Food Microbiology Questions and Answers – Food Preservation – Modification of Atmosphere and Water Activity Control

This set of Food Microbiology Multiple Choice Questions & Answers (MCQs) focuses on “Food Preservation – Modification of Atmosphere and Water Activity Control”.

1. Low pressure storage is called _______ storage.
a) Hyperbaric
b) Hyperchoric
c) Hypobaric
d) Hypochoric
View Answer

Answer: c
Explanation: Low pressure storage results in reduced concentrations of oxygen. This in turn results in reduced fat oxidation. This can extend the life of fruits and vegetables. This causes low respiration rate and evacuation of ethylene.

2. The inhibitory activity of carbon dioxide _______ as the storage temperature decreases.
a) Increases
b) Decreases
c) Remains constant
d) Stops
View Answer

Answer: a
Explanation: Carbon dioxide is more soluble in water at lower temperatures. As the temperature increases, the kinetic energy increases. This causes the gas molecules to break free and escape. Hence, gases are more soluble at low temperatures. This increases the inhibitory activity.

3. Who developed the method of preserving food using boiling water?
a) Francois Nicolas Appert
b) Charles Mitchell
c) Peter Durand
d) Louis Pasteur
View Answer

Answer: a
Explanation: Francois Nicolas Appert introduced methods to preserve food using the heat from boiling water. Peter Durand is credited with the development of the steel canning method. Charles Mitchell incorporated the metal lining inside the cans to improve the quality and efficiency of food preservation. Pasteur introduced heating of wine to destroy souring bacteria.

4. Which of the following techniques uses the method of reduction in water activity?
a) Curing
b) Emulsification
c) Blanching
d) Radicidation
View Answer

Answer: a
Explanation: Curing reduces water activity so as to delay or prevent the growth of microbes. Emulsification uses the method of compartmentalization whereas blanching expels the oxygen from the tissues. Radicidation uses radiation.

5. The lowering of water activity can lead to a longer lag phase and a shorter growth phase.
a) True
b) False
View Answer

Answer: a
Explanation: All chemical and biological reactions need an aqueous environment. If the water activity i.e. the amount of water required for the functioning of cells is reduced, the growth will be adversely affected. Also, the size of the final population will decrease. The drying of the internal components of the cell may take place and the fluidity of the cell membrane is not maintained.

6. Which of the following is not used to reduce water activity?
a) Honey
b) Millets
c) Salt
d) Starch
View Answer

Answer: b
Explanation: Substances like honey, salt and starch bind to the water. This reduces the water activity and helps in food preservation.

7. What is the full form of IMF?
a) Intermediate Moisture Foods
b) Inner Moisture Foods
c) Inane Moisture Foods
d) Inconspicuous Moisture Foods
View Answer

Answer: a
Explanation: Intermediate Moisture Foods are those that have water activity between 0.85 and 0.6. This inhibits the growth of Gram-negative bacteria.

8. Sweetened condensed milk has a gritty texture because of _________
a) Casein
b) Crystalline sugar
c) Glucose crystals
d) Lactose crystals
View Answer

Answer: d
Explanation: Milk is homogenized, heated and then cooled with the addition of sugar to make condensed milk. Later, it is seeded with lactose crystals. The long shelf-life of this is due to its low water activity and high sugar content.

9. ___________ is not a novel humectant.
a) Glycerol
b) Methanol
c) Sorbitol
d) Propylene glycol
View Answer

Answer: b
Explanation: Glycerol, sorbitol and propylene glycol are used as novel humectants to adjust the water activity in food. Methanol is a poisonous compound.

Sanfoundry Global Education & Learning Series – Food Microbiology.

To practice all areas of Food Microbiology, here is complete set of Multiple Choice Questions and Answers.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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