# Food Processing Unit Operations Questions and Answers – Size Reduction Theory

This set of Food Processing Unit Operations Multiple Choice Questions & Answers (MCQs) focuses on “Size Reduction Theory ”.

1. What are the size reduction laws?
a) Rittinger’s Law
b) Kick’s Law
c) Bond’s Law
d) Bond’s Law, Rittinger’s Law, and Kick’s Law

Explanation: There are three physical laws that describe the energy required for size reduction. They are the Bond’s Law, Rittinger’s Law, and Kick’s Law. The size reduction is a unit operation where a set of conditions are performed until the size specified is achieved.

2. Which mechanism is utilized when particle concussion by a single rigid force?
a) Impact
b) Compression
c) Shear
d) Tear

Explanation: In impact force mechanism, the particle concussion by a single rigid force where usually hammer is used to create such force. It is a force that provides a shock in a relatively short period of time.

3. What is the mechanism of nut cracker?
a) Impact
b) Compression
c) Shear
d) Tear

Explanation: In the compression force the particle are disintegrated by two rigid forces. The nutcracker is based on this mechanism. Compression Force is the uses the power, exertion and pressure against an object which results in squeezing, squashing.

4. What is shear force?
a) Force acting in direction parallel to surface of a body
b) Force acting in direction perpendicular to surface of a body
c) Force acting in direction longitudinal to surface of a body
d) Force acting in direction vertical to surface of a body

Explanation: Shear force is the force acting in direction parallel to surface of a body, it is produced when the particle is compressed between the edges of two hard surfaces moving tangentially.

5. Why is uniform particle size important?
a) Color improvement
b) Product stability
c) Flavor improvement
d) Color and flavor improvement

Explanation: Size reduction is defined as the adding the energy to a material to make large pieces smaller. Particle size is important for product stability. It is achieves a quality end product.

6. Which of the following is a size reduction unit operation in liquids?
a) Milling
b) Mixing
c) Grinding
d) Homogenization

Explanation: Homogenization is a size reduction unit operation in liquids. It is used to produce a mixture of two mutually non-soluble liquids into homogenized solution.

7. What are the factors affecting size reduction?
a) Shape and size
b) Temperature
c) Pressure
d) Viscosity

Explanation: Shape and size are the two important factors that affect size reduction unit operation. Size reduction is a process in which the particle size of a solid is made smaller and is applied in which particles of solids are made into smaller pieces.

8. What is a hammer mill used for?
a) Crush larger pieces into small pieces
b) To compress the raw materials
c) Break down of liquefied emulsions
d) Break smaller pieces into fine powder

Explanation: A hammer mill is a mill which is used to shred or crush larger material into smaller pieces by the repeated blows of little hammers. It creates impact force.

9. What is size reduction equipment?
a) Adding energy to a material to make large pieces smaller
b) Removing energy to a material to make large pieces smaller
c) Adding energy to a material to make small pieces larger
d) Removing energy to a material to make small pieces larger

Explanation: The size reduction is a unit operation where a set of conditions are performed until the size specified is achieved. It is based on the adding of the energy to a material which in turn produces smaller pieces from large pieces.

10. What is use of edge runner?
a) To crush the pieces
b) To compress the pieces
c) To tear the pieces
d) To shear the pieces

Explanation: Edge runner is a machine consisting of heavy steel rolls set on a horizontal shaft rotating round a pan that is used for crushing stone, fibrous matter for paper making or other material.

Sanfoundry Global Education & Learning Series – Food Processing Unit Operations.

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