Mechanical Operations - Food Engineering - Engineering Sciences Previous Year Questions

1

2008 · Engineering Sciences · Food Engineering · Mechanical Operations

Engineering Sciences (XE) 2008

In modern rice mills, the two rubber rolls in the sheller rotate in opposite direction at the

A

same rotational speed and different surface speed

B

same rotational speed and same surface speed

C

different rotational speed and different surface speed

D

different rotational speed and same surface speed

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2

2009 · Engineering Sciences · Food Engineering · Mechanical Operations

Engineering Sciences (XE) 2009

A cyclone separator is used for the separation of

A

particles from liquid

B

liquid droplets from gas

C

fine particles from gas

D

fine particles from solids

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3

2012 · Engineering Sciences · Food Engineering · Mechanical Operations

Engineering Sciences (XE) 2012

Make the correct match between specific food processing operations in Group I with their mechanism of action in Group II.
Group I
P) Ball Mill
Q) Roller Mill
R) Flash Peeling
S) Abrasive Peeling

Group II
1) Compression and shear
2) Pressure bursting
3) Friction and shear
4) Impact and shear

A

P-4, Q-2, R-1, S-3

B

P-4, Q-1, R-2, S-3

C

P-4, Q-3, R-2, S-1

D

P-3, Q-1, R-4, S-2

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4

2014 · Engineering Sciences · Food Engineering · Mechanical Operations

Engineering Sciences (XE) 2014

The energy required to reduce the size of a food material from a mean diameter of 12 mm to 4 mm is 10 kJ kg\(^{-1}\). From Rittinger’s law, the energy needed to reduce the same material from a diameter of 1.2 mm to 0.4 mm in kJ kg\(^{-1}\) is ______________

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5

2014 · Engineering Sciences · Food Engineering · Mechanical Operations

Engineering Sciences (XE) 2014

Make the correct combination of operations in Column I with the machines in Column II

Column I	Column II
1) Rice milling	P) Pin mill
2) Wheat milling	Q) Rubber rolls
3) Mustard oil expelling	R) Break rolls
4) Pepper grinding	S) Screw press

A

1-Q, 2-R, 3-S, 4-P

B

1-R, 2- Q, 3-S, 4-P

C

1-Q, 2-P, 3-S, 4-R

D

1-Q, 2-R, 3- P, 4- S

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6

2015 · Engineering Sciences · Food Engineering · Mechanical Operations

Engineering Sciences (XE) 2015

How many fold would the g-number of a centrifuge increase by doubling both the spinning speed and bowl diameter?

A

2

B

4

C

8

D

16

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7

2015 · Engineering Sciences · Food Engineering · Mechanical Operations

Engineering Sciences (XE) 2015

Granulated sugar, having an average particle size of 500 μm, is milled to produce icing sugar having an average particle size of 25 μm. The power requirement was 10 kW as obtained by Rittinger’s law. If the same mill were to be used to produce fondant sugar having an average particle size of 20 μm at the same capacity, the power requirement (kW) would be ______

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8

2016 · Engineering Sciences · Food Engineering · Mechanical Operations

Engineering Sciences (XE) 2016

The rate of cream separation in a disc bowl centrifuge can be increased by _____.

A

Increasing the size of the bowl

B

Lower viscosity of fluid

C

Increasing RPM of the bowl

D

All of these

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9

2016 · Engineering Sciences · Food Engineering · Mechanical Operations

Engineering Sciences (XE) 2016

In an aeration system, 520 kg of wheat grains having average size of 0.15 mm, shape factor of 0.88 and density of 1040 kg m^-3 are fluidized using air at 2 atm absolute and 25 °C. If the cross section of empty bed is 0.4 m², the minimum height (m) of the fluidized bed, with voidage of 0.45 will be ______.

