This set of Food Processing Unit Operations Multiple Choice Questions & Answers (MCQs) focuses on “Heat Transfer Applications – Chilling and Freezing”.
1. Who invented chillers?
a) Louis Pasteur
b) Charles Chamberland
c) Willis Carrier
d) Clarence Birdseye
View Answer
Explanation: The pasteurization process was developed by Louis Pasteur. Charles Chamberland developed the first pressure steam sterilizer. Willis Carrier invented the chillers. Clarence Birdseye developed processes for freezing fish based on quick freezing.
2. _________ is used for cooling of products, mechanisms and factory machinery under control temperature.
a) Chiller
b) Ice
c) Alcohol
d) Ice or alcohol according to the product
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Explanation: Chillers are used for cooling of products, mechanisms and factory machinery under control temperature. These follow absorption refrigerant cycle or vapor compressionfor cooling a fluid. The basic principle is that heat always flows from hot to cold.
3. What is the ideal chilled water temperature?
a) 42°F
b) 52°F
c) 49°F
d) 50°F
View Answer
Explanation: 42°F is the ideal chilled water temperature. The temperature of chilled water can range from 35 to 45 °F (2 to 7 °C), depending upon requirements.
4. __________ invented the quick freezing method in 1924.
a) Clarence Birdseye
b) Charles Chamberland
c) Willis Carrier
d) Clarence Birdseye
View Answer
Explanation: Clarence Birdseye invented the quick freezing method. Charles Chamberland developed the first pressure steam sterilizer. Willis Carrier invented the chillers. Clarence Birdseye developed processes for freezing fish based on quick freezing.
5. ______ chillers are also called as centrifugal chiller type refrigeration systems.
a) Low-pressure
b) Low-temperature
c) Low-velocity
d) High-pressure
View Answer
Explanation: Low-pressure chillers are also called as centrifugal chiller type refrigeration systems. It works under vacuum in the evaporator section of the system. If there is any leaks in the low pressure portions of the system, it will draw in the atmospheric air and moisture from the surroundings.
6. ________ chiller is powered by a heat source like steam and uses no moving parts.
a) Absorption
b) Reciprocating
c) Centrifugal
d) Screw driven
View Answer
Explanation: In absorption chillers, the refrigerant is absorbed by a liquid sorbent. The refrigerant used are water and ammonia and liquid sorbents arelithium bromide or water. At high temperatures, the refrigerant is desorbed from solution.
7. ________ chillers are volume displacement units.
a) Absorption
b) Reciprocating
c) Centrifugal
d) Screw driven
View Answer
Explanation: Centrifugal chillers are volume displacement units. The advantages are compact size, high operational efficiency at full load. It is not suitable for air cooled condenser options and requires cooling water tower and water.
8. Freezer burn is a condition that occurs when frozen food has been damaged by ___________
a) dehydration
b) oxidation
c) dehydration and oxidation
d) dehydration and reduction
View Answer
Explanation: Freezer burn occurs when frozen food is damaged by dehydration and oxidation. It is normally due to improper of storage of food. Therefore, it should be securely wrapped in air-tight packaging to prevent oxidation and dehydration. The food appears grayish brown leathery spots on the frozen foods.
9. _______ is used to freeze particulate foods like peas, cut corn.
a) Fluidized bed freezer
b) Plate freezer
c) Cryogenic freezers
d) Belt freezer
View Answer
Explanation: Fluidized bed freezer is used to freeze particulate foods like peas, cut corn. The foods are placed on a mesh and moved through a freezing zone where cold air in upward direction is directed through the mesh belt and the food particulates begin to float. This leads to uniform freezing in all directions.
10. _______ is used to freeze food at a tremendously fast rate.
a) Fluidized bed freezer
b) Plate freezer
c) Cryogenic freezers
d) Belt freezer
View Answer
Explanation: Cryogenic freezing is used to freeze food at a tremendously fast rate. The food is moved through a spray of liquid nitrogen. It can also be directly immersed in liquid nitrogen. The liquid nitrogen boils at a temperature of −196 °C around the food and thus extracts a huge amount of heat at faster pace.
Sanfoundry Global Education & Learning Series – Food Processing Unit Operations.
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