Food preservation, Principles and its methods
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Question No. 1
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Food preservation is primarily concerned with
controlling
which of the following factors that cause food spoilage?
A.
Microbial growth, enzymatic activity, and chemical reactions
B.
Storage duration only
C.
Temperature and humidity only
D.
Packaging materials only
Question No. 2
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The principle of
asepsis
in food preservation involves:
A.
Removing oxygen from food packaging
B.
Keeping microorganisms away from food by using barriers
C.
Adding chemical preservatives to food
D.
Killing all microorganisms present in food
Question No. 3
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Which temperature range is typically used in
HTST pasteurization
for milk?
A.
100°C for 10 minutes
B.
135-150°C for 3-5 seconds
C.
72°C for 15 seconds
D.
63°C for 30 minutes
Question No. 4
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The water activity (aw) level below which most
pathogenic bacteria
cannot grow is:
A.
0.75
B.
0.65
C.
0.95
D.
0.85
Question No. 5
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Blanching is primarily used to:
A.
Inactivate enzymes before freezing or canning
B.
Remove moisture from vegetables
C.
Kill pathogenic microorganisms in food
D.
Add flavor to processed foods
Question No. 6
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Which of the following is the
most heat-resistant
form of microorganisms?
A.
Vegetative bacteria
B.
Bacterial spores
C.
Molds
D.
Yeasts
Question No. 7
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The pH level below which most
spoilage bacteria
are inhibited is:
A.
4.6
B.
5.0
C.
3.5
D.
6.0
Question No. 8
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High Pressure Processing (HPP) typically uses pressure levels of:
A.
400-600 MPa
B.
1200-1500 MPa
C.
100-200 MPa
D.
800-1000 MPa
Question No. 9
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The antimicrobial effect of
salt (NaCl)
in food preservation is primarily due to:
A.
Increasing temperature during processing
B.
Lowering the pH of food
C.
Producing toxic compounds
D.
Creating osmotic pressure and reducing water activity
Question No. 10
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Which preservative is commonly produced by
Lactococcus lactis
and used in dairy products?
A.
Nisin
B.
Benzoic acid
C.
Sorbic acid
D.
Propionic acid
Question No. 11
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The D-value in thermal processing represents:
A.
The maximum safe storage temperature
B.
The minimum processing time for sterilization
C.
Time required to reduce microbial population by 90% at a specific temperature
D.
The temperature needed to kill all microorganisms
Question No. 12
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Freeze-drying (lyophilization) preservation works by:
A.
Adding chemical preservatives during freezing
B.
Converting ice directly to vapor under vacuum
C.
Heating food while frozen
D.
Rapid freezing followed by slow thawing
Question No. 13
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The
hurdle technology
concept in food preservation involves:
A.
Combining multiple mild preservation methods
B.
Using only natural preservation methods
C.
Using only one preservation method at high intensity
D.
Building physical barriers around food
Question No. 14
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UHT (Ultra High Temperature) processing typically involves heating to:
A.
121°C for 15 minutes
B.
72°C for 15 seconds
C.
135-150°C for 2-5 seconds
D.
85°C for 30 minutes
Question No. 15
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Which of the following is a
Class I traditional preservative
?
A.
Sodium benzoate
B.
Potassium sorbate
C.
Vinegar (acetic acid)
D.
Sulfur dioxide
Question No. 16
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The antimicrobial mechanism of
organic acids
primarily involves:
A.
Disrupting cell wall synthesis
B.
Depleting cellular ATP by forcing cells to pump out protons
C.
Coagulating cellular proteins
D.
Binding to DNA
Question No. 17
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Modified Atmosphere Packaging (MAP) typically involves:
A.
Removing all gases from packaging
B.
Using only vacuum packaging
C.
Replacing air with nitrogen or carbon dioxide mixtures
D.
Adding oxygen to prevent anaerobic spoilage
Question No. 18
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The critical pH level that distinguishes
high-acid
from
low-acid
foods for canning purposes is:
A.
3.7
B.
4.6
C.
5.5
D.
6.0
Question No. 19
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Pulsed Electric Field (PEF) preservation works by:
A.
Creating electromagnetic fields that disrupt cell membranes
B.
Adding antimicrobial compounds
C.
Removing oxygen from food
D.