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10

2018 · Engineering Sciences · Food Engineering · Mechanical Operations

Engineering Sciences (XE) 2018

Match the operation in Group I with the process in Group II.
Group I
P. Cleaning
Q. Grading
R. Size reduction
S. Filtration
Group II
1. Quality separation
2. Clarification
3. Screening
4. Comminution

A

P-1, Q-3, R-4, S-2

B

P-4, Q-1, R-3, S-2

C

P-2, Q-4, R-1, S-3

D

P-3, Q-1, R-4, S-2

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11

2018 · Engineering Sciences · Food Engineering · Mechanical Operations

Engineering Sciences (XE) 2018

Black pepper is ground from an equivalent particle size of 6 mm to 0.12 mm using a 10 hp motor. Assuming Rittinger's equation and that 1 hp = 745.7 W, the power (hp) of motor required to fine grind black pepper to 0.08 mm would be ______. (up to two decimal points)

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12

2020 · Engineering Sciences · Food Engineering · Mechanical Operations

Engineering Sciences (XE) 2020

Match the component/system in Column I with the peeling method for fruits and vegetables in Column II.

A

P-4, Q-3, R-2, S-1

B

P-3, Q-4, R-1, S-2

C

P-4, Q-3, R-1, S-2

D

P-3, Q-4, R-2, S-1

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13

2020 · Engineering Sciences · Food Engineering · Mechanical Operations

Engineering Sciences (XE) 2020

The velocity of 2.2 μm diameter fat particles inside a centrifuge, running at 6000 rpm and 20 °C, is 0.25 mm s⁻¹. The velocity of 1.5 μm diameter fat particles inside the same centrifuge running at 7500 rpm and same temperature (round off to 2 decimal places) will be ______ mm s⁻¹.

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14

2022 · Engineering Sciences · Food Engineering · Mechanical Operations

Engineering Sciences (XE) 2022

Homogenization of milk leads to disintegration of fat globules by

A

Turbulence and pasteurization

B

Pasteurization and cavitation

C

Pasteurization and pressurization

D

Turbulence and cavitation

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15

2022 · Engineering Sciences · Food Engineering · Mechanical Operations

Engineering Sciences (XE) 2022

Identify the correct pair(s) of milling equipment and the grain for which it is used.

A

Mist polisher–Rice

B

Break roll–Wheat

C

Rubber roll–Pigeon pea

D

Beall degermer–Maize

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16

2022 · Engineering Sciences · Food Engineering · Mechanical Operations

Engineering Sciences (XE) 2022

Match the size reduction equipment in Column I with the method of operation in Column II.
Column I: P. Hammer mill, Q. Burr mill, R. Crushing rolls, S. Rotary knife
Column II: 1. Compression, 2. Impact, 3. Cutting, 4. Attrition

A

P-2, Q-4, R-1, S-3

B

P-3, Q-1, R-2, S-4

C

P-4, Q-1, R-2, S-3

D

P-3, Q-4, R-2, S-1

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17

2022 · Engineering Sciences · Food Engineering · Mechanical Operations

Engineering Sciences (XE) 2022

In sieve analysis of coffee powder, the particle size distribution is given below

Number of particles	Mean particle size (μm)
5	40
8	30
50	20
90	17.5
148	12.5
10	10

The Sauter mean diameter (in μm) of the coffee powder is ______ (round off to one decimal place).

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18

2023 · Engineering Sciences · Food Engineering · Mechanical Operations

Engineering Sciences (XE) 2023

A hammer mill is used to grind blackgram. The size distribution of the blackgram is such that 80% passes through a 6-mesh (particle size = 3.36 mm) screen. The power requirement to produce a powder, 80% of which passes through a 45-mesh (particle size = 0.354 mm) screen is 4.5 kW. The power in kW required to produce a finer powder 80% of which passes through a 60-mesh (particle size = 0.25 mm) will be ______ (rounded off to 2 decimal places). Assume the feed rate to the mill is constant in both the cases. Use Bond’s law of size reduction.

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19

2024 · Engineering Sciences · Food Engineering · Mechanical Operations

Engineering Sciences (XE) 2024

Which of the following statements is/ are true?

A

Hagen-Poiseuille's law is used for calculation of molecular diffusion.

B

Fick's law is used for calculation of energy requirement in size reduction.

C

Rittinger's law is used for calculation of energy requirement in size reduction.

D

Stokes law is used for derivation of terminal velocity.

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20

2026 · Engineering Sciences · Food Engineering · Mechanical Operations

Engineering Sciences (XE) 2026

Which one of the following statements is true for a high-pressure homogenizer?

A

Homogenization takes place only due to uniform mixing of solid and liquid

B

Solid particles in the suspension are disintegrated due to the high shear rate exerted by the liquid

C

High pressure steam is injected to dissolve the solids

D

Solid particles in the suspension are compressed into a cake under high pressure

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