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Questions and Answers
What is food irradiation primarily used for?
What is food irradiation primarily used for?
Food becomes radioactive after being irradiated.
Food becomes radioactive after being irradiated.
False (B)
What effect does irradiation have on the DNA of microorganisms?
What effect does irradiation have on the DNA of microorganisms?
It breaks the bonds in DNA molecules, causing defects that can lead to death or inability to reproduce.
Food irradiation is also known as __________.
Food irradiation is also known as __________.
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Match the following food items with their potential uses for irradiation:
Match the following food items with their potential uses for irradiation:
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Which of the following statements about the effectiveness of irradiation is true?
Which of the following statements about the effectiveness of irradiation is true?
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Irradiation can delay the ripening of certain vegetables.
Irradiation can delay the ripening of certain vegetables.
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In which types of food does irradiation require a larger radiation dose to be effective?
In which types of food does irradiation require a larger radiation dose to be effective?
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What is the primary target of ionizing radiation in microbial inactivation?
What is the primary target of ionizing radiation in microbial inactivation?
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Gamma rays can make surrounding materials radioactive.
Gamma rays can make surrounding materials radioactive.
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What are the two types of radionuclides mentioned that emit gamma rays?
What are the two types of radionuclides mentioned that emit gamma rays?
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Irradiation helps prolong the shelf life of fruits and vegetables by inhibiting _____ and delaying ripening.
Irradiation helps prolong the shelf life of fruits and vegetables by inhibiting _____ and delaying ripening.
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Match the radiation type with its description:
Match the radiation type with its description:
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Which of the following is a disadvantage of using Cobalt-60 for food irradiation?
Which of the following is a disadvantage of using Cobalt-60 for food irradiation?
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The half-life of Cobalt-60 is longer than that of Cesium-137.
The half-life of Cobalt-60 is longer than that of Cesium-137.
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What is the purpose of storing the radioactive source in water when not in use?
What is the purpose of storing the radioactive source in water when not in use?
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What is the maximum energy of an accelerated electron?
What is the maximum energy of an accelerated electron?
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X-rays are produced by colliding electrons with a metallic target.
X-rays are produced by colliding electrons with a metallic target.
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What is one advantage of using accelerated electrons over radioactive materials for food treatment?
What is one advantage of using accelerated electrons over radioactive materials for food treatment?
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The depth of penetration of an electron beam can reach up to _____ centimeters.
The depth of penetration of an electron beam can reach up to _____ centimeters.
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Which of the following is a disadvantage of using accelerated electrons?
Which of the following is a disadvantage of using accelerated electrons?
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Which radiation type is most penetrating and useful for packed food?
Which radiation type is most penetrating and useful for packed food?
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Match the type of radiation with their characteristics:
Match the type of radiation with their characteristics:
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Electron beams do not require any kind of shielding.
Electron beams do not require any kind of shielding.
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The maximum permitted dose of irradiation for food is 10 Gy.
The maximum permitted dose of irradiation for food is 10 Gy.
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What is the unit currently used to measure radiation dose absorbed by food?
What is the unit currently used to measure radiation dose absorbed by food?
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What is the efficiency rate of conversion from electrons to X-rays?
What is the efficiency rate of conversion from electrons to X-rays?
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Irradiation is often referred to as a 'cold __________' process.
Irradiation is often referred to as a 'cold __________' process.
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Match the following effects with their descriptions:
Match the following effects with their descriptions:
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What is the old unit of measurement for radiation absorbed dose?
What is the old unit of measurement for radiation absorbed dose?
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Electron beams have a higher penetrating power than gamma rays.
Electron beams have a higher penetrating power than gamma rays.
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What effect does irradiation have on bacterial cellular membranes?
What effect does irradiation have on bacterial cellular membranes?
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What is one of the primary applications of food irradiation?
What is one of the primary applications of food irradiation?
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Food irradiation only affects the safety of meat products.