Generating heat to kill microorganisms
Question No. 20
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The water activity (aw) of
fresh meat
is approximately:
A.
1.00
B.
0.95-0.99
C.
0.85
D.
0.75
Question No. 21
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Cold plasma food preservation primarily works by:
A.
Freezing food to very low temperatures
B.
Removing heat from food packaging
C.
Creating ice crystals in food
D.
Generating ionized gas molecules that kill surface microorganisms
Question No. 22
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The main advantage of
irradiation
over thermal processing is:
A.
Lower cost of processing
B.
Better flavor retention
C.
Faster processing time
D.
Processing can occur at ambient temperature
Question No. 23
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Fermented foods are preserved primarily through production of:
A.
Alcohol and carbon dioxide
B.
Hydrogen peroxide
C.
Enzymes and proteins
D.
Lactic acid and other organic acids
Question No. 24
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The principle behind
osmotic dehydration
is:
A.
Applying vacuum to extract water
B.
Using concentrated salt or sugar solutions to draw out moisture
C.
Removing water using high temperatures
D.
Freezing water to separate it from food
Question No. 25
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Edible films and coatings preserve food by:
A.
Changing the pH of food surface
B.
Adding antimicrobial compounds directly to food
C.
Creating barriers to moisture, oxygen, and microorganisms
D.
Increasing the temperature of food
Question No. 26
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The safe storage temperature for
refrigerated foods
to slow bacterial growth is:
A.
4°C or below
B.
-5°C or below
C.
10°C or below
D.
0°C or below
Question No. 27
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Smoking preserves food through:
A.
Creating vacuum conditions
B.
Adding salt only
C.
Dehydration and antimicrobial compounds from smoke
D.
High temperature cooking only
Question No. 28
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The term
'commercial sterility'
means:
A.
Destruction of pathogenic and spoilage microorganisms under normal storage
B.
Removal of all bacteria but not viruses
C.
50% reduction in microbial load
D.
Complete destruction of all microorganisms
Question No. 29
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Vacuum packaging preserves food primarily by:
A.
Removing oxygen to prevent aerobic spoilage
B.
Heating the food during packaging
C.
Increasing internal pressure
D.
Adding inert gases
Question No. 30
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The
Z-value
in thermal processing indicates:
A.
Minimum time for sterilization
B.
Time to kill 90% of microorganisms
C.
Temperature change needed to change D-value by factor of 10
D.
Maximum safe processing temperature
Question No. 31
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Natural antimicrobials from plants typically include:
A.
Artificial flavoring agents
B.
Inorganic salts only
C.
Synthetic chemicals only
D.
Phenolic compounds, terpenes, and essential oils
Question No. 32
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The main disadvantage of
high-temperature processing
is:
A.
High water activity in final product
B.
Ineffective against microorganisms
C.
Increased microbial growth after processing
D.
Loss of heat-sensitive nutrients and sensory quality
Question No. 33
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Biopreservation involves using:
A.
Artificial additives only
B.
Chemical preservatives only
C.
Natural or controlled microorganisms and their metabolites
D.
High temperatures only
Question No. 34
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The principle of
canning
preservation combines:
A.
Heating and hermetic sealing
B.
Drying and smoking
C.
Fermentation and salting
D.
Freezing and vacuum packaging
Question No. 35
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Nanoencapsulation in food preservation helps by:
A.
Increasing food size
B.
Reducing food nutrition
C.
Changing food color only
D.
Providing controlled release and protection of antimicrobials
Question No. 36
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The water activity level that prevents
mold growth
is typically:
A.
Below 0.75
B.
Below 0.65
C.
Below 0.95
D.
Below 0.85
Question No. 37
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Ultrasound-assisted preservation works through:
A.
Removing all moisture from food
B.
Heating food to high temperatures
C.
Adding chemical preservatives
D.
Cavitation effects that disrupt microbial cells
Question No. 38
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The main advantage of
freeze-drying
over conventional drying is:
A.
Lower equipment cost
B.
Better retention of structure, nutrients, and flavor
C.
Higher final moisture content
D.
Faster processing time
Question No. 39
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pH levels most favorable for
yeast growth
in foods are:
A.
3.0-4.5
B.
4.0-6.5
C.
7.0-9.0
D.
1.0-2.0
Question No. 40
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Parabens (p-hydroxybenzoic acid esters) are effective against:
A.
