Thermal and Non-Thermal Food Preservation Technology
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Question No. 1
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What is the temperature range used in
HTST pasteurization
of milk?
A.
135°C for 2 seconds
B.
72°C for 15 seconds
C.
63°C for 30 minutes
D.
100°C for 10 minutes
Question No. 2
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Which thermal process achieves
commercial sterility
by eliminating all microorganisms including spores?
A.
Blanching
B.
LTLT pasteurization
C.
Sterilization
D.
Refrigeration
Question No. 3
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The primary purpose of
blanching
vegetables before freezing is to:
A.
Increase moisture content
B.
Inactivate enzymes
C.
Add preservatives
D.
Add flavor
Question No. 4
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What does
UHT processing
stand for in thermal food preservation?
A.
Ultra-High Temperature
B.
Universal Heating Technology
C.
Uniform Heat Treatment
D.
Under Heat Transfer
Question No. 5
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In
retort sterilization
, sealed food containers are subjected to:
A.
High pressure without heat
B.
Pressurized steam at high temperature
C.
Ultraviolet light
D.
Cold air circulation
Question No. 6
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Which thermal method is most suitable for
shelf-stable milk
that requires no refrigeration?
A.
Refrigeration only
B.
Blanching
C.
LTLT pasteurization
D.
UHT processing
Question No. 7
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The main advantage of
ohmic heating
over conventional heating is:
A.
It only works for solid foods
B.
Uniform and rapid heating throughout the food
C.
It uses cold temperatures
D.
It requires no electricity
Question No. 8
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In
microwave heating
, food is heated by:
A.
Chemical reactions
B.
Conduction from hot surfaces
C.
Electromagnetic waves causing molecular vibration
D.
Infrared radiation only
Question No. 9
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What is the typical temperature range for
LTLT pasteurization
?
A.
50°C for 1 hour
B.
100°C for 1 minute
C.
135°C for 2 seconds
D.
63°C for 30 minutes
Question No. 10
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Which statement about
thermal sterilization
is correct?
A.
It is the same as pasteurization
B.
It preserves all heat-sensitive vitamins
C.
It operates below 100°C
D.
It eliminates all microorganisms including spores
Question No. 11
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The principle behind
infrared heating
in food processing is:
A.
Direct absorption of infrared radiation by food molecules
B.
Chemical transformation
C.
Cooling through radiation
D.
High pressure application
Question No. 12
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A major disadvantage of conventional
thermal processing
is:
A.
It preserves all nutrients
B.
It is too cheap
C.
Loss of heat-sensitive nutrients and altered sensory properties
D.
It cannot kill bacteria
Question No. 13
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In
radio frequency heating
, what frequency range is typically used?
A.
Above 500 GHz
B.
1-300 MHz
C.
Below 1 kHz
D.
300 MHz to 300 GHz
Question No. 14
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What is the primary target of
pasteurization
?
A.
Pathogenic non-spore-forming bacteria
B.
Only molds
C.
Only viruses
D.
All microorganisms including spores
Question No. 15
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The
D-value
in thermal processing represents the time required to:
A.
Double the microbial population
B.
Reduce microbial population by 90%
C.
Heat food to desired temperature
D.
Cool food completely
Question No. 16
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What does
HPP
stand for in non-thermal food preservation?
A.
Hot Pasteurization Process
B.
High Pressure Processing
C.
Heat Processing Procedure
D.
Hydrogen Peroxide Preservation
Question No. 17
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In
High Pressure Processing (HPP)
, typical pressure ranges are:
A.
50-100 MPa
B.
1-10 MPa
C.
1000-2000 MPa
D.
400-600 MPa
Question No. 18
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The mechanism of microbial inactivation in
Pulsed Electric Field (PEF)
technology involves:
A.
Freezing cells
B.
Chemical reactions
C.
Heating to high temperatures
D.
Electroporation of cell membranes
Question No. 19
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Which wavelength range of
UV radiation
is most effective for food preservation?
A.
UV-D (above 400 nm)
B.
UV-B (280-315 nm)
C.
UV-A (315-400 nm)
D.
