of canned foods, treating food with ionizing radiation can kill bacteria and parasites that would otherwise cause foodborne disease.
irradiation also known as
Irradiation….also known as:
  • Ionizing radiation
  • Surface pasteurization
  • Electronic pasteurization
  • E-beam sterilization/pasteurization
ionizing radiation
Ionizing radiation
  • When radiation strikes other material, it transfers energy.
  • This can cause heating, as with microwave cooking, or if there is enough energy, it can knock electrons out of the material bombarded, breaking the molecular structure-thus leaving ions (free radicals) hence the name ionizing radiation.
electromagnetic spectrum
Electromagnetic Spectrum

High Frequency

Short Wavelengths

Low Frequency

Long Wavelengths

sources of ionizing irradiation
Sources of Ionizing irradiation
  • Gamma sources of irradiation
  • X-ray machines
  • Electron accelerators
gamma rays
Gamma () rays
  • energy comes from decay of radioactive isotopes
    • Cobalt-60 (half life of 5.3 years)
      • Produced by neutron bombardment
    • Cesium-137 (half life of 30 years)
      • By-product of spent nuclear fuel
gamma rays7
Gamma () rays
  • Isotope is contained and stored in pool of water and raised when produce is to be exposed to-rays
  • facility is concrete chamber with 6-12’ thick walls
  • completely penetrates product and packaging (pallets)
electron beam
Electron-beam
  • electricity is power source-switch on and off
  • uses stream of high-energy electrons accelerated at near the speed of light
  • electrons are showered on the product
  • facilities are shielded with concrete or steel walls
  • penetrates approximately 2-3” of product and packaging
  • ideal for thin ground beef patties
how ionizing radiation works
How ionizing radiation works
  • Electrons disrupt the DNA chain either destroying or preventing reproduction of the organism
factors affecting irradiation effectiveness against microorganisms in foods
Factors affecting irradiation effectiveness against microorganisms in foods
  • Growth phase of microorganism
  • Type of food (lean vs fat)
  • Moisture content (water level)
  • Temperature of food (frozen vs heated)
  • Presence of oxygen (aerobic vs anaerobic)
irradiation dosage
Irradiation Dosage
  • Dose - amount of energy transferred
    • rad - old unit
    • gray (Gy) - new unit
    • 1 kGy = 100,000 rad
  • 1 chest X-ray = .01 rad
  • natural background = 0.1 rad/year
typical irradiation d values of pathogens
Typical irradiation D-values of pathogens

D-value is equivalent to radiation dose required to reduce a bacterial population 90%

typical irradiation d values of pathogens16
Typical irradiation D-values of pathogens

D-value is equivalent to radiation dose required to reduce a bacterial population 90%

destruction of microorganisms
Destruction of microorganisms

IrradiationkGy dose 1 D value

Contains 10 microorganisms

1 microorganism survives

Irradiation kGy dose 2 D value

Contains 10 microorganisms

1 microorganism survives/ 10 steaks

pasteurization
Pasteurization
  • To reduce microorganisms but not to sterilize the product
  • Purpose is to destroy pathogenic microorganisms to make food safe
  • This is normally 5 to 7 D values
effect of irradiation on shelf life of fresh meats
Effect of irradiation on shelf life of fresh meats
  • Spoilage organisms, especially pseudomonads, are susceptible to low dose irradiation
  • Spoilage of low dose irradiated meats may be due to yeast, LAB, or Moraxella spp. (increased lag time)
how does irradiation food processing operation work
How does irradiation food processing operation work?
  • Food is packed in containers and moved by conveyer belt into a shielded room.
  • Food is exposed briefly to a radiant-energy source.

(The amount of energy depends on the food.)

  • Food is left virtually unchanged, but the number of harmful bacteria, parasites and fungi is reduced and may be eliminated.
electron beam24
Electron-beam

Dosimeter

levels of food irradiation
Levels of Food Irradiation
  • Radurization (low) < 1 kGy
    • vegetable sprouting, fruit ripening, insect sterilization
  • Radicidation (medium) 1-10 kGy
    • kills most pathogens and many food spoilage organisms, kills insects and parasites
  • Rappertization (high) > 10kGy
    • can sterilize by killing all bacteria and viruses
meat irradiation
Meat Irradiation
  • December 23, 1999 Federal Register
  • Effective date – February 22, 2000
  • Ionizing radiation approved for use
    • Cobalt-60, Cesium-137, X-ray machines, Electron accelerators
  • Dosage
    • 4.5 kGy if refrigerated
    • 7.0 kGy if frozen
safety and efficacy of food irradiation
Safety and efficacy of food irradiation
  • The following statements are in the Federal Register (12/23/1999)
  • The safety and efficacy of food irradiation, as demonstrated by numerous experiments and studies, is widely accepted by Federal regulatory agencies and national and international food and public health organizations
  • FDA examined numerous studies on the chemical effects of radiation, the impact of radiation on nutrient content of foods, potential toxicity concerns and effects on microorganisms in or on irradiated products. FDA concluded that irradiation is safe in reducing disease-causing microbes in or on meat food products and it does not compromise the nutritional quality of treated products.
  • The World Health Organization, Food and Agriculture Organization, American Medical Association and American Dietetic Association endorse food irradiation
web sites of interest
Web sites of interest
  • http://www.fsis.usda.gov/OA/topics/irrmenu.htm
  • http://www.acsh.org/publications/booklets/irradiated.pdf
  • http://www.ers.usda.gov/Topics/view.asp?T=102818
  • http://www.fda.gov/opacom/catalog/irradbro.html
  • http://www.fsis.usda.gov/OA/topics/irrad-risk.htm