Food Irradiation: 16 flashcards
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1. How are X-rays produced and how do they behave compared to Gamma rays?
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X-rays are ionizing radiations produced by bombarding a suitable metal target with high-velocity electrons. They behave like Gamma rays.
2. What does the REP unit stand for and what is its absorption value?
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REP stands for Roentgen-Equivalent Physical. 1 REP = absorption of 83 ergs/g of matter.
3. Define the RAD unit and its absorption value.
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RAD is a unit of measurement of radiation. 1 RAD = absorption of 100 ergs/g of matter. 1 K rad = 1000 rads.
4. What is the Gray (GY) unit and how does it relate to RAD?
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Gray is a newer and recently used unit of radiation. 1 Gray = 100 rads = 11 joules/kg. 1 KGy = 105 rads.
5. Name the three types of radiation processes given to food.
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1. Radappertization 2. Radicidation 3. Radurization
6. What is Radappertization and what dose does it use?
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Radappertization is a radiation process that destroys microorganisms, equivalent to commercial sterility of heat-processed foods (radiation sterilization). It uses a radiation dose of 30-40 KGy and ensures a sterile product with prolonged shelf life.
7. What is Radicidation and what dose does it use?
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Radicidation is a radiation process used for the reduction of viable non-spore-forming pathogens undetectable by standard methods. It is equivalent to pasteurization and uses 2.5-10 KGy.
8. What is Radurization and what dose does it use?
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Radurization is irradiation given to minimize the load of spoilage organisms, thus extending shelf life. It is considered equivalent to pasteurization and uses 0.75-2.5 KGy. Suitable for fresh meat, seafood, fruits, vegetables.
9. How does irradiation affect food quality negatively?
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Irradiation can cause undesirable changes directly by irradiation and indirectly by post-irradiation reactions. Free radicals cause oxidative changes leading to product discoloration, tissue softening in fruits (pectin and cellulose degradation), and rancidity in high-fat products (carbonyl and peroxide radicals).
10. How can product discoloration and rancidity from irradiation be reduced?
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By giving the radiation process at low temperature in the absence of oxygen.
11. List foods permitted for irradiation for inhibition of sprouting.
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Potatoes, onion, garlic, mushrooms, etc.
12. What is irradiation used for in cereals and grains?
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Decontamination of food ingredients (species) and insect disinfection in cereals and grains.
13. What is irradiation used for in meat, poultry, eggs, shrimps, and frog legs?
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Destruction of parasites in meat; inactivation of Salmonella in poultry, eggs, shrimps, frog legs.
14. What is irradiation used for in fruits like strawberries, mango, and papaya?
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Delay in fruit maturation.
15. What is the mechanism of the microbicidal effect of irradiation?
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Due to direct interaction of radiation with key molecules within the microbial cell, as well as inhibitory effect of free radicals (H+, OH- ions) produced by radiolysis of water.
16. How does radiation resistance vary among microorganisms?
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Gram-negative bacteria are more sensitive than Gram-positive, followed by spores. Many spoilage bacteria of seafoods are Gram-negative, hence least resistant to irradiation. E. coli is highly sensitive and not useful as an indicator.
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