UV-C (200-280 nm)
Question No. 20
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Food
irradiation
uses which types of ionizing radiation?
A.
Microwaves
B.
Gamma rays, X-rays, or electron beams
C.
Only visible light
D.
UV light only
Question No. 21
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A key advantage of
non-thermal preservation
technologies over thermal methods is:
A.
They are always cheaper
B.
They work faster
C.
Better retention of nutrients and sensory properties
D.
They require no equipment
Question No. 22
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In
cold plasma
technology, microbial inactivation is achieved through:
A.
High temperature only
B.
High pressure
C.
Reactive species, UV radiation, and charged particles
D.
Freezing
Question No. 23
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What is the primary limitation of
UV light
in food preservation?
A.
It increases temperature excessively
B.
It is too expensive
C.
It changes food color
D.
Limited penetration depth
Question No. 24
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Which non-thermal technology is also called
pascalization
?
A.
Irradiation
B.
High Pressure Processing
C.
Pulsed Electric Field
D.
Ultrasonication
Question No. 25
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In
ultrasound
food processing, microbial inactivation occurs due to:
A.
Only heating
B.
Freezing
C.
Cavitation creating shock waves and free radicals
D.
Chemical additives
Question No. 26
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What is the main concern regarding consumer acceptance of
food irradiation
?
A.
It changes all nutrients
B.
It makes food too expensive
C.
Misconception that food becomes radioactive
D.
It makes food taste bitter
Question No. 27
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Which statement about
Pulsed Electric Field (PEF)
is correct?
A.
It requires temperatures above 100°C
B.
It applies short high-voltage pulses
C.
It works only on solid foods
D.
It uses continuous electric current
Question No. 28
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The unit of measurement for radiation dose in food irradiation is:
A.
Degrees Celsius
B.
Gray (Gy) or kiloGray (kGy)
C.
Pascal
D.
Watt
Question No. 29
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Which non-thermal technology is most effective for treating
liquid foods
with particulates?
A.
Irradiation
B.
UV radiation
C.
High Pressure Processing
D.
Pulsed Electric Field
Question No. 30
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Pulsed light
technology uses intense pulses of:
A.
Only X-rays
B.
Only visible light
C.
Only infrared light
D.
Broad-spectrum white light including UV
Question No. 31
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What is a major advantage of
HPP
for fruit juices?
A.
It concentrates the juice
B.
Removes all water
C.
Maintains fresh flavor and color while ensuring safety
D.
Adds vitamins
Question No. 32
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The antimicrobial effect of
ozone
in food preservation is due to its:
A.
Ability to lower pH
B.
Cooling effect
C.
Addition of salt
D.
Strong oxidizing properties
Question No. 33
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Which factor does
NOT
affect the efficacy of HPP treatment?
A.
Type of microorganism
B.
Color of packaging material
C.
Pressure level
D.
Treatment time
Question No. 34
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In
membrane filtration
for milk, which process removes bacteria?
A.
Electrodialysis
B.
Microfiltration
C.
Reverse osmosis
D.
Dialysis
Question No. 35
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What is the typical frequency used in
ultrasound
food processing?
A.
Above 20 kHz
B.
20 Hz to 20 kHz
C.
Below 20 Hz
D.
Above 300 GHz
Question No. 36
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The main advantage of
cold plasma
over traditional chemical sanitizers is:
A.
No chemical residues and rapid treatment
B.
It requires high temperature
C.
It works only in liquids
D.
It is always cheaper
Question No. 37
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Which statement about
food irradiation
is FALSE?
A.
It can extend shelf life
B.
It makes food radioactive
C.
It is approved by WHO and FAO
D.
It can kill insects in grains
Question No. 38
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In
ohmic heating
, the rate of heat generation depends primarily on:
A.
Electrical conductivity of food
B.
Room temperature
C.
Color of food
D.
Packaging type
Question No. 39
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What is
hurdle technology
in food preservation?
A.
Only thermal processing
B.
Combining multiple preservation techniques
C.
Storing at room temperature
D.
Using only one preservation method
Question No. 40
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Which non-thermal technology is most established commercially and widely accepted?
A.