Food irradiation only affects the safety of meat products.
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Name one benefit of food irradiation.
Name one benefit of food irradiation.
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Irradiation at ___ kGy is used for controlling disease-causing microorganisms in poultry.
Irradiation at ___ kGy is used for controlling disease-causing microorganisms in poultry.
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Match the type of food with its corresponding approved use and dose:
Match the type of food with its corresponding approved use and dose:
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Which of the following is a disadvantage of food irradiation?
Which of the following is a disadvantage of food irradiation?
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What does the Radura logo indicate?
What does the Radura logo indicate?
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Irradiation helps in delaying the ripening process of fruits and vegetables.
Irradiation helps in delaying the ripening process of fruits and vegetables.
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Which factor is NOT considered when determining the irradiation dose for food products?
Which factor is NOT considered when determining the irradiation dose for food products?
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Higher animals require a radiation dose of 0.005 to 0.10 kGy to be killed.
Higher animals require a radiation dose of 0.005 to 0.10 kGy to be killed.
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What is the range of radiation doses required for disinfestation and sterilization of food?
What is the range of radiation doses required for disinfestation and sterilization of food?
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The process of _______ reduces the number of non spore-forming pathogenic bacteria with a dose range of 3 to 10 kGy.
The process of _______ reduces the number of non spore-forming pathogenic bacteria with a dose range of 3 to 10 kGy.
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Match the following types of radiation application with their dose ranges:
Match the following types of radiation application with their dose ranges:
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Which of the following food items requires a medium dose of radiation (1 kGy to 10 kGy) for pathogen reduction?
Which of the following food items requires a medium dose of radiation (1 kGy to 10 kGy) for pathogen reduction?
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Vitamin D is one of the vitamins known to have loss due to irradiation.
Vitamin D is one of the vitamins known to have loss due to irradiation.
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What effect does irradiation have on the gelling power of pectin in carbohydrates?
What effect does irradiation have on the gelling power of pectin in carbohydrates?
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Study Notes
Food Irradiation
- Food irradiation is a process where food is exposed to a controlled amount of ionizing radiation to achieve desired objectives.
- It's considered a food additive.
- It can sterilize packaging materials, destroy pathogens (e.g., Salmonella), prevent spoilage by microorganisms, delay ripening, inactivate parasites, and inhibit sprouting in vegetables.
- Cold pasteurization is another name for ionizing radiation. It has the same goal as thermal pasteurization for liquid foods (e.g., milk), but without significantly raising the product's temperature.
- It's used in over 40 countries on more than 100 food items, including potatoes, onions, cereals, flour, fresh fruit, and poultry.
Electromagnetic Spectrum
- The electromagnetic spectrum displays various types of electromagnetic radiation.
- It ranges from cosmic rays to radio waves, with visible light being a part of it.
- Radiation types include (from high to low frequency/long to short wavelengths): Gamma rays, X-rays, Ultraviolet (UV), Visible light, Infrared (IR), Microwaves, and Radio waves.
- Sunlight contains various types of infrared radiation.
How Irradiation Works
- The energy from irradiation breaks bonds in DNA molecules of microbes resulting in defects in their genetic instructions.
- If this damage can't be repaired, the microbe dies or can't reproduce.
- The effectiveness of the process depends on the organism's sensitivity to radiation, its DNA repair rate, and the amount of DNA in the organism.
- Parasites and insect pests, with much DNA, are quickly killed. Bacteria, with less DNA, require a higher dose.
- Viruses are generally resistant to irradiation doses used for food.
- Radiation works through two mechanisms: direct interaction with cell components (primarily targeting chromosomal DNA and affecting cell membrane structure) and indirect action from radiolytic products like water radicals.
Types of Radiation Used in Food
- Gamma rays: Generated by the spontaneous disintegration of radioisotopes (e.g., cobalt-60 and cesium-137).
