This set of Food Microbiology Multiple Choice Questions & Answers (MCQs) focuses on “Food Preservation – Irradiation and Pascalization”.
1. The unit of measure used to express an exposure dose of gamma radiation is called __________
a) Curie
b) Rad
c) Roentgen
d) Becquerel
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Explanation: A Curie is the amount of substance in which certain number of disintegrations occur per second. The unit for a curie is Becquerel. The unit to measure the exposure dose of radiation is called a Roentgen.
2. UV rays kill microbes by acting on the ________
a) Nucleus
b) Cytoplasm
c) Vacuoles
d) Mitochondria
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Explanation: The UV rays act on the nucleic material and cause damage in the form of mutations. They can also cleave the DNA.
3. Gamma radiation is the cheapest form of radiation.
a) True
b) False
View Answer
Explanation: The sources of gamma radiation are either by-products of atomic fission or atomic waste products. Hence, it is cheap.
4. _______ causes damage to DNA during radiation.
a) Hydrogen
b) Hydroxyl radicle
c) Nitrites
d) Carbon dioxide
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Explanation: Reactive Oxygen Species (ROS) such as hydroxyl radicles and superoxide anions are produced when the microbes are exposed to radiation. Different microbes have different capacities to produce these and hence their sensitivity differs. These species cause DNA damage and cell death.
5. Commercial sterility is obtained by ___________
a) Lethal dosing
b) Radurization
c) Radicidation
d) Radappertization
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Explanation: Radappertization is the same as radiation sterilization. It requires the proper dose of radiation under proper conditions.
6. The best option for the removal of non-spore forming bacteria is _________
a) Lethal dosing
b) Radurization
c) Radicidation
d) Radappertization
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Explanation: Radicidation can kill non-spore forming bacteria as well as non-viral pathogens without harming humans. It kills specific viable bacteria to a certain level at which they cannot be detected by any known method.
7. ________ can be used to extend shelf life for a very long time.
a) Lethal dosing
b) Radurization
c) Radicidation
d) Radappertization
View Answer
Explanation: Radurization is usually used to extend the shelf life of seafood. This is done with the help of high power radiation. This usually consists of doses of mild ionizing radiation to eliminate or reduce microbes.
8. _______ is most susceptible to electron beam radiation.
a) Alanine
b) Cysteine
c) Valine
d) Glutamine
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Explanation: It was found that 50% of cysteine was lost after irradiation with electron beams. 10% of tryptophan was lost, whereas other amino acids were fine.
9. Pascalization is done using _______
a) Low Pressure
b) Low Temperature
c) High Pressure
d) High Temperature
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Explanation: High Pressure Processing is used to reduce or eliminate microbes in food. This method uses hydrostatic pressure to do the same.
10. _______________ in orange juice should be inactivated.
a) Pectin Esterase
b) Pectin Lyase
c) Pectin Hydrolase
d) Pectin Maltase
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Explanation: Pectin esterase is an enzyme associated with the plant cell wall. It alters the cell wall integrity by altering the local pH. When pectin esterase is inactivated, it gives us the stable desired cloudiness.
11. Flavor is unaffected in HPP.
a) True
b) False
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Explanation: Hydrostatic pressures are non-thermal and covalent bonds are not cleaved. This preserves the taste of the food. The chemical integrity of the food is preserved due to no evolution of high temperature. Hence, the flavor remains unaffected.
12. Gram-positive bacteria are more resistant to pressure than Gram-negative bacteria.
a) True
b) False
View Answer
Explanation: Gram-negative bacteria have a thinner outer wall as compared to Gram-positive bacteria. Thicker peptidoglycan walls provide more resistance.
Sanfoundry Global Education & Learning Series – Food Microbiology.
To practice all areas of Food Microbiology, here is complete set of Multiple Choice Questions and Answers.
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