Yeasts and molds primarily
B.
Enzymes only
C.
Viruses only
D.
Bacteria only
Question No. 41
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The concept of
HACCP
in food preservation emphasizes:
A.
Using only chemical preservatives
B.
Applying maximum heat treatment
C.
Identifying and controlling critical control points
D.
Using traditional methods only
Question No. 42
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Sulfur dioxide (SO2) is most effective in preserving:
A.
High-fat foods
B.
Acidic foods and beverages
C.
High-protein foods
D.
Neutral pH foods
Question No. 43
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The term
'shelf-stable'
refers to foods that:
A.
Must be refrigerated always
B.
Can be stored at room temperature without spoilage
C.
Need freezing for preservation
D.
Spoil within 24 hours
Question No. 44
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Active packaging differs from conventional packaging by:
A.
Being biodegradable only
B.
Having larger size
C.
Interacting with food or environment to enhance preservation
D.
Being more colorful
Question No. 45
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The
F-value
in thermal processing represents:
A.
Time equivalent at reference temperature for sterilization
B.
Frequency of heating cycles
C.
Fahrenheit temperature used
D.
Final product temperature
Question No. 46
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Controlled atmosphere storage differs from modified atmosphere packaging by:
A.
Using different gas compositions
B.
Maintaining and monitoring gas levels continuously
C.
Using different packaging materials
D.
Operating at different temperatures
Question No. 47
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The most important factor determining
thermal resistance
of microorganisms is:
A.
Type and physiological state of microorganism
B.
Size of the organism
C.
Processing equipment used
D.
Water content of food
Question No. 48
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Natural fermentation preservation relies on:
A.
Indigenous microflora producing acids and antimicrobials
B.
Chemical additives only
C.
Addition of external starter cultures only
D.
High temperature processing
Question No. 49
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The critical factor in
retort processing
for low-acid canned foods is:
A.
Achieving F0 value sufficient to destroy C. botulinum spores
B.
Maintaining product color
C.
Preventing can corrosion
D.
Minimizing processing time only
Question No. 50
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The main limitation of
pulsed light
preservation is:
A.
Limited penetration depth into food
B.
High energy consumption
C.
Ineffectiveness against microorganisms
D.
Production of toxic compounds
Question No. 51
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Bacteriophages in food preservation work by:
A.
Reducing pH of food
B.
Increasing osmotic pressure
C.
Specifically infecting and lysing target pathogenic bacteria
D.
Producing antimicrobial chemicals
Question No. 52
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The advantage of
supercritical CO2 extraction
in food processing is:
A.
Low equipment cost
B.
High temperature operation
C.
Fast processing time
D.
Leaving no chemical residues and preserving heat-sensitive compounds
Question No. 53
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In
high-acid foods
, the primary concern for preservation is:
A.
Yeast and mold control
B.
Enzyme activation
C.
Bacterial spore destruction
D.
Virus inactivation
Question No. 54
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The mechanism of
ohmic heating
involves:
A.
Electrical resistance heating within the food
B.
Steam injection
C.
Infrared radiation
D.
Microwave radiation
Question No. 55
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Smart packaging in food preservation can:
A.
Only change color
B.
Monitor and indicate food quality changes
C.
Only provide barrier properties
D.
Only reduce packaging weight
Question No. 56
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The main challenge with
essential oils
as natural preservatives is:
A.
Low antimicrobial activity
B.
Regulatory restrictions only
C.
Strong flavor impact and potential sensory changes
D.
High cost only
Question No. 57
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Pulsed Electric Field (PEF) processing is most suitable for:
A.
Dry foods only
B.
Solid foods only
C.
Liquid and semi-liquid foods
D.
Frozen foods only
Question No. 58
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The primary difference between
pasteurization and sterilization
is:
A.
Temperature used only
B.
Time duration only
C.
Complete vs. partial destruction of microorganisms
D.
Equipment used only
Question No. 59
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Enzymatic browning in foods can be prevented by:
A.
Increasing light exposure
B.
Increasing temperature only
C.
Adding more water
D.
Blanching, acidification, or removing oxygen
Question No. 60
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The future trend in food preservation is moving toward:
A.
Only traditional methods
B.
Higher temperature processing
C.
Higher chemical preservative use
D.
Combination of mild non-thermal methods with natural antimicrobials
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