- Accelerated electrons: Generated by electron guns and accelerators, increasing electron speed to the speed of light.
- X-rays: Generated by colliding electrons with metallic targets (e.g., tungsten, gold).
Gamma Rays (Specifics)
- Gamma rays are high-frequency electromagnetic energy released by radioactive substances.
- Common radioactive substances in food irradiation include cobalt-60 (half-life of 5.3 years) and cesium-137 (half-life of 30 years).
- Irradiation using gamma rays requires shielding concrete.
How Irradiation Works (Detailed)
- The process involves putting food in special, radiation-resistant containers and exposing them to a controlled radiation source for a specified period.
- The radioactive source (such as cobalt-60) emits gamma rays which can penetrate food up to several feet.
- This process typically does not make the surrounding area radioactive.
- The process may be used for treatment of cancer, sterilization of medical equipment, and sterilization of other industrial equipment.
Advantages of Irradiation
- Reduces disease-causing microorganisms.
- Doesn't change nutritional value significantly.
- Doesn't make the food radioactive.
- A safe and effective technology for preventing foodborne illness.
- Increased shelf life for fruits and vegetables, inhibiting sprouting and slowing ripening.
Advantages of Various Irradiation Methods
- Gamma rays: Up to 95% of emitted energy is usable. Penetrates deeply (e.g., food >12 inches thick; similar to X-rays). Provides uniform dose distribution throughout the food. Decays into non-radioactive elements (nickel and barium). Low environmental risk.
- Accelerated electrons: Can be turned on/off as needed. No radioactive material required. Depth of penetration is relatively shallow (limited to approximately 3 cm, or 1 inch.) Two opposing beams can double penetration.
Disadvantages of Various Irradiation Methods
- Gamma rays: Co-60 pencils require frequent replenishment and are "always on."
- Accelerated electrons: High electricity consumption; more complex and costly apparatus with higher maintenance.
X-rays
- Produced by colliding electrons with metal targets (e.g., tungsten, gold.)
- Better penetrability than electron beams.
- Much lower than the efficiency of electrons converted to X-rays (efficiency <10%).
- Recent (new technology).
- X-ray machines have similar functionality like imaging equipment used in hospitals and clinics, requiring shielding.
Radiation Dose
- Dose is measured in Grays (Gy) – amount of energy absorbed per kilogram of food.
- Dose used depends on the specific food, desired outcome and type of organism present in it. International standards specify maximum safe dosages.
- Higher doses are needed to control bacteria than parasites.
- Doses are characterized differently for different types of food, and differ depending on the objectives of irradiation.
Effect of Irradiation on Food Quality
- Radiation can cause free radical formation; this can lead to off-flavors (e.g., meat and eggs), changes to amino acids/ proteins, and reduced gelling power (softening) in some foods.
- Vitamin loss is possible.
Applications in Food Industry
- Inhibiting sprouting (e.g., potatoes, onions).
- Delaying ripening and aging in plants.
- Increasing juice yield (improving hydration).
- Insect sterilization (prevents proliferation).
- Eliminate risk of contamination by virulent E. Coli, salmonella and other bacteria.
- Absolute sterilization of foods for immune deficient patients and space programs.
- Treating meat, poultry, spices, and bakery products.
Types of Radiant Energy
- Ionizing radiation (e.g., gamma rays, X-rays): High enough energy to dislodge electrons from atoms or molecules changing them to ions.
- Ultraviolet light, Infrared: Lower energy to excite electrons and cause changes to certain food components, but not necessarily change all of them into ions.
Additional Notes
- The presence of a radura logo on a food product indicates the use of irradiation.
- Irradiation is a way to increase shelf life and reduce spoilage.
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Description
Explore the fundamentals of food irradiation and its applications in food preservation. This quiz covers concepts related to the effects of irradiation on microorganisms, food items that can be irradiated, and the technology involved in the process. Test your knowledge on how irradiation influences the shelf life of various foods.
