This set of Vegetables Processing Multiple Choice Questions & Answers (MCQs) focuses on “Refrigeration and Freezing Preservation of Vegetables”.
1. Which of the following preservation technique is used for preserving the food in its original position?
a) Refrigeration
b) Drying
c) Spray drying
d) Refrigeration and drying
View Answer
Explanation: The Refrigeration is the only means of preserving food in its original position. The preservation of perishable foods by refrigeration involves the use of low temperature. it is one of the means of eliminating the activity of spoilage agents.
2. How many days can food be stored in cold storage?
a) 1 day
b) Up to 15 days
c) Up to 30 days
d) Up to 365 days
View Answer
Explanation: Many food products may be stored at some temperature above freezing point. The storages which are used for short term storage purposes are known as cold storages. The period for short term storage ranges from one to two days or to a week or more in some cases, but not more than 15 days under any circumstances.
3. What is the role of solid carbon dioxide in cryogenic chillers?
a) Removes latent heat of sublimation
b) Removes latent heat of vaporization
c) Removes latent heat of fusion
d) Removes latent heat
View Answer
Explanation: Cryogenic chillers use solid carbon dioxide, liquid carbon dioxide and liquid nitrogen. Solid carbon dioxide removes latent heat of sublimation. The latent heat of sublimation at a particular temperature is the amount of heat required to convert a unit mass of solid into gas.
4. What is the role of liquid cryogens in cryogenic chillers?
a) Removes latent heat of sublimation
b) Removes latent heat of vaporization
c) Removes latent heat of fusion
d) Removes latent heat
View Answer
Explanation: liquid cryogens remove latent heat of vaporization. Latent heat of vaporization is a physical property of a substance. It is defined as the heat required changing one mole of liquid at its boiling point under standard atmospheric pressure.
5. What is the most significant effect of chilling?
a) Solidification of fats
b) Solidification of proteins
c) Denaturation of proteins
d) Denaturation of fats
View Answer
Explanation: The most significant effect of chilling on the sensory characteristics of processed foods is hardening due to solidification of fats and oils. Other effects include enzymatic browning, lipolysis. The color and flavor deterioration can take place in some products.
6. What is the temperature of super chilling?
a) -1 to -4°C
b) -15 to -40°C
c) 1 to 4°C
d) 0°C
View Answer
Explanation: Super chilling is one of the methods that can be used to maintain food products at a low temperature. Generally, super chilling is positioned between freezing and refrigeration. It is a process by which the temperature of a food product is lowered to -1 to -4°C.
7. What is the significance of super chilling?
a) Ice crystals are not formed
b) Small ice crystals are formed
c) Large ice crystals are formed
d) Both small and large ice crystals are formed
View Answer
Explanation: Super chilling is that where temperature of food is maintained below 0°C but ice crystals are not generated. It is defined as a technology where food is stored just below the initial freezing temperature. It increases the shelf life of the product.
8. Freezing is not a unit operation.
a) True
b) False
View Answer
Explanation: Freezing is the unit operation in which the temperature of a food is reduced below its freezing point. A proportion of the water in the product undergoes a change in state to form ice crystals. It is a combination of low temperature at which micro-organisms cannot grow, chemical changes are reduced and cellular metabolic reactions are delayed.
9. Which heat is removed initially to lower the temperature of the product during freezing?
a) Sensible heat
b) Field heat
c) Latent heat
d) Both sensible and latent heat
View Answer
Explanation: Sensible heat is first removed to lower the temperature of food to the freezing point. Heat produced by respiration in case of fresh foods (fruits and vegetables) is also removed. Sensible heat is the energy required to change the temperature of a substance with no phase change.
10. Which heat is removed in freezing to produce ice crystals?
a) Latent heat of sublimation
b) Latent heat of vaporization
c) Latent heat of fusion
d) Latent heat of crystallization
View Answer
Explanation: The latent heat of crystallization is removed to form ice crystals. The latent heat of crystallization of other components of food like fats is also removed. The fractional latent heat of a crystallizing system is simply the latent heat of fusion divided by the total enthalpy.
11. How does individually quick-frozen (IQF) freezer work?
a) Does not allow large ice crystals to form in cells
b) Does not allow small ice crystals to form in cells
c) Does not allow large ice crystals to form in mitochondria
d) Does not allow small ice crystals to form in mitochondria
View Answer
Explanation: An individually quick-frozen (IQF) method is mainly used for storing fresh vegetables. It is a method which does not allow formation of large ice crystals in vegetable cells. Since each piece is separately frozen, it does not adhere and the final product is not frozen into the solid block.
12. Freezer burn is caused by sublimation of ice.
a) True
b) False
View Answer
Explanation: Freezer Burn is caused by sublimation of ice from the surface of food into the air inside the freezer. The surface of freezer burned food appears as dry, grainy and brownish spots. The tissues become dry and tough.
Sanfoundry Global Education & Learning Series – Vegetables Processing.
To practice all areas of Vegetables Processing, here is complete set of 1000+ Multiple Choice Questions and Answers.
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