Ozone treatment
B.
Pulsed light
C.
High Pressure Processing
D.
Cold plasma
Question No. 41
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The penetration of
microwave energy
into food is affected by:
A.
Brand of equipment
B.
Dielectric properties and moisture content
C.
Packaging color only
D.
Only the color
Question No. 42
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What is the primary application of
electron beam irradiation
?
A.
Heating food
B.
Deep penetration in thick products
C.
Freezing
D.
Surface and near-surface treatment
Question No. 43
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In
PEF technology
, which factor is critical for microbial inactivation?
A.
Electric field strength (kV/cm)
B.
Color of electrodes
C.
Atmospheric pressure
D.
Packaging design
Question No. 44
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Which thermal technology is most similar to
ohmic heating
in heating mechanism?
A.
Steam heating
B.
Infrared heating
C.
Resistance heating
D.
Conventional oven
Question No. 45
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The Z-value in thermal processing represents:
A.
Sterilization time
B.
Temperature increase needed to reduce D-value by 90%
C.
Final product temperature
D.
Pressure level
Question No. 46
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What is a limitation of
pulsed light
technology?
A.
It requires days of treatment
B.
Limited penetration and shadowing effects
C.
It makes food radioactive
D.
It requires extreme cold
Question No. 47
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In
aseptic processing
, the combination of thermal and non-thermal methods involves:
A.
Only freezing
B.
Adding salt
C.
Only cold storage
D.
UHT sterilization followed by sterile filling
Question No. 48
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Which mechanism is
NOT
involved in ultrasound food processing?
A.
Cavitation
B.
Local heating
C.
Mechanical disruption
D.
Nuclear fission
Question No. 49
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The term
"commercial sterility"
in canned foods means:
A.
Only yeast is killed
B.
Absence of pathogenic and spoilage organisms under normal storage
C.
Presence of many bacteria
D.
Complete absence of all microorganisms
Question No. 50
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Which property of food is most important for effective
HPP treatment
?
A.
Shape
B.
High water activity
C.
Color
D.
Brand name
Question No. 51
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What is the primary advantage of using
radio frequency heating
for large food products?
A.
It adds flavor
B.
It works without electricity
C.
Better penetration depth than microwave
D.
Surface heating only
Question No. 52
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In
UV-C treatment
of water or clear juices, the optimal wavelength is approximately:
A.
800 nm
B.
400 nm
C.
600 nm
D.
254 nm
Question No. 53
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What is the main difference between
HPP and thermal processing
?
A.
HPP affects covalent bonds, thermal affects non-covalent bonds
B.
They are identical
C.
HPP uses high temperature
D.
HPP affects non-covalent bonds, preserving nutrients better
Question No. 54
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Which factor limits the use of
PEF
technology for solid foods?
A.
It makes food toxic
B.
Temperature requirement
C.
It is too slow
D.
Need for liquid or pumpable products
Question No. 55
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In
infrared pasteurization
, which factor most affects heating rate?
A.
Color of container
B.
Time of day
C.
Surface absorption properties of food
D.
Room humidity
Question No. 56
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What is the purpose of combining
ohmic heating with PEF
(hurdle approach)?
A.
To slow down processing
B.
To increase cost only
C.
To add preservatives
D.
Synergistic microbial inactivation with minimal quality loss
Question No. 57
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Which statement about
cold plasma
is correct?
A.
It makes food radioactive
B.
It only works in vacuum
C.
It is the fourth state of matter
D.
It requires temperatures above 200°C
Question No. 58
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The
F-value
in thermal processing represents:
A.
Fat content
B.
Freezing point
C.
Equivalent sterilization time at reference temperature
D.
Final temperature
Question No. 59
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What is a major challenge in scaling up
non-thermal technologies
for industrial use?
A.
They require no electricity
B.
They work too quickly
C.
They are too simple
D.
Equipment cost and throughput limitations
Question No. 60
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In
microwave-assisted thermal sterilization (MATS)
, the advantage over conventional retort is:
A.
Faster heating and better quality retention
B.
Only surface heating
C.
No electricity needed
D.
Lower equipment cost
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