Thermal operations - Food Engineering - Life Sciences Previous Year Questions

1

2011 · Life Sciences · Food Engineering · Thermal operations

Life Sciences (XL) 2011

The F – value at 121.1 °C, equivalent to 99.9999 percent destruction of a strain of Clostridium botulinum, is 1.8 min. The D₀ value (decimal reduction time at reference temperature) of the organism will be

A

10.8 min

B

0.3 min

C

6.0 min

D

0.2 min

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2

2013 · Life Sciences · Food Engineering · Thermal operations

Life Sciences (XL) 2013

Thermal death of viable spores of Bacillus subtilis in a food sample follows a first order kinetics with a specific death rate constant of 0.23 min⁻¹ at 100°C. The time (in minutes) required to kill 99% of spores in the food sample at 100°C will be

A

10

B

20

C

23

D

60

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3

2014 · Life Sciences · Food Engineering · Thermal operations

Life Sciences (XL) 2014

One ton of refrigeration means one of the following options:

A

Cooling provided by one kg of ice in one hour

B

Cooling provided by one ton of ice in one hour

C

Energy extracted to freeze one ton of water in one day

D

Coefficient of performance is unity

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4

2019 · Life Sciences · Food Engineering · Thermal operations

Life Sciences (XL) 2019

Sticking of powder to wall of the chamber during spray drying of fruit juice is due to ____.

A

Low glass transition temperature of the compounds in juice

B

High glass transition temperature of the compounds in juice

C

Improper processing parameters of spray dryer

D

Presence of gums in feed material

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5

2020 · Life Sciences · Food Engineering · Thermal operations

Life Sciences (XL) 2020

Match the equation/law in Column I with its application in Column II.

Column I	Column II
P. Plank's equation	1. Terminal velocity
Q. Arrhenius equation	2. Freezing time
R. Guggenheim-Anderson-de Boer equation	3. Activation energy
S. Stoke's law	4. Monolayer moisture content

A

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

B

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

C

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

D

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

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6

2020 · Life Sciences · Food Engineering · Thermal operations

Life Sciences (XL) 2020

During extrusion cooking, food materials are generally subjected to a combination of

A

high shear and low pressure

B

high temperature and high shear

C

low shear and high temperature

D

low shear and low pressure

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7

2022 · Life Sciences · Food Engineering · Thermal operations

Life Sciences (XL) 2022

Which among the given options truly depict the lines 1 and 2 in the figure below with respect to the effect of heat processing on food?

A

1-Safety, 2-Quality

B

1-Yield, 2-Safety

C

1-Yield, 2-Quality

D

1-Quality, 2-Safety

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8

2022 · Life Sciences · Food Engineering · Thermal operations

Life Sciences (XL) 2022

In a canning industry, the total process time (F₀) was calculated as 3 min. If each can contains 20 spores having decimal reduction time of 1.6 min, the probability of spoilage would be ______ in 100 cans (round off to the nearest integer).

Check answer

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9

2022 · Life Sciences · Food Engineering · Thermal operations

Life Sciences (XL) 2022

Most commonly used refrigerant in direct immersion freezing of food is

A

Monochlorodifluoromethane

B

Dichlorodifluoromethane

C

Liquid nitrogen

D

Freon

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10

2025 · Life Sciences · Food Engineering · Thermal operations

Life Sciences (XL) 2025

In canning and retorting of foods, which of the following is the correct expression of Ball process time (B)?
Assume: t_p = processor’s process time; t_c = come-up time

A

B = t_p + 0.42 t_c

B

B = t_p + 0.30 t_c

C

B = t_p + 0.50 t_c

D

B = t_p + 0.25 t_c

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